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02/2000 PASTING GHS32 PLOTS INTO YOUR OWN DOCUMENTS

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1. 0 FLOOR WEIGHT COND 1 FSM DAMCALC Damaged Tanks FSM COND 2 FSM DAMCALC Damaged Tanks FSM US Code of Federal Regulations 47 170 290 by c 2 Damage stability using moments of transference WEIGHT COND 1 DAMCALC Damaged Tanks COND 2 DAMCALC Damaged Tanks ae me e m n n m n e e n m e m mel 0 Introduction to Macros 4 95 Applies to GHS amp BHS Macros are found in various kinds computer programs The mainline application programs such as word processors spread sheets and data base programs often provide something called a macro facility Macro literally means large and in computer jargon it generally refers to a command which may be made up of a large number of other commands Most of the macro facilities found in application programs are built in versions of what was a common utility a few years ago the keyboard macro program They function basically by recording keystrokes allowing you to collect the keystrokes as a named macro and play them back at a later time by invoking the macro name However such macro facilities are awkward and of limited use compared to an older tradition in which the macro is an extension of a programming language Most assembly languages have macros of this type as do a few higher level languages Even DOS which is itself a rudimentary language has a macro facility known as the batch file It is this type of lan
2. Using the Salvage Extensions With GHS the Q Menu system has a variation which is more useful for salvage work To enable the salvage menu 1 Edit the file QVERSION LIB Place a comment mark before the line which runs QMAIN G and remove the comment mark before the line which runs QMAIN S LIB Modifications Modifications and extensions can be made to the Q Menu system without changing the files as distributed This ensures that future updates from the vendor will not overwrite the files you have changed You can put your extensions and modifications in new files and attach them by adding lines to the QVERSION LIB file similar to the one which calls QUSER LIB See QUSER LIB for examples of how to add stability criteria and extend the menu system ae m a i en a i i a i i i i la GHS LIMIT commands based on Navy stability criteria 8 97 Intact severe wind and wave HMMT WIND C2 ROLL 25 LIM RISE gt 0 667 LIM RESIDUAL RATIO FROM ROLL TO RAO gt 1 4 Lifting Crowding amp Turning HMMT x CS LIM RISE gt 0 667 LIM ABS ANGLE AT EQU lt 15 LIM ABS RATIO FROM EQU TO RAO gt 1 667 Towline adds to Lifting LIM ANGLE FROM MAX TO ABS 40 OR FLD gt 0 LIM ABS RATIO FROM EQU TO ABS 40 OR FLD gt 1 667 Damage LIM ABS ANGLE AT EQU lt 15 LIM RESIDUAL RATIO FROM ROLL TO ABS 45 OR RAO gt 1 4 LIM RESIDUAL RATIO FROM ROLL TO FLD OR RAO gt 1 4 roll angle depends on displacement These interpretations of the Na
3. cd 1 2 roll IMO k 0 7 Input appropriate k hmmt wind const hmmt report solve he roll ra 0 5 60 lim Maxvcg curves can be run using the same run files The SOLVE HE ROLL and RA commands should be replaced by the MAXVCG command The MAXVCG command will solve for equilibrium and apply the roll correctly in its iterative search for the maximum VCG Users should review and understand the Severe Wind and Rolling criteria and the applicable GHS commands before using GHS to perform the calculations The HMMT REPORT and ROLL commands can be used to see how GHS is calculating the heeling moment and the roll angle New Stability Standards for Small Fishing Vessels Effective September 15 1991 final regulation by the U S Coast Guard governing fishing vessels substantially tighten stability requirements The regulation is to implement provisions of the Commercial Fishing Industry Vessel Safety Act of 1988 and applies to vessels built after the effective date It also affects those vessels that undergo major conversion and operate with 16 or more persons Thirteen public hearings were held in all coastal regions of the United States Concerns of the fishing industry centered upon the proposed adoption of IMO s stability standards A group of Seattle Naval Architects submitted calculations and examples at the public hearing in Seattle to demonstrate that the proposed rules were far too severe and failed to take into account the
4. it uses the waterplane only unless the heel axis has been rotated When the RA process derives GM from the waterplane it automatically projects the CG into line with the CB in a direction parallel to the waterplane Therefore it produces the correct GM when a heeling moment is involved insofar as the waterplane is concerned When the RA process derives GM from the righting arm curve it samples small angles of heel on either side of the relevant angle in order to determine the slope of the curve The RA command will tend to use the righting arm slope method if the parameter GMRA is included However it will also look at the GM from the waterplane and use a blend of the two unless there is a large difference in which case it uses the slope of the righting arm curve This gives a smoother response in the presence of waterplane discontinuities while keeping as much agreement with the waterplane method as possible Waterplane discontinuities cause knuckles in the righting arm curve at which its slope and the GM are discontinuous By using the sampling method to determine the slope of the righting arm curve the GM discontinuity is smoothed which helps when optimizing for a particular GM value which may not in fact exist Therefore the GMRA parameter can be used with the MAXVCG SOLVE VCG and SOLVE WEIGHT commands to improve their performance when GM limits are in a controlling position When the heel axis has been rotated the righting arm slope is
5. the parameters in brackets being optional and mutually exclusive With neither optional parameter the heeling moment calculation is deferred until a time when a heeling moment is actually needed at which time it is calculated from the lateral projection at the then present depth heel and trim The presence of either the C2 or the CONST parameter causes a heeling moment to be calculated at zero heel and trim using the current weight to obtain the depth Once the HMMT command has been issued establishing a heeling moment function there are three things which may done 1 The SOLVE command may be issued to find the heel angle where heeling and righting moments are equal ie the equilibrium heel angle in the presence of the wind 2 The RA command may be issued to compute a residual righting arm curve 3 The MAXVCG command may be used to find maximum VCG values relative to a Suitable stability criterion Not available in BHS or BHS YACHT ae een en a n n n m a e e n ee n e 0 USCG Severe Wind and Rolling Criterion for Fishing Vessels 4 95 The calculation of the Severe Wind and Rolling Criterion required by the new USCG Commercial Fishing Vessel Safety Regulations is different from the IMO Severe Wind and Rolling criterion as given in NVIC 5 86 and therefore requires a slightly different approach in GHS The IMO Severe Wind and Rolling criterion subjects the vessel to a steady wind heeling arm The
6. u solve macro stat With water on deck wave height hs meters hw hw meters status macro ra heel 0 ra area nowarn Start of project commands Get geometry project testwod if fexist project gf then read else makeship report nograph Set ship weight and C G draft 4 5 vcg 5 solve weight lcg Set point of damage variable pod set pod 50a 10s 8 Point of damage also used to determine freeboard refpt hull pod Select deck to be flooded tank deck c refpt pod type flood Induce heeling moment tcg 0 5 Initial condition without water on deck solve status Set wave height variable hs set hs 2 75 Wave height in meters macro case page 2 method wod 1 Stat a case neu Northern European case poe Panel of Experts view Probabilistic Damage The IMO Subdivision Index for Cargo Ships 1 95 Probabilistic damage refers to a method for computing a measure of probable damage survivability which takes into account not only the vessel s stability when certain subdivisions of the ship are damaged but assigns probabilities to various extents of damage as well as to the survivability when so damaged The products of these probabilities are summed over the various possible combinations of flooding which could occur from a single breach of the hull and the result is called the Attained Subdivision Index I
7. used to check compliance with a stability requirement or passed on as a parameter in other GHS commands In addition to user variables GHS utilizes several system variables System variables make the current value for certain internal variables available to the user Such system variables include the fixed weight and center total weight and center some tank information displaced volume and center of buoyancy project name and origin description to name a few A complete listing of system variables is in the user manual under the variables command These variables can be accessed and implemented the same way as user variables The only difference is that system variables do not need to be declared and their values are automatically updated by GHS The first step to using user variables is to declare each variable Users familiar with basic programming practices will recognize the elements involved in a GHS declaration A declaration is made with the variable command When issued with parameters the variable command defines the type of variable s being declared Two types are acceptable real or string If a variable type is not specified the default is real Optionally the minimum and maximum value to be allowed with each can be given For real variables the min max values given are real numbers for string variables the min max values given are the minimum and maximum number of characters the variable is allowed For example to declare a real
8. MODE command in it Thereafter you can set the communication parameters merely by typing the name of the batch file iii 0 Downflooding Points 4 95 Applies to GHS BHS amp BHS Yacht version 6 20 and later The CRTPT Command GHS maintains a list of Critical Points which are not associated with any particular part of the vessel model but are used as points of down flooding and other purposes relating to the vessel as a whole Critical points may be specified through Part Maker in the model building stage They may also be specified and changed with the main program A Critical Point consists of a name and a location longitudinal transverse and vertical coordinates It also has two additional attributes Symmetry status and Flooding status The Symmetry status of a Critical Point indicates whether the point is to be regarded as the single point represented by its coordinates asymmetrical or as actually two points one symmetrically opposite the other by negation of the transverse coordinate By default the Symmetry status is asymmetrical To make it symmetrical the following form of the CRTPT command is used in the Main Program not Part Maker CRTPT SYMMETRICAL Any use of a critical point which implies only one point eg the HEIGHT command uses only the point as given and ignores the Symmetry status The Flooding status has three states Flooding Tight and Noflooding Flooding means that th
9. RA SOLVE other Neither FSM nor TRUEFSM used USERFSM Discontinued VCG MAX See GHS Applications US Code of Federal Regulations 46 170 285 Intact stability using maximum FSMs Allows tank LCG shifts to contribute to initial trim Forces initial heel to zero by adjusting TCG Raises C G normal to waterplane Uses maximum FSM values derived at zero heel and zero trim for all tanks Always counts at least Big Consumables FSM Only counts other consumables FSMs if they exceed Big Consumables for each consumable type Note This is not the only interpretation of this regulation MACRO FLOOR FSMFLOOR OFF FSMMT MAX STATUS TANKS FSM Determine by inspection the Big Consumables from above FSM values FSMMT 0 LOAD 0 FSMMT Big Consumables MAX FSMFLOOR FSM STATUS TANKS FSM Documents the derivation of the floor FSM MACRO COND DELETE ALL WEIGHTS LOAD 0 LOAD 1 MACRO CALC HEEL 0 TRIM 0 SOLVE TRIM TCG STATUS FSM Documents the current condition amp FSM GHS RA FSM HEEL 0 TRIM 0 FLOOR FSM MAX WEIGHT COND 1 CALC COND 2 CALC For a more realistic calculation in the spirit of 170 285 substitute FSMEXTRA for FSM on the RA command US Code of Federal Regulations 46 170 290 by c 1 Damage stability using FSM at 5 degrees heel MACRO DAMCALC TANKS 1 TYPE FLOODED HEEL 0 SOLVE STATUS 2 ANGLES RA 2 TYPE INTACT MACRO FSM HEEL 5 TRIM 0 FSMMT PRESENT HEEL 5 TRIM
10. being compared with the maximum VCG GHS Facilities for using FSM In order to accommodate these applications GHS associates two FSM functions with each tank One function is used for load factors between zero and just under 95 The other is used with loads from 95 to 100 Each FSM function is allowed to have one of three forms 1 a constant value 2 a constant value except at zero and 100 loads where the value becomes zero and 3 a variable equal to the true FSM value at each particular load GHS allows the value used by the first two forms of the FSM function to be either specified directly by the user or taken from the FSM present in a particular load at a particular heel and trim A means of finding the load which has the maximum FSM at a particular heel and trim is available In addition GHS provides for a minimum FSM a floor value which becomes the effective FSM when it is greater than the FSM sum from the tanks In addition to the overall FSM floor individual FSM floors can be designated for each of the various descriptions of tank contents Assigning FSM functions to a tank is done by means of the command which has the form FSMMT tanklist f1 f2 VUNCONDITIONAL tanklist is a list of the names of the tanks to be affected f1 is the function which applies when 0 0 6 load lt 0 95 f2 is the function which applies when 0 95 6 load 6 1 00 If f2 is not specified it becomes identical to f1 The variable or true FSM form
11. gt LS then err Blocks go beyond end of slipway end Find number of steps to take set N LS MINUS L DIV DL PLUS NB macro step solve subtitle page status weight displ wpl total Is notab set LS LS MINUS DL set D depth PLUS DI depth D if LS gt L then exit if NB lt 1 then exit delete Block NB set NB NB MINUS 1 set L L MINUS DL Step N end
12. is one 5 of the length of the hull could have as few as two stations Depending on the shape of the tank its level of loading and the attitude of the surface the error involved could be quite substantial in terms of the tank itself though it would not necessarily be significant in terms of the overall ship With only two stations where their areas are very dissimilar the volume error could be as high as 20 Therefore a good practice is to ensure that major components in all parts have at least four stations reducing the error liability due to station spacing to about 5 If accurate tank properties are required independent of the tank s size relative to the size of the ship then the overall length of the tank itself should be used as the guide in selecting the station spacing The usual process of creating a tank component within a hull involves the FIT HULL process which provides the resulting component with stations at the locations of intervening hull stations in addition to its own end stations If more stations are required the SPACING statement can be included within the CREATE command User Variables and Variable Arithmetic 7 98 User variables have been available in the GHS command language for some time Typically used in macros and run files user variables allow certain operations to be performed in the GHS environment With user variables values not normally used or directly computed by GHS can be determined reported
13. maxvcg data base then the command MAXVCG without parameters will access the data base and report the maximum VCG which corresponds to the present condition The maximum VCG curves and the data base which result from a MAXVCG command are based on certain factors which must be identically present whenever the curves are applied These factors include the stability criterion the heeling moment and the configuration of damage When any of these factors are changed the data base becomes invalid and can no longer be accessed It is possible to produce a composite data base consisting of the lowest maximum VCG values from more than one execution of the MAXVCG command Details can be found in the MAXVCG command section of the Command Dictionary or by typing HELP MAXVCG at the GHS prompt When damage is present tanks with type FLOODED the MAXVCG command keeps the tanks in the flooded state but it still assumes that the TCG is zero This means that the resulting maximum VCG data does not apply to load conditions where the flooded tanks carry any load before damage since the loss of the load would change the condition When the assumptions inherent in the maximum VCG curves cannot be satisfied it is necessary to analyze each case of loading separately This can be done by beans of the SOLVE MAXVCG command After setting a load condition weights and tank loads the SOLVE MAXVCG command will find the maximum value of the lightship VCG or the VCG of a particu
14. must be added set fsa fsmmt div displ and then the calculation for gmact would be set gmact bmt plus vcb sub vcg sub fsa The pressure commands sets the wind pressure to be used according to 46CFR 170 170 a Be sure consistent units are used Next the heeling moment due to wind is computed and reported for the current condition The const parameter causes the heeling moment calculated to be that at zero heel The following set command takes the present value of the system variable hmmt the current heeling moment and assigns it to the user variable windmom Finally a righting arm calculation is executed so the system variable limmarg is set to the appropriate angle and the required GMt can be computed according to 46 CFR 170 170 a Once the required GMt and actual GMt are known these values can be compared with an if statement and the string variable wxsat set to report the results Note that in the if command the user variables in the condition statement are contained in brackets Since these expressions are not always variable names GHS needs to be signaled that variables are being used Once the above macros are incorporated into a run file a line must be added to the run file to execute these macros for example 170170 170calcs Getting GHS to evaluate the US Coast Guard Weather Criterion is just one possible use of user variables and variable arithmetic By making use of the features in the note command and the o
15. printer unless you establish a persistent connection using NET EXE To do so use the following syntax at a command prompt NET USE LPTn server printer PERSISTENT YES When printing to a Novell Netware 3 12 queue Microsoft suggests using the following syntax instead NET USE LPTn server queue If the port is redirected successfully the following message should appear The command completed successfully To disconnect persistent LPTn connections use the following syntax NET USE LPTn DELETE ALTERNATE PROCEDURE FOR NOVELL NETWARE Some Novell Netware users report that the above Microsoft commands do not work for them and suggest replacing them with the following Netware commands To connect a networkprinter to LPTn use the following syntax CAPTURE L n Q networkprinter NB NFF NT TI 30 To disconnect type ENDCAP Misleading Bewildering and Unreliable Stability Criteria 11 97 Difficulties with Equilibrium Angle as a Measure of Stability The ability to resist a heeling moment resulting from wind passenger crowding etc is often measured by the heel angle which is induced by the heeling moment However requiring that this angle of equilibrium be less than some given angle such as 14 degrees or some characteristic angle such as margin line immersion downflooding point immersion or half freeboard does not in itself guarantee finite stability with the heeling moment It says nothing about what happens if the heel is increa
16. projected lateral area H the vertical distance from the center of the projected lateral area to the center of the underwater lateral area W displacement 14 degrees or the angle at which one half the freeboard to deck edge is immersed whichever is less The angle at which the heeling arm curve and righting arm curve intersect is the angle of equilibrium Therefore at equilibrium PAH GM sin cos 3 W PAH GM 4 W tan The Weather Criterion requires that 4 must be satisfied for each condition of loading and operation Three LIMIT commands are required by GHS in order to apply this criterion The first LIMIT command assures that the angle of equilibrium occurs before 14 degrees or the angle at which one half the freeboard to deck edge is immersed whichever is less It is defined as LIMIT 1 ANGLE from EQU to ABS 14 or HF gt 0 The HF keyword short for Half Freeboard refers to the angle at which one half the freeboard to deck edge is immersed In this case the angle from equilibrium to the lesser of 14 or HF must be greater than zero Before you can use the HF keyword you must first mark the deck edge of the vessel The deck edge is marked in Part Maker using the MARGIN command For this criterion the amount of the margin does not matter You could use zero or any other value For example modify hull hull c margin 0 When you view the vessel using the DISPLAY command you should
17. report ra 0 5 60 lim USCG Calculation The major difference between the two criteria is where the angle of equilibrium is taken i e steady wind intercept vs gust wind intercept The GUST 1 5 parameter can not be used with the HMMT WIND command to calculate the required gust wind angle of equilibrium when evaluating the USCG criterion The GUST 1 5 parameter will not calculate the gust wind heeling arm until after the HE ROLL command is excecuted Therefore the angle of equilibrium will be taken at the steady wind intercept and the roll will be taken from the wrong angle of equilibrium To evaluate the USCG criterion correctly the user must input a wind speed which produces the correct gust wind heeling arm Specifying a wind speed of 65 4 knots produces the same heeling moment as does setting a steady wind speed equal to 53 4 knots and using the GUST 1 5 parameter A user defined gust wind speed allows for the correct angle of equilibrium i e gust wind intercept to be evaluated The roll will then be taken from the gust wind angle of equilibrium to windward before the residual areas are compared Both limits can be set and evaluated in one step The following is an excerpt from a run file that may be used after the vessel is loaded to evaluate the USCG criterion correctly lim 1 abs angle at equilibrium lt 14 lim 2 res ratio from roll to abs 50 or ra0 gt 1 lim 3 res ratio from roll to fld or ra0 gt 1 wind 65 4
18. see a line marking the deck edge GHS does not make the assumption that the righting arm curve is a sine curve actual righting arms are calculated for each angle of heel If only the angle of equilibrium is considered it is possible to have a righting arm curve which satisfies LIMIT 1 above but has very little righting energy up to the angle or in extreme cases a negative GM at zero heel In order to insure that the true righting arm curve provides as much energy as would a sine curve a second LIMIT command is required It is derived from 1 and 2 as follows 12 0 Area RA 6 RAdi 0 i2 6GMsinidi oo 3 2 GM cos 50 GM 1 cos i2 Heeling arm GM tan 2 cos i2 6 Area HA 6 HA di 0 i2 GM tan i2 cos 0 0 352 GM tan i2 sin 30 GM tan 2 sin i2 sin 2 i2 Il Q Area RA GM 1 cosi2 Area HA sin 2i2 cos 12 1 cosi2 sin 2 i2 0 492 i2 14 degrees The following LIMIT command can therefore be used to force the righting arm curve to be equal or better than the sine curve with regard to area energy LIMIT 2 ABS RATIO from ABS 0 to ABS 14 gt 0 492 An additional limit is required to guarantee that stability exists beyond the angle of equilibrium This could be a measure of the range of stability or the residual area For example if the range of stability is to be at least 15 beyond equilibrium the limit command would be LIMIT 3 ANGLE from E
19. variable called angle that will always be between 0 and 90 inclusive and a string variable name list that will always be PORT or STBD variable real angle 0 90 variable string list 4 4 Multiple variables of the same type can be declared on the same line If the variable command is issued without parameters a list of all the system and presently defined user variables appears with their current values A declared variable is undefined until a value is assigned to it This is done with the set or input command The set command will assign a value to the variable when the command is executed The input command typically executed in a run file will prompt the user to enter a value from the keyboard To demonstrate the use of variables the following commands can be used to have GHS check compliance with the US Coast Guard Weather Criterion 46 CFR 170 170 These commands can be executed as they appear below or be part of a run file that checks several intact stability criteria of the subject vessel As for any computation involving wind heel moments the lateral projected area must be part of the geometry and if the angle to half freeboard is suspected to be limiting the deck edge must be marked by defining a margin line in PartMaker clear read fvw gf draft 6 solve we lcg veg 12 variable real gmreq gmact variable read windmom tanang variable string wxsat 0 3 The above block of commands sets up the
20. 0 then exit variable ch ch2 HZ HZA r getangle DI Angle of deck immersion t heel t set ch cos heel set ch2 ch times ch tcg 0 solve trim tcg set HZ FTCG times ch set HZA HZ DIV ch2 tcg 0 status HZ HZ HZA HZA set r HZA div HZW HZA HZW r Should be greater than 1 0 protected 1 5 exposed macro hzb if skip lt gt 0 then exit variable HZB r fldpt on limit 1 area from abs 0 to abs 60 or fld gt 1 getarea getangle fld gethz t B Downflooding angle t Area area HZB HZB set r HZB div HZW HZB HZW r Should be greater than 1 1 protected 1 7 exposed macro hzc if skip lt gt 0 then exit variable HZC r fldpt off getangle ra0 limit 1 area from abs 0 to abs 90 gt 1 if t gt 90 then limit 1 area from abs 0 to ra0 or abs 120 gt 1 getarea gethz t C Angle of vanishing righting arm t if t lt 90 then NOTE This is not sufficient for exposed waters if t lt 70 then NOTE This is not sufficient even for protected waters Area farea HZC HZC set r HZC div HZW HZC HZW r Should be greater than 1 25 protected 1 9 exposed Set up condition draft 13 veg 12 5 solve weight lcg crtpt 1 downflooding point 50 10 30 macro case begin 1 hza hzb hzc case 1 4 lt put area to truncate here if max is lt 35 deg vc
21. 02 2000 12 1999 03 1999 07 1998 06 1998 05 1998 12 1997 11 1997 11 1996 08 1996 06 1997 06 1997 04 1997 04 1996 04 1996 03 1996 11 1995 06 1995 06 1995 05 1995 04 1995 04 1995 04 1995 04 1995 04 1995 04 1995 03 1995 01 1995 Ships PASTING GHS32 PLOTS INTO YOUR OWN DOCUMENTS GHS CONFIGURATION DIRECTORY CSI_SYS CFG Applying CFR 171 055 for Sailing Vessels User Variables and Variable Arithmetic Evaluating Vessels for Weather Criterion HOW TO PRINT TO A NETWORK PRINTER Getting your Printer to work with GHS Misleading Bewildering and Unreliable Stability Criteria Water on Deck GHS LIMIT commands based on Navy stability criteria Directory Management in GHS BHS and BHS Yacht The PROJECT Command The Q Menu System for GHS BHS and BHS Yacht The MAXVCG Process GM in GHS Accuracy considerations in selecting station spacing Evaluating Vessels for Weather Criterion 46 CFR 170 170 Wind and Rolling Calculations GHS BHS Demonstration Run File for End Launching Wind Heeling Moment Calculations Downflooding Points Using Free Surface Moments in Stability Calculations Introduction to Macros Building a Swath Tank Modes and Types USCG Severe Wind and Rolling Criterion for Fishing Vessels Interfacing a Digitizer with Section Editor Probabilistic Damage The IMO Subdivision Index for Cargo GHS CONFIGURATION DIRECTORY CSI_SYS CFG 12 99 GHS SE and related programs store hardware configuration information in a hidd
22. 2 If path begins with the only back slash it is taken to be the project sub directory name only The path to the master directory will be the same one established earlier or if none has been established the current directory will be assumed as the master directory Example PROJ 9705 Changes to subdirectory 9705 with in the previously established master directory 3 If path is only a back slash the previously established master directory and last used project subdirectory are assumed Example PROJ 4 If path is omitted altogether changes to the previously established master directory and lists the project subdirectories to choose from a en en en on eo e e een m el 0 The PROJECT Command 6 97 The PROJECT command has two purposes 1 It is used to define a project name of 1 to 8 characters This name appears on the upper right hand corner of the screen and printouts It is also used to form file names when they are omitted from certain commands For example PROJ ABC READ This defines the project name as ABC and reads the Geometry File ABC GF The project name is also carried in a system variable named PROJECT 2 It can be used to manage subdirectories for project files When used for this purpose the first parameter always contains at least one back slash except for one special case noted below It is assumed that there is a master project directory in which individual projec
23. DING DEPARTURE But what if you wanted to use two or more words If you threw some extra dummy parameters into the definition eg Condition 1 2 3 there would be no spaces between the words Condition 1 2 3 would give you an extra space or two if you happened to use less than three words The better solution is to enclose a multi word parameter in quotation marks For example HEADING Wing Tanks Damaged would take all three words strip off the quotation marks and then substitute them all for 1 Using the IF control command you can make a macro do different things depending on some variable or parameter For example you can check that the proper number of parameters is supplied at execution time MACRO LOAD IF 3 MESSAGE Parameter missing EXIT TANK 1 TYPE INTACT CONTENTS 3 LOAD 2 Another powerful feature of macros is their ability to create or spawn other macros This is often used when implementing menus in GHS For example MACRO WSET MACRO ESC EXIT MAIN Il MENU Weight setup 1 A ADD Add a weight item D DEL Delete a weight item spawns a little macro named ESC prior to executing the MENU command Notice that MACRO ESC is treated as ordinary text when WSET is defined with the exception that one of the slashes is removed from its terminating line Thus when WSET is executed it right away presents the system with a macro definition Incidentally when a GH
24. E and DAMAGED both involve determining the level inside the tank such that the pressure at the tank s Reference Point is the same inside the tank as it is outside the tank The tank s Reference point is set by the REFPT command and normally would be located on the tank s actual boundary though it can in fact be located anywhere Ps is the pressure at the surface of the liquid in the tank Pr is the pressure at the Reference Point Pc is the pressure contributed by the column of liquid in the tank from its surface to the Reference Point Pc ht C SGt Pr 1 d C SGs where ht is the height of the column d is the depth of the Reference below the external waterplane C is the pressure per unit depth of fresh water in atmospheres SGt is the specific gravity of the tank contents SGs is the specific gravity of the sea water In order to balance the pressures Pr Ps Pc In the Balanced Mode Vented Ps 1 atmosphere Therefore ht C BGL d C SGs ht d SGs SGt In the Balanced Mode Sealed Nominal Volume is defined such that Ps 1 atmosphere at Nominal Volume Load is defined as Load Actual Volume Maximum Volume Since for a gas pressure volume is constant Ps 1 Ln 1 La where Ln is the Nominal Load La is the Actual Load Therefore 1 d C SGs 1 Ln 1 La ht C SGt ht CO C1 C2 1 La where CO 1 C SGt C1 1 d C SGs C2 1 Ln This shows that ht is a function of La which i
25. HULL READ HULL GF Now we read the file containing the hull CREATE HULL STRUT Just to make things more tidy move the strut over SHAPE TEMP TEMP to the HULL part FIT HULL DELETE TEMP The TEMP part can now be deleted CREATE SWATH Let s call the part containing the final assembly CLASS HULL SWATH COMPONENT DECK Create the deck component ENDS 60 60 TOP 30 BOTTOM 25 OUTBOARD 28 COMPONENT S HULL Create the starboard hull component SHAPE HULL HULL VECTOR 0 20 0 This moves the CL component S HULL C over to the side COMPONENT P HULL Similarly for the port hull SHAPE HULL HULL VECTOR 0 20 0 COMPONENT S STRUT Same idea for the struts SHAPE HULL STRUT VECTOR 0 20 0 FIT DECK But make sure the struts don t overlap the deck COMPONENT P STRUT Similarly for the port strut SHAPE HULL STRUT VECTOR 0 20 0 FIT DECK DELETE HULL Now get rid of the original HULL part DISPLAY WRITE SWATH GF QUIT Tank Modes and Types 4 95 Applies to GHS amp BHS versions 6 20 and later GHS models the various ways in which tanks can behave by assigning to each tank a Type through the use of the TYPE command The LOAD and CONTENTS commands are used to set the volume of fluid within the tank and the density of the fluid respectively The most common and simplest tank type is INTACT An Intact tank contains a certain volume of liquid and the surface of the liquid is maintained such that it li
26. Q to RAO gt 15 To evaluate the stability of a vessel based on the Weather Criterion you must also set the heeling moment You can use the WIND and HMMT commands as follows WIND PRESSURE P HMMT WIND CS where P the wind pressure as calculated according to 46 CFR 170 170 a The values of A and H will be determined by GHS from the model and current waterplane All superstructure that is to be included in the lateral area calculations must be modeled If superstructure is to be included in the lateral area calculations but not in the buoyant volume of the vessel it must be modeled as a SAIL part These commands will then generate the heeling arm curve as defined in 2 Following is a simple run of commands which can be used to perform a weather criterion analysis READ filename REPORT WEIGHT w I t v LIMIT 1 ANGLE from EQ to ABS 14 or HF gt 0 LIMIT 2 ABS RATIO from ABS 0 to ABS 14 gt 0 492 LIMIT 3 ANGLE from EQ to RAO gt 15 WIND PRESSURE P HMMT WIND CS HEEL 0 RA 0 2 14 LIM Wind Heeling Moment Calculations 5 95 Applies to GHS BHS and BHS YACHT GHS offers several methods of modeling the effects of wind pressure ranging from a constant heeling moment directly supplied by the user to a variable heeling moment automatically computed from wind pressure on the lateral plane Regardless of the method chosen the HMMT command is the channel through which heeling moments are specified even when the heeli
27. R n and FSM on the same commands where USERFSM appeared Old method for applying maximum FSM values STATUS MAXFSM or STATUS MAXFSM tank list and MAXFSM on various other commands New method FSMMT MAX or FSMMT tank list MAX UNCONDITIONAL FSMFLOOR OFF and FSM on the same commands where MAXFSM appeared FSM and TRUEFSM Parameters In general the FSM parameter refers to the formal FSM value while the TRUEFSM parameter refers to the true FSM in the current condition The MAXFSM and USERFSM parameters are no longer used Following is a summary of the FSM parameters now available on various commands GHS FSM Use formal FSM values TRUEFSM Ignore formal values and use true values instead Default Same as FSM LOAD EDIT See GHS MAXVCG without primary parameters See GHS RA FSM Cause the tanks to be frozen and the C G to be raised perpendicular to the waterplane according to the formal FSM TRUEFSM Same as FSM except uses true FSM values FSMEXTRA Keeps tanks liquid but raises the C G according to the difference between the formal and true FSM Default Keep tanks liquid and do not change C G ROLL PERIOD Same as GHS except the default is TRUEFSM ROLL IMO See GHS STATUS FSM Use the formal FSM in the TANKS and WPL sections TRUEFSM Use the true FSM in the TANKS and WPL sections Default Do not show FSM in the TANKS section use the true FSM in the WPL section SOLVE MAX See
28. S process is aborted by your pressing the Escape key it looks for the presence of a macro named ESC and if it finds one it executes ESC instead of returning to the normal input stream When a macro is defined within a macro as in the example above you must be careful to avoid unintended parameter substitution in the inner macro Actually you cannot avoid parameter substitution because every n within the macro is replaced when the macro is used However you can use a little trick to get what you want anyway For example If the inner macro needs one parameter you would like it to retain a 1 after parameter substitution has taken place This can be done by putting 91 in place of the 1 assuming that the parent macro will always have less than 9 parameters The 9 is replaced by nothing leaving the 1 you wanted Although these brief examples were selected to demonstrate various features of GHS macros the primary overriding purpose in applying macros is to reduce repetition Whenever you find that you have to repeat a certain sequence of commands several times it is almost always better to construct a macro which contains the sequence and then execute the macro This reduces the repetition within the text of the Run File and thereby reduces the chance of making an input error While macros can be placed in any Run File and you will find that most Run Files are more compact and easier to check when they use macros it is sometimes convenient t
29. always used and the GM is actually in the direction of heel not the transverse direction In the presence of a heeling moment the GM which the RA process derives is always with respect to the absolute righting arm curve Therefore unless the heeling moment is constant at the angle at which GM is being considered the residual righting arm curve will have a slope which differs from the reported GM While the RA process can involve two cases of GM the RA plot can only show one GM line If both cases are present it shows GM upright In the absense of GM limits the RA plot shows GM only if the range of heel angles includes equilibrium e i i i m m c n n i i n mel 0 The MAXVCG Process 4 96 The purpose of the MAXVCG command is to produce curves of maximum VCG vs displacement based on a given stability criterion The assumption behind this is that all loadings which produce a given displacement and LCG have the same maximum VCG as well as having zero TCG Therefore when free surface is involved in a particular load the VCG must be adjusted for the free surface effect before comparing it with the maximum VCG The use of maximum VCG data should be restricted to loads where the TCG is zero The MAXVCG command takes a series of weights and LCGs as inputs and finds the corresponding maximum VCG for each combination of weight and LCG assuming that the TCG is zero Alternatively it accepts drafts and trims as inputs whi
30. board to deck edge is immersed In this case the angle from equilibrium to the lesser of 14 or HF must be greater than zero Before you can use the HF keyword you must first mark the deck edge of the vessel The deck edge is marked in Part Maker using the MARGIN command For this criterion the amount of the margin does not matter You could use zero or any other value For example modify hull hull c margin 0 When you view the vessel using the DISPLAY command you should see a line marking the deckedge GHS does not make the assumption that the righting arm curve is a sine curve actual righting arms are calculated for each angle of heel If only the angle of equilibrium is considered it is possible to have a righting arm curve which satisfies LIMIT 1 above but has very little righting energy up to the angle or in extreme cases a negative GM at zero heel In order to insure that the true righting arm curve provides as much energy as would a sine curve a second LIMIT command is required It is derived from 1 and 2 as follows The following LIMIT command can therefore be used to force the righting arm curve to be equal or better than the sine curve with regard to area energy LIMIT 2 ABS RATIO from ABS 0 to ABS 14 gt 0 492 An additional limit is required to guarantee that stability exists beyond the angle of equilibrium This could be a measure of the range of stability or the residual area For example if the
31. c AFT 43 FWD 29 7 WING 3 0 DIV 7 DIV 8 DIV 9 DIV 10 DIV MACRO case no2wbt s void1 s AFT 29 7 FWD 20 6 hold1 c no1wbt c no2wbt s void1 s AFT 20 6 FWD 9 4 thrstrm c 4 2 3 4 5 6 7 8 9 10 fpt c FWD 4 80 VCG 2 SOLVE WEIGHT LCG DAMSTAB SDIC case 6 5 7 13 case 4 684 6 564 QUIT Interfacing a Digitizer with Section Editor 3 95 The SE program interfaces with most digitizers through ADI drivers The driver is a small memory resident program which stands between the digitizer hardware and an application program such as SE The ADI standard was established by AutoDesk manufacturer of AutoCAD and is therefore very commonly used Most likely your digitizer came with an ADI driver file There are two forms of drivers Real Mode and Protected Mode SE uses the Real Mode form For example most mouse drivers are in Real Mode form Typically you install a Real Mode driver by executing an EXE file Some drivers are supplied as a SYS file which must be installed by including a DEVICE statement in the CONFIG SYS file which references the driver s SYS file When you install the driver you typically give a parameter indicating which serial port the digitizer is attached to You may also have to specify the baud rate etc but usually the driver will sense that automatically The exact details of the parameters you need to use when installing the driver should be provided by the documentation which
32. came with the digitizer If your digitizer is connected to serial port 1 you may find that the driver can be installed successfully without using any parameters If it is connected to another port the port number is commonly conveyed using only a slash followed by the port number For example port 2 would be drivername 2 Real Mode ADI drivers communicate with the application through a software interrupt vector which is identified by a particular interrupt number Since AutoCAD uses interrupt 121 79 hexidecimal this is the interrupt number which the driver will most likely assume by default Likewise SE assumes interrupt 121 SE and the ADI driver must both be using the same interrupt number in order to communicate SE supports two kinds of digitizers directly without the need of a driver These are the Summagraphics MM 1201 series and the Calcomp 9100 series When using SE with either of these digitizers and without a driver you must set the communication parameters of the serial port to agree with the settings used by the digitizer This is done by means of the MODE command in DOS For example MODE COM1 BAUD 9600 PARITY ODD DATA 8 STOP 1 sets the communication parameters of serial port 1 to 9600 baud etc Once set these parameters will remain in effect until changed by another program or until the computer is restarted Once you have established the parameters you will be using you can make a little batch file with the proper
33. ce the angle of the maximum For some range of VCG variations the experimental errors which are not proportional to the change of VCG will be more significant than the actual change in the curve do to the change of VCG This tends to bewilder the process of solving for the maximum VCG since the relationship between the VCG and the limit margin has become noisy and when taken at fine enough intervals is essentially random It is unfortunate that the angle of maximum righting arm has been included in some stability criteria While the computational difficulties are not unsurmountable the results often bear the effects of the experimental error This must be understood by those dealing with the results and appropriate allowances made GM at Equilibrium When the equilibrium angle is not upright increasing the VCG tends to increase the equilibrium angle If it so happens that this new heel angle encounters new buoyancy of sufficient magnitude to greatly boost the transverse moment of waterplane inertia the new GM may actually be higher than the original Therefore it is possible that the relationship between GM and VCG at equilibrium is the reverse of what would normally be expected Jumps in the Area to RAO If you have a double humped righting arm curve and your area or area ratio limit puts the valley between the humps right at the axis or just touching the heeling arm curve there will be a discontinuity in the area and probably in the a
34. ch it converts to weights and LCGs using the intact waterplane at zero heel When trim rather than LCG is an input the program must adjust the LCG in concert with the VCG in order to maintain the given initial trim This requires additional steps and takes additional time Since the details of any particular loading are irrelevant during the generation of maximum VCG curves the present weight and tank load settings are ignored during the process The present fixed weight VCG however is taken as the floor value If the MAXVCG process finds that a maximum VCG is below the floor it does not attempt to find its value but merely reports that it is less than the floor value In addition to displaying a table and graph of the maximum VCG curves the MAXVCG command causes a data base of the maximum VCG information is retained in memory This data base is also saved on a disk file by means of the SAVE command Although the data held in memory is lost when the GHS session ends it may be restored by RUNning the file which was written by the SAVE command This data base of maximum VCG data is accessible through two commands 1 a special short form of the MAXVCG command and 2 the LOAD EDIT command which is available only when the Load Editor module is included in the GHS installation When a particular condition has been defined weights and tank loads and equilibrium has been found nd the displacement LCG and TCG are within the limits required by the
35. commands to check the energy available to resist an IMO roll would be ROLL IMO WIND 53 4 HMMT WIND CONST SOLVE HEEL ROLL RA AREA _ If an increase in the heeling moment due to a gust of wind occurs at the rolled angle it can be modeled by using a GUST parameter on the HMMT command The issuance of the HEEL ROLL command then automatically causes the heeling moments to be multiplied by the gust factor from then on until another HMMT command is issued For example HMMT WIND CONST GUST 1 5 SOLVE HEEL ROLL lt The gust factor does not take effect until after this RA AREA When using the MAXVCG process the roll angle and gust factor are automatically applied in the proper sequence Thus ROLL IMO WIND 53 4 HMMT WIND CONST GUST 1 5 SOLVE MAXVCG is all that is necessary Further the MAXVCG command automatically recalculates the wind moments at each new draft when they are based on the lateral plane Hence ROLL IMO HMMT WIND CONST GUST 1 5 MAXVGG produces maximum VCG curves for a stability criterion involving the ROLL angle The LIMIT command used for establishing stability criteria accepts the keyword ROLL as an angle in which case it actually refers to the ROLL angle For example LIMIT RESIDUAL RATIO FROM ROLL TO ABS 50 OR FLD gt 1 expresses the IMO criterion for severe wind and rolling ho en enen an mon oo os enen en om e la GHS BHS Demonstration Run File for End Launching proj
36. e point will be regarded as a downflooding point as referenced by the FLD keyword in the LIMIT command and the DAMSTAB command Tight is similar to flooding but it applies only when the vessel is at the initial equilibrium angle At other heel angles the Tight critical points are considered to be nonflooding Noflooding means that the critical point is ignored as a flooding point The Flooding status can be set in the main program by appending one of the parameters FLOOD TIGHT or NOFLOOD to the CRTPT command The default is Flooding The FLDPT Command The FLDPT command works in conjunction with the CRTPT command It allows the Flooding status of any or all Critical Points to be conveniently changed It has the following form FLDPT n ON OFF TIGHT n refers to one of the Critical Points If it is absent all Critical Points are implied ON turns on the Flooding status Flooding or Tight depending whether the TIGHT parameter appears OFF sets the Flooding status to Nonflooding Effects of Flooding and Tight Critical Points RA MAXVCG and SOLVE MAX commands The procedure invoked by these commands in turn refers to the stability criterion defined by LIMIT commands When the FLD keyword is referenced by a LIMIT it implies the downflooding points represented by Critical Points with Flooding status either Flooding or Tight However any Tight Critical Points are only considered when the vessel is in equilibrium CC Command This co
37. ect launch read tanker gf report Light ship weight 6 0 97 57 19 6 85 05 14 0 85 05 22 8 5 04 20 0 5 04 21 2 2 90 vcg 5 7 Keep heel fixed assumed to be supported by side blocking heel 0 fix heel Angle of slipway inclination relative to ship s baseline trim 15a Initial depth of water at ship s origin depth 0 2 variable LS Location of aft end of slipway in ship s coordinates set LS 15 0a Initial location variable L1 Location of forwardmost block in ship s coordinates set L1 92 0f variable DL Distance between blocks in ship s coordinates set DL 6 8 variable NB Number of blocks set NB 14 End Launching Calculation Stern First Slipway inclination TRIM degrees Initial depth of water at ship s origin DEPTH Aft end of slipway relative to ship s origin LS Forwardmost block relative to ship s origin L1 Distance between blocks DL Number of blocks NB Distances in LUNIT Ship s origin is at ORIGIN variable N L D DI Generate ground points for all blocks macro blocks ground Block N 0 L 0 0 set N N PLUS 1 set L L PLUS DL set N 1 set L L1 blocks NB macro err Error 1 wait Find depth increment for each step set DI SIN TRIM set DI DI TIMES DL Find location of aftmost block set L NB MINUS 1 TIMES DL PLUS L1 if L
38. en directory named CSI_SYS CFG This directory is located either on the same drive as specified in the TEMP or TMP environment variable if it exists or else the first available drive letter starting with C As such the GHS configuration directory is normally C CSI_SYS CFG A problem can arise in network installations where access to the root of local hard drives is restricted In such cases the GHS configuration directory may not be created causing problems such as failure in the GHS ENTER SE command The solution is for network administrators to create a CA CSI_SYS CFG directory with read write access on every restricted access computer that uses GHS cacca en en een en oem om no e no oom 0 PASTING GHS32 PLOTS INTO YOUR OWN DOCUMENTS 2 2000 With GHS32 s Windows based printing you can now save plots to files in Encapsulated PostScript EPS format manipulate them using an image editing program and then insert them into a word processing document Here s how 1 2 Click Start Settings and Printers to open the Printers window In Windows 95 98 double click Add Printer in the Printers window Click Next choose Local printer then click Next again Choose a PostScript printer in the list use HP LaserJet 4P 4MP PostScript under manufacturer HP if available and click Next Choose the port FILE and click Next Call the new printer EPS File make sure it is not your default printer a
39. ersely proportional to void volume Volume Varies Nominal volume is where pressure 1 atmosphere Surface Parallel to external waterplane Weight Adds to ship s total weight Free surface Adds to total FSM Balanced Mode Vented Pressure of gas at top constant at 1 atmosphere Volume Varies Weight Subtracts from ship s buoyancy Tank Types Intact Type Unconditional Constant Volume Mode Frozen Type Unconditional Frozen Mode Surface orientation is set parallel to external waterplane at time of TYPE or LOAD Spilling Type Ref Pt above interior level Const Volume Mode Ref Pt at interior level Spilling Filling Mode Ref Pt below interior level never Bubble Type Unconditional Balanced Mode Sealed Damaged Type Ref Pt above water Same as Spilling Type Ref Pt below water Same density as external Flooded Mode Different density Balanced Mode Vented Flooded Type Unconditional Flooded Mode Side Effects of Type Changes When the tank Type is set by the TYPE command Nominal volume remains unchanged Contents also remains unchanged except as follows TYPE FLOOD sets Contents density equal to external density and Contents description to SEA Changing Type from FLOOD to another Type restores the original Contents density and description which were in effect prior to the TYPE FLOOD command Note These side effects did not exist in versions prior to 6 20 Equations of Pressure Balancing The tank Types BUBBL
40. es in a plane parallel with the external waterplane Other tank types may have variable volumes but there is always a Nominal volume associated with each tank For an Intact tank the actual volume is the same as the Nominal volume Nominal volumes are always set by the LOAD command and remain as set until changed by another LOAD command Since some tank Types involve complex behavior it is useful to refer to the Mode in which a tank is operating Following is a list of the tank Modes and Types Tank Modes Constant Volume Mode Volume Equal to the Nominal volume Surface Parallel to the external waterplane Weight Adds to the ship s total weight Free surface Adds to the total FSM Frozen Mode Volume Equal to the Nominal volume Surface Fixed at a prescribed orientation Weight Adds to the ship s total weight Free surface None Spilling Filling Mode Volume Varies Surface Passes through Tank s Ref Point amp Parallel to external WPL Weight Adds to the ship s total weight Free surface Adds to total FSM Flooded Mode Volume Varies Surface Coincident with external waterplane Weight Subtracts from ship s buoyancy Definition Balanced Internal and external pressures are equal at tank s Ref Pt External pressure is determined by Ref Pt depth Internal pressure is determined by the gas at top plus column height Level within tank not allowed to go below Ref Pt Balanced Mode Sealed Pressure of gas at top is inv
41. f all tanks The means by which a lower bound is placed on the total FSM is the FSMFLOOR command This command can also be used to place minimum values on the total FSMs of all tanks sharing the same contents It has the following form FSMFLOOR contents FSM n FSMFLOOR OFF Without the contents parameter this command sets the overall FSM floor With the contents parameter a floor value is established for all those tanks which have the indicated contents The keyword FSM specifies that the present total FSM is to be assigned as the lower bound n sets the lower bound to the given value The OFF parameter sets all fsmfloor values to zero GHS can perform an FSM like modification to the C G during a righting arm calculation while still calculating the actual C G shifts within tanks This feature is enabled through the EXTRAFSM parameter on the RA and SOLVE MAXVCG commands lt uses the difference between the formal and true FSM but not less than zero to raise the C G Updating Old FSM Commands GHS versions prior to 6 16 used a command called FSM alias USERFSM and the parameters MAXFSM and USERFSM on various other commands These have been deleted since the new FSM command together with the FSMFLOOR command accomplish the same purpose more directly Following are examples where the usage has changed Old method for applying a fixed overall FSM USERFSM n and USERFSM on various commands New method FSMMT 0 FSMFLOO
42. finition is MACRO name body where name is an arbitrary name by which the macro is thereafter referenced and body is one or more lines of text The single slash on a line by itself marks the end of the macro definition If a macro by the same name already exists it is replaced by the new definition If body is missing it is a null macro and the definition has no effect except that if a macro by the same name does exist that macro is erased this is how you delete a macro Other than storing a series of text lines the MACRO command does nothing Therefore it may appear anywhere in a command stream It is usually placed in a Run File Making use of a previously defined macro simply requires the name of the macro preceded by a dot or period Thus if a macro named XYZ has been defined XYZ will cause the text in its body to be executed as a series of commands If parameters are involved in a macro definition they are represented by the appearance in the macro body of the 2 character string n where n is a single digit 1 through 9 This is the same convention which is used by DOS in batch files For example MACRO MSDRAFT DRAFT 1 MS defines a macro named MSDRAFT which contains one line of text The 1 is interpreted as parameter 1 goes here It s sometimes called a dummy parameter If you execute this macro by saying MSDRAFT 12 then DRAFT 12 MS is the actual command which the system will recei
43. first intercept of the steady wind heeling arm and the righting arm curve is the angle of equilibrium The IMO criterion requires that the steady wind angle of equilibrium must be less than 14 degrees The vessel is rolled to windward from the angle of equilibrium due to wave action and then is subjected to a gust wind heeling arm The gust wind heeling arm is 1 5 times greater than the steady wind heeling arm The residual Area B must be greater than Area A as shown in NVIC 5 86 The USCG Severe Wind and Rolling criterion no longer makes reference to the steady wind heeling arm The angle of equilibrium is now taken at the first intercept of the gust wind heeling arm and the righting arm curve The USCG criterion requires that the gust wind angle of equilibrium must be less than 14 degrees The roll to windward while quantitatively the same as IMO is taken from the gust wind intercept and not the steady wind intercept The residual areas are then compared as in the IMO criterion Several commands are available in GHS to calculate Severe Wind and Rolling for either the IMO or USCG criteria The WIND 53 4 CD 1 2 command specifies a steady wind speed Vn of 53 4 knots at a height hn 10 meters above the water as required in the IMO criterion The nondimensional drag coefficient is specificied in both criteria at 1 2 and is set with the CD Cd parameter The HMMT WIND CONSTANT command will apply a constant heeling moment on the vessel according
44. g 11 case 0 ACCURACY CONSIDERATIONS IN SELECTING STATION SPACING 3 96 For displacers hulls a minimum station density is enforced in order to prevent accuracy problems resulting from trapezoidal integration of the section area curve The maximum allowed station spacing is 5 of the overall length which for normal area curves at maximum draft leads to displacement volume errors on the order of 0 1 It is left to the user to decide whether greater accuracy is required Decreasing the station spacing by a given factor can be expected to reduce the volume error by the square of that factor In some conditions of loading the number stations which are actually immersed may be significantly fewer than the total number of stations leaving the area curve to be represented by a lesser number of points This of course results in more error in terms of the present volume but not necessarily more error relative to the volume at normal draft Increasing the number of stations always improves accuracy but at some point the improvement obtainable by adding any more stations will be less than the errors from other sources such as the approximations involved in the station curves themselves Centers and surface properties are also affected by station spacing Waterplane properties especially the longitudinal center and moment of inertia are commonly less accurate than volumes and volume centers A particular source of inaccuracy in waterplane p
45. given inclination an equivalent of the heeling moment can be produced by moving the CG in a direction parallel to the waterplane until it comes into line with the CB This usually involves shifting the VCG Therefore if the correct GM is to be obtained from the GHS command with respect to a heeling moment the VCG must first be adjusted The GMTMMT Command The GMTMMT command takes a GMT moment as its parameter Holding the waterplane constant it modifies the light ship weight and CG such that the given moment divided by the weight equals the GMT from the waterplane The true free surface is always used GM from the STATUS Command The STATUS WPL command also will compute and display GM using the same method as the GHS command except that it does not show GM at all if equilibrium in the strict sense of the righting arm being zero is not present GM from the RA Command The RA command computes and displays GM in the transverse or direction of heeling when one of the GM LIMIT commands is in effect It will also compute and display GM on the plot in some cases even when no GM LIMIT is in effect Two cases of GM are recognized by the RA command GM at equilibrium and GM upright zero heel Whether the RA command is to deal with one or both of these GM cases is predetermined by LIMIT commands The RA process can compute GM from the waterplane or from the slope of the righting arm curve In some cases it blends a combination of both Normally
46. guage based macro which GHS implements and in the following discussion the term macro will be used to mean this kind of macro The concept of the macro is very simple a macro is a collection of commands which when the macro name is invoked causes those commands to be executed This alone is a powerful thing but its power is vastly increased when parameter substitution is performed If you know a programming language such as FORTRAN C Pascal or a modern version of BASIC you are familiar with the concept of the subroutine or subprogram or procedure depending on the terminology of the particular language These all have the ability to pass parameters which are referenced as symbols usually variable names within the subroutine Although you can also pass parameters when invoking a macro the interpretation of the parameters in macros is a little different When you define a macro you are simply storing a collection of text The system does not require that it make sense at the time it is defined Therefore your parameter substitution may take place anywhere within the macro You can even supply whole commands as parameters This leads to an extremely broad range of possibilities and is what makes the macro so powerful However one of the liabilities of the macro compared with the subroutine is that the system cannot warn you of syntax errors within the macro until it is actually executed In GHS the form of a macro de
47. lar added weight which satisfies the present stability criterion There are no restrictions on the TCG or the tank loading prior to damage on oo on e n om oo om om 0 The Q Menu System for GHS BHS and BHS Yacht 4 97 The Q Menu system can be used as an alternative to commands It enables you to perform many of the Main Program functions by making selections from menus rather than typing commands It does not apply to model building but only to the analysis phase With the menus you can select and read a Geometry File set light ship weight add other weights load tanks if applicable etc Then you can create a report showing the hydrostatic properties and stability information for the vessel in that condition The entire menu system itself consists of Main Program commands and text files That is the menus and the actions which they perform are all done with commands In fact the Q Menu files are nothing more than Run Files and text files containing documentation Therefore a user who is thoroughly familiar with the commands can modify and extend the menu system The menu system as distributed does not provide access to all of the features available through the commands If it did so it would certainly be unduly complex However as noted above it is possible to extend it and thereby to include almost any feature which you might want It is also quite easy to switch back and forth between the menu and direct c
48. lume is equal to the volume indicated by the LOAD setting The other type is called DECK It is similar to the DAMAGED type with LOAD 0 and an additional head of water added to that of the external waterplane The parameter HW must be included with the TYPE command in order to specify the value of the additional head Following is a run which demonstrates the use of these types to model the two methods of treating water on deck macro makeship clear enter pm create hull ends 0 100 top 20 bot 0 out 10 Il create deck c ends 15 85 bot 8 fit hull Il display write quit pm macro interp 1 x 2 X1 3 y1 4 X2 5 y2 6 result var name if 1 lt 2 then set 6 3 exit if 1 gt 4 then set 6 5 exit variable t set t 4 minus 1 times 3 set 6 1 minus 2 times 5 plus t set t 4 minus 2 set 6 6 div t macro wod type flood solve variable hw f v variable string u set u wunit unit mt interp HEIGHT 3 5 2 0 hw interp hs 1 5 0 4 1 f set hw hw times f if 1 NEU then type deck hw hw mac t type intact heel 0 trim 0 load 5 solve depth set f HEIGHT set v TVOLUME set f f minus 0 1 load height f solve depth set v TVOLUME minus v times 10 Deck area is v sq meters set v v times hw contents fw load weight v type flood plus Il if 1 POE then t unit
49. manner in which any stability criteria compares to proven seaworthy designs The new regulations while different from IMO s stability standards adopts the principles of IMO s severe wind and rolling criterion eee ee eee ee ee ee eee eee ee eee ee la Wind and Rolling Calculations 6 95 In the presence of wind pressure a vessel may need to have enough righting energy available to absorb the kinetic energy due to a roll from a point to the windward of its equilibrium heel GHS provides a mechanism for setting such a windward heel angle so that these energies can be compared With a heeling moment in effect see the HMMT command the equilibrium heel angle can be found simply by issuing the SOLVE command without parameters If the roll angle to windward of equilibrium is known the heel angle can then be decremented simply by giving the command HEEL r where r is the desired roll angle A more powerful way of handling the roll angle is provided by the ROLL command For example ROLL r HEEL ROLL does about the same thing as the HEEL r command except that it always moves the heel angle in the direction opposite to the initial heel angle Further if the actual value of r is to be calculated from the present condition according to the IMO rolling formula then the ROLL command may be given once in the form ROLL IMO and the actual value of r will be calculated when it is needed from the then present condition A typical sequence of
50. mmand considers only Critical Points having Flooding status DAMSTAB Command Like the RA command DAMSTAB considers Critical Points having both Flooding and Tight status but the Tight points are ignored except at the initial equilibrium DIVISION Command The DIVISION command can reference a Critical Point when the FLD parameter is used For example DIVISION FLD 2 associates Critical Point 2 with the division when it is being defined It also sets the Critical Point to Flooding status in case it was not so designated before When a Critical Point is associated with a division in this manner it prevents that point from being considered when that division is flooded during the DAMSTAB command process NOTE MAXVCG SOLVEMAX DAMSTAB and DIVISION are not available in BHS or BHS Yacht CC is not available in BHS Yacht ett kt e la Using Free Surface Moments in Stability Calculations 4 95 Applies to GHS amp BHS versions 6 36 and later A partially filled tank reduces the hydrostatic stability of the ship by virtue of the shifting of the fluid within the tank GHS and BHS account for this free surface effect by actually calculating the new C G of the fluid with each change of trim and heel Another method of representing the free surface effect is to elevate the ship s center of gravity by a suitable amount This simplifies the calculation of righting moments as a function of heel since the tank s contribution to the center
51. n GHS terminology a subdivision of the ship is called a division A division is a collection of one or more adjacent tanks compartments In essence the procedure is as follows 1 A certain load condition is set for the ship weight and CG possibly including loaded tanks 2 An accumulator variable A the Attained Index is initialized to zero 3 For a given subdivision of the ship a probability of damage P is determined by the size and location of the division The longer the division relative to the length of the ship the higher its probability of damage 4 A probability of survival S relative to the division is determined by examining the damaged stability characteristics with the division flooded 5 The product P S is added to the attained index A lt A P S 6 Steps 3 through 5 are repeated for each division 7 Steps 1 through 6 are repeated for additional load condition s and the attained indices for each are averaged A certain minimum average Attained Index is required by the rules based on the ship s size The actual procedure is somewhat more complicated since it can look at fractions of a division being flooded independently as well as multiple divisions being flooded together Note that it is inherent in this procedure that all subdivisions of the vessel need not be included in the analysis as long as the Attained Index reaches the minimum required value How to Compute a Subdivision Index with GHS The first ste
52. nd click Next Choose No when asked whether you want a test page then click Finish If your Windows installation files are not present on your hard drive you will now be asked to insert your Windows installation CD or a floppy disk Wait until the printer EPS File appears in your Printers window Right click on EPS File and choose Properties Select the PostScript tab and click the triangle next to PostScript output format then choose Encapsulated PostScript EPS Click OK to close Your system is now configured to produce EPS file versions of GHS32 printouts In GHS32 enter PRINT CONFIGURE to get a pop up window click the triangle next to the Name field choose EPS File and click OK to close This print method will be used by GHS32 until it exits but when GHS32 is restarted the Windows default printer will be restored for GHS printing Be aware that each EPS file corresponds to a single page of printed output so if your report is more than one page long an error message will be displayed and only the first page will be saved in the EPS file To get an EPS image of a particular plot within a multi page report make a backup copy of the PF file edit it with a word processor delete everything before the PLOT PAGE line for the page you want to save delete everything after the next END PAGE line and save as a text file In GHS32 enter PRINT followed by the name of the PF file to print When a window pops up to ask for the location of
53. ng moments arise from sources other than wind pressure Independently calculated heeling moments are specified directly through the HMMT command no other commands are required Internally computed wind heeling moments require two preliminary steps before the HMMT command is invoked 1 A representation of the vessel s lateral plane must be present in the geometrical model While all buoyant parts are automatically included in the lateral plane there may be other elements of the vessel which do not have significant buoyancy but which do have significant areas subject to wind pressure or lateral water pressure These may be included in the model as parts with Class SAIL even if they are under water such as a plate keel SAIL parts are ignored when computing buoyancy but their lateral projections are included with the lateral projections of the other parts of the model tanks of course are ignored when computing the lateral plane 2 The WIND command which specifies the wind pressure must be executed This command takes either a nominal wind speed referred to 10 meters above the water surface or a pressure vs height function given by means of sample pressures at given heights In the case where the wind speed is given a drag coefficient may also be given in order to match the resulting wind pressure profile to a desired standard After these preliminary operations the HMMT command may be issued in the form HMMT WIND C2 3 CONST
54. o organize general purpose macros into separate Library Files so that they may be more conveniently used in any job In other respects a Library File is no different from any other Run File When executing the GHS program from DOS you can indicate that you want to have it read a given Library File by including the file name after the L parameter For some people the best way to learn about using macros is to simply experiment with using them Others learn better by studying examples Examples of macro Library Files can be found in the GHS distribution files which have the file name extension LIB ae mm e e n m m n tt 0 Building a Swath 4 95 Part Maker is capable of assembling components into complex models The following example is a run file which builds a SWATH starting from two files STRUT GF and HULL GF which contain single component models of the strut and the pontoon hull respectively both are assumed to be symmetrical about their own centerplanes It is assumed that the part name on each file is HULL so that one of them will have to be renamed before the other file is read The techniques demonstrated here can be extended to much more complex situations READ FILE This file contains one strut as a part named HULL CREATE TEMP In order to avoid a part name conflict we now CLASS HULL effectively rename the strut part from HULL to TEMP COMPONENT TEMP SHAPE HULL HULL DELETE
55. of gravity is considered to be fixed The amount by which the C G is elevated may be chosen such that the additional righting moment produced by a small change of heel is the same as would be produced by the shifting of the tank s contents This elevation of the C G multiplied by the weight of the ship is called the free surface moment or FSM The primary disadvantage of using the FSM is that it does not accurately represent the tank s effect on stability beyond a small increment of heel since the FSM itself can be very different at different heel angles Applications of the FSM In the past the primary advantage of using the FSM was its relative simplicity and although the availability of high speed computers has made that less of an issue today there remain some applications where the FSM is still a useful shortcut One such application uses maximum FSM values to represent the free surface even in a case of loading where the true FSM is less than maximum The intent is to make a few sample cases representative in a worst stability sense of all the various loads which would occur during normal operation Another application where the FSM is necessary is in the use of precomputed maximum VCG data for a quick stability check In order to use maximum VCG data to assess the stability of a particular load case the effect of slack tanks is conveniently and quickly represented by the FSM The present VCG is increased by an FSM adjustment before
56. of the function is specified by the keyword TRUE This is the default form of the FSM functions before the FSM command is issued Three options are available in specifying the constant form One is simply to give the FSM value directly The other two use keywords PRESENT uses the present FSM value at the present load heel and trim MAX first finds the maximum FSM value of all loads at the present heel and trim and makes that the present load It then takes that FSM value for the constant This cannot be used for f2 unless fl is also MAX The UNCONDITIONAL parameter modifies the constant function forms which by default are actually constant only when the load is greater than zero and less than 1 0 This parameter makes the constant absolute so that the same FSM value is used even in the empty and full conditions Because the FSM function does not always represent the true FSM except in the variable or TRUE form the value given by the function is called a formal FSM value In the case of flooded and frozen tank types the FSM value is regarded as zero even if a constant formal FSM has been assigned The STATUS FSM command shows the FSM values yielded by the FSM functions in the current condition and marks with an asterisk those which depart from true FSM values STATUS TRUEFSM shows true values for all tanks regardless of what the formal values might be The total FSM in any condition is determined by summing the FSM values o
57. ommands Installation These simple steps will install the Q Menu system 1 Copy all files in the Q MENU distribution to the directory which contains your GHS KEY file This is normally your GHS or BHS program directory The Q MENU files are normally distributed on one of the GHS or BHS distribution diskettes in which case they will be copied to the GHS or BHS directory along with the other during installation 2 Rename the file QMENU LIB to MENU LIB 3 If there is a file with the extension LIB and the name of the main program e g GHS LIB either delete it or make sure that it does not redefine the F function key If such a file is present in the program directory it will be run when the main program starts Starting up the Menu System 1 Make the directory folder which contains the Geometry File you wish to use the current directory This can be done before running the main program by opening that directory Or it can wait until after you have started the main program see step 3 2 Run your main program GHS BHS or BHSY 3 If you have not already done so in step 1 change to the directory which contains your Geometry File using the CHDIR command You can find out the name of the current directory by using the PROJECT command This sets the project name to the name of the current directory 4 Unless it has been changed through the action of an initialization Run File such as GHS LIB the F9 key will start up the menu system
58. only by hypothetically moving the CG to a position in line with the CB GM from the GHS Command The GHS command when issued without a draft parameter computes and displays GM at the present waterplane It uses the waterplane method If free surface is present it is taken into consideration when calculating BM not BG If there is a formal FSM which differs from the true FSM the formal FSM is used unless a TRUEFSM parameter is present The GHS command does not produce or require equilibrium If the present waterplane is not one of equilibrium hypothetical TCG and LCG coordinates are assumed which put the CG in line with the CB The VCG is not changed Heel axis rotation is ignored GMT is always in the ship s transverse direction and GML is always in its longitudinal direction The GHS command does not involve the magnitude of the ship s weight only the vertical position of its CG Therefore the present waterplane need not have a realistic relationship with the weight or center of gravity in order to show GM In the presence of a heeling moment equilibrium can exist in the sense that the heeling moment equals the righting moment In order for there to be a righting moment CG and CB must not be in line Therefore the sort of equilibrium demanded by GM does not exist The GHS command ignores heeling moment It creates its hypothetical equilibrium as described above regardless of whether equilibrium with the heeling moment exists At any
59. p is to define the division geometry since GHS needs to know what are considered divisions It does not assume that each tank and compartment is an independent division Normally each double bottom tank should be included with at least one other compartment rather than being a division by itself For defining divisions use the command DIVISION n TankList AWING b HBHD v which assigns a unique number n to the division which involves those tanks listed by name If the division includes a wing tank then the WING parameter should be used along with the wing breadth b as defined in the IMO rule If a horizontal bulkhead is present above the waterline and capable of limiting the flooding when not damaged its height relative to the baseline can be indicated with the HBHD parameter When performing the probabilistic damage procedure GHS sorts the divisions into order according to their forward longitudinal locations It then proceeds to use the divisions from bow to stern After completing the survivability analysis using the first forwardmost division it takes the next division which starts at or after the aft end of the present division Hence any overlapping division will be ignored For this purpose the nominal forward and aft ends of the division are used The nominal ends are the same as the actual ends taken from the geometry unless the FWD and AFT parameters are used with the DIVISIONS command to set nominal ends at other locations B
60. perators available with the set command it is possible to customize GHS to perform hydrostatic calculations for almost any situation ae e mn n sense zecca 0 Evaluating Vessels for Weather Criterion 46 CFR 170 170 6 98 GHS is capable of evaluating the stability of a vessel based on the Weather Criterion 46 CFR 170 170 This criterion assumes that the righting arm curve has the form of a sine curve and the heeling arm curve has the form of the cosine as shown in 1 and 2 where P wind pressure A projected lateral area H the vertical distance from the center of the projected lateral area to the center of the underwater lateral area W displacement phi 14 degrees or the angle at which one half the freeboard to deck edge is immersed whichever is less The angle at which the heeling arm curve and righting arm curve intersect is the angle of equilibrium Therefore at equilibrium The Weather Criterion requires that 4 must be satisfied for each condition of loading and operation Three LIMIT commands are required by GHS in order to apply this criterion The first LIMIT command assures that the angle of equilibrium occurs before 14 degrees or the angle at which one half the freeboard to deck edge is immersed whichever is less It is defined as follows LIMIT 1 ANGLE from EQU to ABS 14 or HF gt 0 The HF keyword short for Half Freeboard refers to the angle at which one half the free
61. project gf then makesv else read macro getarea Sets the area veriable to the area under the RA curve Assumes one LIMIT AREA in effect variable area heel 0 ra 0 5 lim att noprint set area limmarg div 100 plus 1 minus toparea macro getangle Sets the variable t to the angle of the given condition RAO DI FLD variable t limit 1 angle from 0 to 1 gt 0 heel 0 ra 0 10 lim noprint set t limmarg macro gethz Computes HZ 1 according to CFR 171 055 g usingf the given angle The area variable is used for I variable t1 set t1 1 times 2 set t1 sin t1 times 14 3 set t1 1 div 2 plus t1 set HZ 2 area div t1 macro truncate if toparea gt 0 then exit gt gt gt gt This is too small The following does not apply You must determine the area to truncate from the following curve ra 0 2 5 35 area set skip 1 macro begin Check angle of maximum RA variable skip toparea set skip 0 set toparea 1 getangle MAX Angle of maximum RA is t if t lt 35 then truncate else set toparea 0 if toparea gt 0 then NOTE Trunced area toparea if skip lt gt 0 then exit Get wind heeling arm variable HZW wind pressure 0 001 hmmt wind const heel 0 solve trim tcg hmmt report set HZW minus FTCG tcg 0 hmmt off HZW A x H 1000 W HZW macro hza if skip lt gt
62. range of stability is to be at least 15 degrees beyond equilibrium the limit command would be LIMIT 3 ANGLE from EQ to RAO gt 15 To evaluate the stability of a vessel based on the Weather Criterion you must also set the heeling moment You can use the WIND and HMMT commands as follows WIND PRESSURE P HMMT WIND CS where P equals the wind pressure as calculated according to 46 CFR 170 170 a The values of A and H will be determined by GHS from the model and current waterplane All superstructure that is to be included in the lateral area calculations must be modeled If superstructure is to be included in the lateral area calculations but not in the buoyant volume of the vessel it must be modeled as a SAIL part These commands will then generate the heeling arm curve as defined in 2 Following is a simple run of commands which can be used to perform a weather criterion analysis READ filename REPORT WEIGHT w I t v LIMIT 1 ANGLE from EQ to ABS 14 or HF gt 0 LIMIT 2 ABS RATIO from ABS 0 to ABS 14 gt 0 492 LIMIT 3 ANGLE from EQ to RAO gt 15 WIND PRESSURE P HMMT WIND CS HEEL 0 RA 0 2 14 LIM Water on Deck 11 96 GHS provides two special tank types for the purpose of modeling the effects of the extra burden of water on deck due to waves The first FLOODED PLUS is an extension of the FLOODED type It raises the flooded waterplane above the external waterplane by an amount such that the increased vo
63. re any files in the project data subdirectory with extensions of RF in which case their names will be listed on the screen before the prompt for the project name appears This makes it easy to pick a project name by pressing the up arrow key and moving to the desired file before pressing enter Once the project name is defined in this manner it is only necessary to give the EDIT F4 or RUN F5 command and press Enter to edit and Run the file respectively After a project master directory has been established a particular project subdirectory can be selected interactively by giving the command in the following form PROJ C PROJECTS ote that the parameter must end in a back slash This command first changes to the master directory C PROJECTS then it lists the subdirectories and prompts for the subdirectory name At this point the name can be typed in or the up arrow can be pressed to pick a project subdirectory from the list If a new name is typed in a new subdirectory will be created When any of these project directory operations are performed the program remembers the name of the project master directory subdirectory and data directory name if any Thereafter these names are implied when omitted For example PROJ 9702 Assuming that the previous commands have been issued this will change to C PROJECTS 9702 GHSDATA Similarly the command PROJ will change to the last used project subdirectory and optionally data directo
64. rea ratio as the VCG is varied slightly If the value called for in hte limit is in the discontinuity there will be no solution The VCG which puts the valley just slightly positive may be considered acceptable however with a slightly higher VCG or stronger wind the vessel would hover at the angle of the valley not capsizing further but not returning to the initial equilibrium either aeaee n a ne e e 0 Getting your Printer to work with GHS 12 97 If you are having trouble printing from GHS here are some things you can try First make sure you can print a simple text file using the printer port you have specified through the GHS command PRINTER CONFIGURE To verify this use the COPY command from the DOS prompt For example if the printer is on LPT1 COPY C AUTOEXEC BAT LPT1 You may have to do a manual page eject to get the page to finish printing This should work equally well for any printer regardless of what type it is If this does not work and you are running in windows try it from DOS mode If it still does not work the problem must be 1 The printer is not properly connected to the port you specified 2 The printer does not have a text mode If it works from DOS mode but not from a DOS window Windows probably does not have the port mapped to the printer Check your Network printer settings In Windows 95 and NT 4 0 go into Network Neighborhood and check the printer mapping First find yo
65. roperties is in determining the outline of the interpolated end of a waterplane that area which occurs after the last station cut by the waterplane but before the end of the hull This area is normally approximated as a triangle corresponding to a waterplane which narrows to a point However square ended waterplanes occur when the bottoms of the stations in the region of the waterplane ending are parallel to the waterplane e g no deadrise in the bottom combined with a zero heel angle In this case the blunt waterplane ending is determined by extrapolating the width of the waterplane at the neighboring stations Nevertheless the accuracy of this procedure is not as good as that which results from adding stations reducing the size of the area which must be determined by extrapolation This effect is most noticeable with barges which have no deadrise in one or both of the rakes It may be necessary to use 10 or more stations within the rake in order to produce LCF and KM of sufficient accuracy to appear as smooth curves when plotted as a function of draft or displacement Tank volumes centers and their surface properties are calculated using the same procedures used to find the displacement center of buoyancy and waterplane properties of the hull Therefore the same accuracy considerations apply to containers which apply to the displacer parts The maximum station spacing for tanks is the same as for hulls Therefore a tank whose length
66. ry And finally a special case is the PROJECT command without parameters PROJ This changes to the last used master directory and prompts for the project subdirectory to be entered The program remembers project directory names by recording them in a special file named GHS PRu which is located in the program directory While it is not ordinarily necessary to do so you can erase this file causing the project directory names to be forgotten by the command PROJ OFF a a nn e n en nce zen la Applying CFR 171 055 for Sailing Vessels 3 99 In applying 46 CFR 171 055 for sailing vessels the following method of doing the relevant calculations may be useful The user should check it carefully and verify that it is operating correctly It is recommended that the NOPRINT parameter on the RA commands in macros getangle and getarea be deleted during this checking Since GHS BHS cannot slice off the top of an RA curve if you have a condition with the maximum less than 35 degrees you will have to make two runs the first to get the excessive area by inspection of the RA area curve which you can then subtract from the area in the next run by giving it as the parameter on the case macro disk off proj sail erase sail gf mac makesv enter pm create hull ends 0 100 top 20 bot 0 out 15 margin 0 Il create sail class sail ends 25 75 top 120 bot 20 out 1 Il di write qu pm if not fexist
67. s also a function of ht and the geometry of the tank Thus an intuitive procedure is applied to find the solution Setting the Bubble Pressure In the case of a BUBBLE Type tank the LOAD command can also set the pressure at that load by means of the PRESS parameter For example LOAD 0 75 PRESS 1 1 sets the load and pressure such that the pressure would be 1 1 atmospheres at 75 load in the tank When the LOAD command is used without giving a value it displays the present load as well as pressure Liquid Loss Calculations The loss of liquid when one or more tanks are ruptured at known locations can be accurately calculated by using the DAMAGED type For example STATUS TANK name REFPT damage location TYPE DAMAGED repeat above three commands for additional tanks SOLVE STATUS The difference between the load in the tank s as of the first STATUS and the second STATUS is the amount of liquid lost By using a suitable macro and variables this process can be automated for more convenience For example MACRO SPILL Uses System variable TVOLUME to get VOL before amp after damage Assumes that Reference Points have been set at points of damage VARIABLE VOL TYPE INTACT SOLVE TANKS 1 SET VOL TVOLUME TYPE DAMAGED SOLVE SET VOL VOL MINUS TVOLUME _ Oil spilled from PNAME VOL CUBIC LUNIT Then SPILL tank list shows the volume lost True Downflooding Using the DAMAGED tank type it is po
68. sed a bit farther With some vessels in certain conditions it is possible to meet such a criterion and yet have virtually no stability beyond the angle of equilibrium Therefore if the criterion envisions an actual or possible operating condition it must be augmented by some measure of stability with the heeling moment in effect Possible augmenting provisions would be a minimum range of stability a minimum area or a mimumum residual righting arm Difficulties with Angle of Maximum Righting Arm The angle at which a righting arm curve reaches its maximum value can never be known precisely The reason for this is that it is a property of the derivative of the righting arm curve not of the curve itself A property such as the angle of equilibrium is an angle at which the righting arm curve is zero The angle at maximum is the angle at which the derivative of the curve is zero While a mathematical curve may have a precise derivative a curve representing data obtained by experiment always contains some degree of uncertainty Differentiation always exaggerates the uncertainty just as integration diminishes the uncertainty Whether measured by inclining a physical ship or inclining a computerized model of the ship the righting arm curve contains experimental errors which are exaggerated by differentiation Therefore the angle of maximum righting arm cannot be known with a precision comparable to the precision of the angle of equilibrium The differen
69. ssible to have a tank automatically flood when its point of downflooding is reached Such a tank behaves as a spilling tank or an empty tank if its Nominal load is zero while the Reference Point is above water and a flooded tank when the Reference Point is below water If the heel angle is such that the Reference Point is initially above water and then increased until it is below the surface the tank will go through the transition of suddenly becoming flooded Since the contents density does not change at the transition this downflooding will be more realistic if the content is seawater Hopper Spilling and Flooding Spilling from a hopper which contains a combination of seawater and a denser liquid can be simulated by superimposing two identical tanks where one contains sea water and is of the DAMAGED Type while the other contains the residual density and is of the SPILLING Type The residual density would be the difference between sea water and the denser liquid Se eee eee m m mel 0 Evaluating Vessels for Weather Criterion 46 CFR 170 170 11 95 GHS is capable of evaluating the stability of a vessel based on the Weather Criterion 46 CFR 170 170 This criterion assumes that the righting arm curve has the form of a sine curve and the heeling arm curve has the form of the cosine as shown in 1 and 2 Righting arm GM sini 1 PAH Heeling arm cos 2 W where P wind pressure A
70. t directories are located Optionally there can be a subdirectory within the individual project directory which contains all of the files relevant to GHS For example suppose that the master project directory is CAPROJECTS Then within this directory there may be project subdirectories such as 9701 9702 etc Within each of these subdirectories there may be a subdirectory for GHS files say GHSDAT The directory structure would look like the following C PROJECTS 9701 GHSDATA 9702 GHSDATA This structure could be created by the following two PROJECT commands PROJECT C PROJECTS 9701 GHSDATA PROJECT C PROJECTS 9702 GHSDATA Of course it could also be created by operating system commands Once the directory structure has been established the same PROJECT command can be used to change to the data directory In other words the new directory is created automatically if it does not exist but in any case the result is to make the given directory the current or default directory If issued from the keyboard the above commands will also prompt for a project name If you do not want a project name simply press Enter You can also supply the project name as an additional parameter For example PROJ C PROJECTS 9702 GHSDATA INTACT This would create and or change to C PROJECTS 9702 GHSDATA and also define the project name as INTACT Another automatic feature when this PROJECT command is issued from the keyboard appears if there a
71. the Print To File choose any file name and folder you want but make sure it ends with the EPS file extension e g PP EPS Once the EPS file has been created you can open it in an image editing program such as Adobe PhotoShop or ImageReady modify it such as by adding additional labels or cropping off unneded portions and save it in the desired image format such as EPS BMP JPEG GIF TIFF etc Depending upon your image format and word processing software you should now be able to insert the modified image into your word processing document For example in Microsoft Word you would click the Insert menu then choose Picture From File and select your file which could be in EPS BMP JPEG GIF TIFF or other image formats In Microsoft WordPad you would click the Insert menu choose Object click Create from File and select your file which would need to be in BMP format to work eee eee een ee ee ee ee eee nena la GM in GHS 4 96 GM the distance from the center of gravity to the metacenter is calculated in two different ways 1 from the waterplane BM BG and 2 from the slope of the righting arm curve Note that the definition of GM implies a certain equilibrium i e that the center of gravity and center of buoyancy lie on a line which is perpendicular to the waterplane By definition the center of buoyancy and metacenter always lie on such a line If GM is considered to apply ina non equilibrium condition it is
72. tiated curve which plots the slope of the original curve is typically more bumpy than the original and it may go through many more slope reversals than the original The closer you look i e the more samples or angles you take the bumpier it gets This is because for closely spaced samples the predominant difference is the experimental error an attempt to examine the fine structure of the curve finds only the noise of the experimental error Indeed if no distinction is made between the property being measured and the noise the results will be unrepeatable and bewildering Take for example a righting arm curve which actually has a ledge i e for some range of angles the arm stays constant Adding to this the experimental error you find that it is not quite constant in practice there will most likely be an angle of maximum perceived value within that range While it may be insignificant that this so called angle of maximum is not quite true in fact there is no angle of maximum in the range it may be significant that a later attempt to find a maximum in the same range comes up with a different angle due to a different stream of experimental errors This fact causes difficulty when the angle of the maximum becomes the controlling limit when attempting to find a maximum VCG which just satisfies the limit Each time a slightly different VCG is introduced a different stream of experimental errors exaggerated by the differentiation influen
73. tion file GHS CFG assassine zecca la Directory Management in GHS BHS and BHS Yacht 6 97 Note Most of these features are available only in versions 6 52C and later DIR HERE Displays the current directory path on the screen CHDIR START Changes to the directory from which the program was originally started Note The program now returns to the Start directory after QUIT CHDIR PROGRAM Changes to the directory in which the program is found CHDIR di Changes to the indicated drive MESSAGE PATH Displays the paths to the following directories Start Where the program was started Temp Where temporary files are stored Key Where the GHS KEY file was found Program Where the program files were found PROJECT path Switches to the directory indicated by the given path If the directory does not exist it is created It also records path for future reference Note path must contain at least one back slash Example PROJ CAPROJECTS 9705 This changes to the subdirectory 9705 within the master directory PROJECTS on drive C It also records these directory paths in a special file GHS PRJ so that the full path to the project directory need not be given in the future Special cases 1 If path ends with a back slash it is taken to be the path to the master directory only Example PROJ C PROJECTS This changes to the given master directory and lists the existing project subdirectories to choose from
74. to the wind speed specified by the WIND command The GUST 1 5 parameter is used with the HMMT command to specify a gust wind heeling moment 1 5 times greater than the steady wind heeling moment The ROLL IMO K k command will calculate the roll of the vessel to windward as defined in both criteria The K k parameter must be calculated by the user according to the geometry of the vessel If the K k parameter is used you must leave a space between IMO and K k or the K k parameter will be ignored The LIMITS command is used to set the appropriate stability criterion IMO Calculation Two steps are required for evaluating the IMO criterion with GHS The first step is to find the steady wind heeling arm and evaluate whether or not the steady wind angle of equilibrium is less than 14 degrees The second step is to roll the vessel to windward and apply the gust wind heeling arm to compare Area B to Area A The following is an excerpt from a run file that may be used after loading the vessel to evaluate the IMO criterion correctly STEP 1 for determining equilibrium angle lim 1 abs angle at equilibrium lt 14 wind 53 4 cd 1 2 hmmt wind const hmmt report solve ra 0 lim STEP 2 for comparing residual areas lim 1 off lim 2 res ratio from roll to abs 50 or ra0 gt 1 lim 3 res ratio from roll to fld or ra0 gt 1 wind 53 4 cd 1 2 roll IMO K 0 7 Input appropriate k hmmt wind const gust 1 5 solve he roll hmmt
75. tual GM gmact 46 CFR 170 170 Required GM gmreq Weather Criterion found to be wxsat atisfactory The above macro performs the steps necessary to check the criterion This macro assumes weight and displacement equilibrium at the time the macro is invoked The command set gmact bmt plus vcb sub vcg sets the user variable gmact to the actual transverse GM using the system variables BMt VCB and VCG When using variable arithmetic the space separator between operators is required The curly brackets are used whenever a variable name is to be used The only exception is the expression to the left of the equal sign in the set command and for the input command The sole purpose of these two commands is to assign values to variables Therefore GHS is expecting a valid variable name and the curly brackets are not required The available operators are plus add minus subtract times multiply divide power sin cos tan atan abs sqrt trunc left n cap The documentation for the set command in the user s manual describes each operator s function Only the first two characters are significant for each The order of execution is strictly from left to right If a user defined free surface moment is in effect an additional variable will be needed to calculate the free surface correction and then this value will need to be subtracted from the above Besides the declaration of a new variable say fsa the following line
76. ur printer then look at the File menu and select Capture Printer Port which allows you to assign LPT1 etc to the printer GHS cannot handle a port beyond LPT8 it only can access LPT1 LPT2 or LPT3 If your printer does not have a text mode you will have to print your GHS output files through a Windows program such as WordPad or WMGHS Windows Manager for GHS If the COPY test does work try the following assuming LPT1 and HPLASER for your printer type substitute your actual printer type for the HPLASER keyword PP C AUTOEXEC BAT LPT1 HPLASER If you are not sure of the available printer type keywords you can get a list on the screen by typing PP alone without any parameters If this works you can certainly print text from GHS To test the graphics printing try the PPTEST BAT which came with GHS For example 1 Go to the DOS prompt and change to the GHS directory e g CD GHS then enter PPTEST HPLASER LPT1 Note that the order of the parameters is reversed from the order required by PP This should print a page which is a combination of text and graphics There should be a rectangle near the middle of the page which measures 2 x 2 If this works you can certainly print text and graphics from GHS Make sure that you give the same printer type keyword and port in response to the PRINTER CONFIGURE command You only have to do this once unless you change printers or ports since GHS records the printer type and port in its configura
77. ve Consider another example MACRO LOAD TANK 1 TYPE INTACT CONTENTS 3 LOAD 2 This might be executed by LOAD FO1 P 95 SW yielding the command sequence TANK FO1 P TYPE INTACT CONTENTS SW LOAD 95 Note that even though the macro is named LOAD the same as the name of an intrinsic command there is no confusion since a macro invocation is distinguished by the leading dot Also note that the dummy parameters can occur in any order within the body of the macro definition At execution time the order in which the actual parameters are given determines their identification with the 1 2 etc within the macro body If there are more dummy parameters in the body than there are actual parameters given at the execution the missing parameters will be considered to be empty and the result of the substitution is that the extra dummy parameters are removed For example MACRO WT TANK WINGTK 1 2 WT 3 S yields TANK WINGTK3 S while WT 3 yields TANK WINGTK3 A very important ability of GHS macros is that they can invoke other macros For example MACRO LDWT WT 1 TYPE INTACT LOAD 2 CONTENTS FO MACRO LDWT1 3 LDWT 1 1 LDWT 2 1 LDWT 3 1 and the execution LDWT1 3 98 would put 98 fuel oil in three pairs of tanks As another example consider the following macro MACRO HEADING PAGE yams Condition 1 This would work fine if you passed it a single word such as HEA
78. vy criteria are not necessarily appropriate for every type of vessel inevery loading condition and in all types of service Additional limit commands and or changes to the parameters as shown above may be needed in order to guarantee adequate stability A value attained for the RISE limit A can be converted to the value of the ratio of righting arm at equilibrium to righting arm at max B as follows B 1 1 A For example A 0 667 yields B 0 6 A value attained for the ABS RATIO limit A can be converted to the value of the ratio of residual area to total area B as follows B 1 1 A For example A 1 667 yields B 0 4 To allow for off center weights the transverse center of gravity can be set to an appropriate value If it is desired that the transverse center of gravity of the total weight including tanks be 0 05 the following command can be used WEIGHT TOTAL 0 05 This will set the transverse componenet of the light ship CG such that the overall TCG comes out to be 0 05 Since the MAXVCG command ignores the TCG as well as tank loads this will not affect MAXVCG curves HOW TO PRINT TO A NETWORK PRINTER FROM MS DOS BASED PROGRAMS UNDER WINDOWS NT adapted from Microsoft Support Article Q154498 dated October 20 1997 5 98 By default most MS DOS based programs print directly to either LPT1 or LPT2 However under Windows NT the output is not automatically routed across a redirector to a shared network
79. waterplane in question This could also have been accomplished by giving a weight and center and adding tanks and fixed weight loads The variables to be used are declared gmreq and gmact will be used for the required GMt found in accordance with 46 CFR 170 170 and the actual GMt computed by GHS respectively windmom will be the total wind moment based on the lateral projected area and pressure and tanang will be the tangent of the limiting angle 14 deg or the angle to half freeboard whichever is less wxsat will be used to display the results after gmreq was checked against gmact The following macros should be used if several stability criteria are being checked within a single run file The first clears any existing limits then sets an angle limit from 0 deg to the lesser of 14 deg Or angle of half freeboard This single limit as defined will cause GHS to set the system variable limmarg to 14 deg or the angle to half freeboard whichever is less whenever a righting arm calculation is performed and limits are evaluated macro 170170 limit off limit title USCG Weather limit angle from abs 0 to 14 or hf gt 0 macro 170calcs set gmact bmt plus vcb sub vcg wind pressure 0 005 P 0 005 L 14200 2 hmmt wind const hmmt report set windmom hmmt hmmt off rah lim at notab set tanang tan limmarg set gmreq windmom div displ div tanang if gmact gt gmreq then set wxsat S else set wxsat Uns Ac
80. y this means divisions which do overlap can be made acceptable See the DIVISIONS command in the GHS User s Manual for more details After all of the divisions have been defined the Attained Subdivision Index in the current loading condition may be obtained by the command DAMSTAB DivList L L1 L2 B B H Hmax SDIC which computes and displays the probability of damage and probability of survival for each damage case as well as the attained index If DivList is present it specifies the divisions used otherwise all of the defined divisions are used If the L parameter is present it specifies the terminal points of the Subdivision Length otherwise the overall model length is used If the B parameter is present it specifies the Subdivision Breadth otherwise the maximum breadth of the model is used If the H parameter is present it specifies the maximum possible vertical extent of damage above the baseline otherwise the same is computed as a function of the Subdivision Length Following is an example of a subdivision index Run File PROJECT CARGO1 DIV DIV DIV DIV DIV 1 workspc c fwetk c apt c AFT 107 3 DIV no2dot s btmineng c enginrm c FWD 82 9 hold5 c no4wbt s void5 s AFT 82 2 FWD 69 6 fwt s void4 s no4wbt s hold4 c AFT 69 6 FWD 56 3 WING 3 0 no8wbt s no2wing s void3 s hold3 c AFT 56 3 FWD 43 WING 3 0 no3wbt s no1wing s void2 s hold2

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