# HST

The HST program is the **Wolfson Unit's Hydrostatics, Stability and Tank Capacities Program** allowing both the definition of hull geometry and also the calculation of the standard hydrostatic and stability parameters of a vessel as well as tank capacity data.

HST and its additional modules HST Loading and HST Damage are currently used by the UK MCA (Ensign Division) for checking all third party stability submissions.

All of our software packages (except freeware) come with free unlimited software help, direct from the Unit’s staff of engineers. Optional support contracts are available covering technical help, training and consultancy.

**1. Is the program verified by a third party?**

The program is not officially approved by any authority. However, our programs is currently used by the UK MCA (Ensign Division) for checking all third party stability submissions, we also have several other National Authorities as users of the programs, and one copy used by Lloyds Register. As far the Wolfson Unit is aware of, no submission from any of our almost 200 customers for Hydrostatic programs has been refused on the basis of the software itself.

**2. How can I edit the X,Y,Z coordinates for a 3D sounding pipe ?**

While editing, if you view the sounding pipe in profile or plan (View->Profile/Plan menu item) then you will be able to edit the appropriate X,Z or X,Y information of the pipe respectively.

**3. Can I customize the output of tank capacity calculations ?**

Yes, via the ‘Tank or Compartment Conditions’ dialog, Output tab. The Output Columns grid data specifies how the layout of the data is presented in the Main HST window. The first two output columns of sounding and capacity are constant and cannot be altered. The others columns can be edited appropriately.

**4. Does HST take into account trim and heel when doing tank capacity calculations ?** Yes, capacity calculations can be performed across a range of trim and heel angles. Trim and heel ranges can be set via the ‘Tank or Compartment Conditions’ dialog, Tank Capacities tab. The latter dialog allows to enter the coordinates of the base position for the sounding pipe. The tank capacity tables include Sounding Corrections (in cm) across the required range of trim and heel angles.

**5. Is there a quick way to draw tanks having a circular section with a transverse (i.e. port/starboard) orientation?** Yes, a transverse cylindrical tank can be generated as a bow thruster within a box. The latter is needed to define the port/starboard boundary of the cylindrical tank and should be deleted afterwards.

**6. Can I calculate the effect of liquids in tanks over the full range of heel angles in HST ?** Yes, use the Damage Stability option, with the displacement condition including tank content, and set the tank to have a Fixed Volume. The stability calculation then allows for the correct movement of the liquid at each heel angle and trim.

**7. Is there a recommended digitiser to use with HST ?** WE use a GTCO Calcomp Drawingboard VI, and run it using the GTCO Calcomp TabletWorks™ drivers, which should be provided with it and must be installed for a digitizing tablet to work. The direct link to download the drivers is http://www.gtcocalcomp.com/supportdigitizing.htm and click on the appropriate manufacturer and continue to the Driver and Software Downloads.

**8. How do I draw a circular moonpool in HST ?** For a simple cylindrical moonpool, follow the same approach you would use when drawing bow thrusters. The process is thoroughly described in the ‘Bow Thruster Hole’ topic in the HST online help. In order to generate the moonpool Volume Element, three sections should suffice, i.e. A-1, A and A+1. For a more complex shape, we would advise increasing the number of sections to give a more precise definition of the complex shape. More sections will usually give more accuracy.

**9. Is there a shortcut to calculate the volume of an element which is part of the ship's hull ?** Yes, there is. First, copy the element via Ctrl+C or Edit, Copy. This will bring up the ‘New Element’ dialog, where the element being copied should be set as a new compartment, say ‘newComp’. Secondly, calculate the volume of ‘newComp’ via Calc, Tank Capacities: the required volume will be shown as ‘Capacity as 100%’ in the Tank Capacity Data sheet.

**10. Can I export a Results page to a Microsoft Excel spreadsheet ?** Yes, right-click anywhere on the Results page and select the ‘Export to Excel’ option in the pop-up menu. The main output should be correctly imported as numeric, unless there is a default setting in your Excel set up. The ‘Export to Excel’ procedure has been tested on Excel versions up to 2007.

**11. Can I fix geometry errors for an entire set of sections ?** Yes, provided that the sections of the set are contiguous. First, go to the Edit Element dialog, left-hand side table, Description column, and left-click the first, i.e. aftermost section of the set. Then left-click the last, i.e. foremost section of the set while pressing the ‘Shift’ key: this will select the entire set. Finally, go Tools, Fix Errors and select the required option. All sections of the set will be fixed at once.

**12. How can I prevent negative Bonjean curves ?** A decreasing Z-order (i.e. deck to keel) for the points of a section results in the Bonjean curve for the section being negative. The solution is to fix this error via the Reverse Point Order option in the Edit Element dialog, Fix Errors menu. If Bonjean curves are negative across a range of sections, the process may be done just once: see HST FAQ no. 11 'Can I fix geometry errors for an entire set of sections ?'.

**13. In my HST Damage file some floodable compartments are shown in blue, others in black. Why is that ?** HST Damage shows Floodable Compartments' sections in blue or black according to their parent element being the main Hull or a Compartment, as per Hull/Compartment definition in the Floodable Compartment dialog. If a Flooded Compartment derives from the main Hull, their sections are shown in blue. If the parent element of a Floodable Compartment is a compartment, its sections are shown in black.

**14. In my Hydrostatics Report the Draught at Mid Marks and the Moulded Draught are very different for large trims.** In general, one should not expect the Draught at Mid Marks and the Molded Draught necessarily to be the same. The Draught at Mid Marks is the input draught relative to the draught datum at mid marks, that is the value entered in the Hydrostatics & Stability dialog if the ‘Draught at Mid Marks, Trim Over Marks’ option is chosen. The Moulded Draught is the height of waterplane above Vertical Datum (Z=0) measured at X=0. Hence, the two draughts will be close if midships is used as longitudinal datum. However if X=0 is, for example, the longitudinal position of the Aft Marks, the Moulded Draught will be the vessel’s draught taken at Aft Marks. The difference between the two draughts will therefore be large for large trims.

**15. How can I plot Bonjean curves ?** Plotting Bonjean curves requires Wolfson Unit’s GoPlot program and a .dat file obtained from HST. A .dat file can be obtained as follows. In HST open the Edit Element window for the Element you require Bonjean curves of. In the Edit Element window select View > Offsets and Hydrostatics which will bring up the 'Hydrostatic Information' results page. Then, on the 'Hydrostatic Information' results page select Results and ensure the ‘Hydrostatics to Draughts’ option is selected. Now the Hydrostatics Information results page should present the default table of sectional properties at zero trim and zero draught. The required draughts and trims can be set by selecting Edit > Draughts and Trims. A Bonjean File (.dat) can now be saved by clicking Results > Save in the Results window.

**16. My Stability Report shows a downflooding/margine line angle as ‘EXPOSED’. What does it mean ?** A downflooding angle is ‘EXPOSED’ to starboard or port when the corresponding downflooding point never gets submerged as the ship heels from 0 to +180 degrees or 0 to -180 degrees respectively. This also applies to margin line points, in both intact and damage stability. For example, if a downflooding point on the starboard side of a vessel has a relatively low freeboard and the vessel itself has enough buoyancy above the downflooding point height, then it is likely to be ‘EXPOSED’ to port.

**17. My vessel’s equilibrium list angle is zero. However, in the Intact Stability Report the waterline at zero degrees heel and the equilibrium draught do not agree.** The two values do not necessarily match, as they may be calculated from different vertical datums depending on the vessel’s setup. Waterlines are measured from Z=0 whereas the equilibrium draught is measured from the draught marks datum line, ie line through the set draught marks. Please see an unmodified testhull file, where the two vertical datums coincide at mid marks.

**18. As I change my vessel’s loading, waterline at zero degrees heel and equilibrium draught do not change by the same amount.** The two values do not necessarily change by the same amount for a given loading variation, as they may be calculated at different longitudinal locations depending on the vessel’s setup. Waterlines are measured at X=0 whereas the equilibrium draught is measured at mid marks, so they would change the same amount only if the initial and final trim coincide or the Mid Marks X is 0.

**19. My maximum KG calculation is very slow, can I make it faster?** Select Conditions > Maximum KG and in the Options tab select ‘Calculate and Show only Summary for Conditions Results’. This option provides pass/fail results only and does not involve KG iterations. Should you require maximum KG results, then reduce the extent of the test matrix eg draught, trim and heel angle range. The latter option is particularly effective for catamarans. At large angles, at some stage during the iterations, a catamaran might be in the situation where only the bridge deck is at the waterline, with one hull submerged and the other out of the water. The low waterplane area will not be conducive to accurate iterations and might even prevent a solution being found.

**20. I want to calculate Maximum KG on Loading Conditions. How do I enter wind heeling moments and heeling lever curves for criteria nos. 11-12-13-17-19-20?** Go to the Conditions tab of the Maximum KG dialog and click the ‘Copy Loading Conditions’ button to copy the conditions set in the Weights and Loading window. You can then enter the relevant heeling moments and/or heeling lever curves for each condition. The program will use such data for calculating Maximum KG and Loading Stability Book for the Loading Condition(s) required.

**21.**** In the hydrostatic results table the LCG is presented against draught.** LCG is a function of the weight distribution and does not depend on draught. The LCG column in the report, however, indicates where the LCG needs to be in order to balance the vessel in equilibrium when the vessel is trimmed.** **At level trim LCG = LCB. At any other trim, the LCG will be vertically in line with the LCB, but a different distance along the vessel when measured parallel with the baseline. The table presents the location of the LCG in ship axes.

**22. My hull is defined in separate elements oriented longitudinally. Which one should be set as reference element for Cp and Cm?** The software assumes that the main hull below the waterline amidships will be defined by a section through a single element. If the hull is defined in separate elements the program will not calculate the Cp or the Cm correctly, regardless of what element or section are specified as reference.

**23. The damage stability results present negative values for Added Volume i.e. the vessel is more buoyant than the original hull definition.** This occurs, for example, if an element with a "negative (floodable)" intact contribution has also a "negative (floodable)" damage contribution i.e. a positive permeability. The immersed volume of that space would be deducted from the hull in a normal intact stability calculation. Flooding that space, however, results in a double negative contribution which causes its unflooding, hence the vessel becomes more buoyant.

**24. Can I copy a list of weights from Excel to HST?** Yes, as long as the Excel table has the same format as the table given in the Weights and Loading window of HST Loading. So the Excel table should have a seven column layout, no headers and one row per weight. Once the Excel table has been selected via CTRL C, it may be copied to HST via Weights > Paste Weight(s) from Clipboard.

**Release changes are cumulative.**

**Release Notes for HST Version: 04.11.20.2**

HST

- Given draught and trim, the LWL of fully submerged elements was arbitrarily set to LOA and coefficients of form were calculated accordingly. This has now been changed to LWL=0 and CB=CP=CW=0.
- Given draught and trim, the LWL of elements above the static waterline was arbitrarily set to LOA and coefficients of form were calculated accordingly. This has now been changed to LWL=0 and CB=CP=CW=0.
- Given draught and trim, if multiple elements overlapped along a common waterline (eg skeg root slightly within the hull) the cumulative LWL was incorrect. This has now been fixed.
- Given draught and trim, any appendages along the waterline (eg partially immersed spade rudders of sailing yachts) skewed the calculated LWL. This has now been fixed.

**Release Notes for HST Version: 26.09.17.1**

HST, HST Loading and HST Damage

- Writing element backup files (.~lm) caused errors to users without administrator rights. This has now been fixed by adding the new main menu option: 'File' > 'Set Up Temp Folder' for setting the location of temporary HST data.
- Compliant with Windows 10 up to and including version 1703.

**Release Notes for HST Version: 02.01.16.1**

Notes for HST Release 2 may be downloaded from this link.

**Release Notes for HST Version: 10.08.15**

HST Loading

- On occasions, conducting Maximum KG calculations for heel to port on listed ships resulted in the wrong sign for the equilibrium heel angle. This has now been fixed.
- For some combinations of Maximum KG criteria, Maximum KG calculations could not be conducted on Loading Conditions, just Set Conditions. This has now been fixed.
- The calculation of Maximum KG criteria requiring set heeling moments and/or set heeling lever curves, can now only be conducted for Set Conditions, not Loading Conditions.

**Release Notes for HST Version: 20.01.14**

HST

- In the longitudinal strength routine, the calculation of the linear ends of coffin diagrams was incorrect at some longitudinal positions. This has now been fixed.

**Release Notes for HST Version: 25.06.12**

HST Loading and HST Damage

- Maximum KG Criterion 18: Crane loads. The calculation of range beyond equilibrium disregarded downflooding points. This has now been fixed.
- Maximum KG Criterion 18: Crane loads. The calculation of the residual area disregarded the second intercept of the crane heeling curve and the GZ curve. This has now been fixed.
- Maximum KG Criterion 28: Sarchin & Goldberg. Area A was calculated to the angle of vanishing stability instead of the second intercept of the crane heeling curve and the heeling arm curve. This has now been fixed.
- Added Maximum KG Criterion 32: Applied heeling curve. Refer to Maximum KG Criteria 32 in the Process Description of the HST Loading Help File.
- Added Maximum KG Criterion 33: RINA Cargo lifting. Refer to Maximum KG Criteria 33 in the Process Description of the HST Loading Help File.

**Release Notes for HST Version: 11.06.12**

HST, HST Loading and HST Damage

- When a GZ calculation failed to converge at one or more heel angles, ie ‘Ship Failed to Converge’ message shown in the HTML stability report, the GZ curve plot for the subsequent condition was incorrect. This has now been fixed.

**Release Notes for HST Version: 30.01.12**

HST Loading

- Maximum KG results for criteria nos. 11 - 12 - 13 - 17 - 19 - 20 were incorrect when calculating Loading Conditions. This occurred because zero heeling moments and/or heeling lever curves were used by the program. This did not occur when calculating set conditions that is, set up in the Conditions tab of the Maximum KG dialog. This has now been addressed, see HST FAQ 3.20 in our Software FAQ page.
- When calculating a Loading Stability Book, the Maximum KG results for criteria nos. 11 - 12 - 13 - 17 - 19 - 20 were incorrect. This has now been addressed, see HST FAQ 3.20 in our Software FAQ page.

**Release Notes for HST Version: 11.11.11**

HST

- In the Weights and Loading window, tanks’ weights and free surface moments were incorrect when working in british tons and feet. This has now been fixed.

**Release Notes for HST Version: 03.11.11**

HST

- In the Hydrostatics Report, displacements were incorrect when working in british tons and feet. This has now been fixed.

**Release Notes for HST Version: 26.10.11**

HST Loading

- In the longitudinal strength routine the buoyancy, shear force and bending moment results were incorrect when working in feet. This has now been fixed.
- Running a longitudinal strength calculation on one or more loading conditions including deadweights caused an ‘Invalid floating point operation’ error. This has now been fixed.

**Release Notes for HST Version: 07.04.11**

HST

- In the inclining experiment the calculation of GM was incorrect. This has now been fixed.
- In the inclining experiment the slope and rate shown in the graphics output did not take the last weight shift into account. This has now been fixed.

**Release Notes for HST Version: 24.09.10**

HST Loading

- The intact Maximum KG criteria provided in the .mcr files covering IMO HSC Code Annex 7 - Multihulls and Annex 8 - Monohulls were incomplete. This has now been fixed.
- The option Section > Convert Half to Full Section occasionally generated error messages inconsistent with the final geometry of the section. This has now been fixed.
- The pass/fail result of Maximum KG criterion 12: ‘GZ at wind equilibrium shall be less than A times maximum GZ’ was inconsistent with the numerical output. This has now been fixed.
- Maximum KG Criterion 17: wording has been changed to ‘HSC Code, Annex 7, 1.3 to 1.5, Multihull Wind and Wave Rolling’.

- HST Damage
- For Damage Cases with multiple conditions, excluding one or more conditions from Damage Maximum KG sometimes resulted in an incorrect output for criteria 11, 12 and 17. This has now been fixed.

**Release Notes for HST Version: 15.09.10**

HST Onboard

- Demonstration version.
- Protection system improved.

**Release Notes for HST Version: 12.08.10**

HST

- One additional decimal place is now available for the ‘Shell thickness’ parameter in the Ship Properties dialog.
- The status of the ‘Use for Auto LWL’ check box in the Element Properties dialog was not saved to file. This has now been fixed.
- Glossary: the definitions of MCT and Waterline have been expanded on.
- Automatic update alert.

HST Loading

- Conditions defined in the Weights and Loading window can now be shown on the Ship View of the Main HST window.

HST Damage

- For the condition types ‘Displacement, Trim over Marks’ and ‘Draught at Mid Marks, Trim over Marks’ the Damage Stability report showed a constant trim for all conditions. This has now been fixed.

**Release Notes for HST Version: 20.04.10**

HST

- Command line option: the program can now load HST files automatically. The command syntax can be found in the Command-Line Mode section of the HST help.
- Command line option: the HST program can now run hydrostatics, stability and maximum KG calculations automatically and save results files in the HYP, STP and MKP formats respectively. The command syntax can be found in the Command-Line Mode section of the HST help.

**Release Notes for HST Version: 24.07.09**

HST

- Maximum KG criterion 11: Weather Criterion. Areas A and B have been added to the summary data section of the maximum KG results.
- The pass/fail text output of maximum KG criterion 18: Crane Loads was not consistent with the numerical output. This has now been fixed.
- The program can now run on a client machine with a single license dongle for other Wolfson software, provided that one license for HST is available on the license server.
- A machine with a single license dongle for HST can now be connected to a license server with a network dongle for other Wolfson software.
- Dongle-related error messages have been improved.

**Release Notes for HST Version: 15.04.09**

HST Onboard

- The program can now automatically check the compliance of the vessel's draught with the allowed load line. The maximum allowed draught is automatically corrected based on the vessel's fresh water allowance and the water density. Allowed draught and pass/fail results are displayed in the loaded condition report.
- The program can now automatically check the compliance of the vessel's attitude with the allowed minimum and maximum trim. Allowed trim and pass/fail results are displayed in the loaded condition report.
- The program can now automatically check the compliance of the vessel's GM(fluid) with the allowed GM. The minimum allowed GM is interpolated from vessel-specific data, based on the actual trim and draught of the ship. Allowed GM and pass/fail results are displayed in the loaded condition report.
- The program can now automatically check the compliance of the vessel's effective VCG with the allowed KG. The maximum allowed KG is interpolated from vessel-specific data, based on the actual trim and draught of the ship. Allowed KG and pass/fail results are displayed in the loaded condition report.

**Release Notes for HST Version: 08.04.09**

HST

- The pass/fail text output of maximum KG criterion 20: UK MOD Crane / Turning was not consistent with the numerical output. This has now been fixed.
- The output of maximum KG criterion 20 has been improved.

- HST Onboard
- The program can now help assessing the longitudinal strength of the vessel. Actual longitudinal shearing forces and bending moments are automatically checked against strength requirements. Longitudinal strength tables and graphs are being displayed in the loaded condition report.

**Release Notes for HST Version: 16.03.09**

HST

- The program detected non-existent section spacing errors on small scale models. This has now been fixed.
- Some section order errors were not detected when checking the model geometry. This has now been fixed.

**Release Notes for HST Version: 11.11.08**

HST

- The optimization routines used to calculate Cross Curves and Intact Stability did not converge for certain circumstances. This has now been fixed.

**Release Notes for HST Version: 06.08.08**

HST

- The sign convention used in reports for heel angles was believed to lack clarity, eg when doing Maximum KG analyses for heel to port.Therefore, angles formerly indicated as positive are now referred to as ‘to starboard’. Similarily, negative angles are now referred to as ‘to port’.
- GZ curve tables in reports now show results at equilibrium.
- GZ curve tables in reports now show GZ Curve Areas below equilibrium. These were zeroed in previous HST versions.

- HST Loading & Damage
- The program can now perform Gross Tonnage and Net Tonnage calculations. These are referred to guidelines and formulae set forth in the 1969 Tonnage Convention Regulations.

**Release Notes for HST Version: 30.06.08**

HST

- Added 'Box, Trapezoid' to Auto Make elements list. Refer to ‘Box, Trapezoid Dialog’ in the Windows and Dialogs section of the HST Help File.
- Compliance with dual monitor setup.

HST Loading & Damage

- Added Maximum KG Criterion 29: HSC Code Annex 7, 1.1, area under GZ curve. Refer to Maximum KG Criteria 29 in the Process Description of the HST Loading Help File.
- Added Maximum KG Criterion 30: The maximum GZ up to A degrees beyond equilibrium shall be at least A metres. Refer to Maximum KG Criteria 30 in the Process Description of the HST Loading Help File.
- Added Maximum KG Criterion 31: The freeboard of any downflooding point shall not be less than A metres. Refer to Maximum KG Criteria 31 in the Process Description of the HST Loading Help File.

HST Damage

- Maximum KG Criterion 17 did not cover damage stability. This has now been fixed.
- Maximum KG Criterion 17: wording has been changed from ‘HSC Code’ to ‘HSC Code, Annex 7, Multihull Wind/Wave Rolling’.

**Release Notes for HST Version: 07.04.08**

HST

- When saving an .HST file making use of multiple Heeling Lever curves, only one of these was retained. As a consequence, the association between Heeling Lever curves and conditions was lost when reloading the file. This has now been fixed.

HST Loading

- When calculating Intact Maximum KG for the IMO-MODU criterion, convergence issues were found. These have now been fixed.

HST Damage

- The ‘Calculate Full Trim Effect’ option has been removed. This is because HST can now automatically trade off convergence speed and results accuracy.
- When calculating Damage Maximum KG, occasional lack of consistency was found for starboard and port calculations. This has now been fixed.

**Release Notes for HST Version: 13.11.07**

HST

- Added a Longitudinal Centre of Gravity (LCG) column to the short hydrostatics report.

HST Loading

- Added a rate (deflection/moment) column to the pendula/inclinometer readings in the inclining experiment results.

HST Damage

- A GZ Curve Area column has now been added to the Damage Stability results table.
- When calculating Damage Maximum KG with the summary only option, HST would still always iterate maximum KG. This has now been fixed.
- There is now an option for the condition type (Displacement, LCG, Draught and/or Trim) in the Floodable Lengths calculation.

**Release Notes for HST Version: 13.09.07**

HST Damage

- If the Floodable Length input displacement data is changed and then the user shows last results the new displacement data will be displayed with the previous displacement data calculated floodable length curves. This has now been fixed
- If you have a draught, trim condition in Damage Maximum KG, all the calculations will only use the trim from the first condition in the list. This has now been fixed.

**Release Notes for HST Version: 05.07.07**

HST

- There can sometimes be an error when exporting an STP file and importing it into GoPlot. This has now been fixed.

HST Loading

- In the weights and loading window; weights that are added that refer to tanks will by default be called the tank name when selecting a new tank, the name can be changed at a later stage.
- There is a change in the loading part of the file format. Older HST files will work with no problem but newer files cannot be used with older version of HST.
- Added Maximum KG Criterion 28: Sarchin and Goldberg Passenger Crowding. Refer to Maximum KG Criteria 28 in the Process Description of the HST Loading Help File.

**Release Notes for HST Version: 30.05.07**

HST

- If using a USB digitizer the communication speed was too fast for the application causing multithread errors . This has now been fixed.
- Please see below for digitizer information. The GTCO Calcomp TabletWorks(tm) Drivers must be installed for a digitizing tablet to work. The direct link to the drivers is http://www.gtcocalcomp.com/supportdigitizing.htm and click on the appropriate manufacturer and continue to the Driver and Software Downloads.

**Release Notes for HST Version: 10.05.07**

HST

- If adding a section and not using a digitizer there can be a repetitive "class not registered" error. This has now been fixed.
- Please see below for digitizer information. The GTCO Calcomp TabletWorks(tm) Drivers must be installed for a digitizing tablet to work. The direct link to the drivers is http://www.gtcocalcomp.com/supportdigitizing.htm and click on the appropriate manufacturer and continue to the Driver and Software Downloads.

**Release Notes for HST Version: 16.04.07**

HST

- There is a fundamental change to the digitizing tablet setup in HST. The change is to make connecting to a digitizer more universal and to ensure future compatibility with Vista and newer operating systems. To use a digitizing tablet with HST you must now use the GTCOCalComp TabletWorks(tm) Drivers. You must install these drivers to now use your digitizing tablet. For more information see Digitizer Setup and Configuration in the Tips and Hints section of the HST Help. For the drivers and further information go to www.GTCOCalComp.com. If you have difficulties then please contact the Wolfson Unit.
- If Margin Line points are included and checked in the Hydrostatics and Stability dialog they will be added to the list of flood points every time the intact stability is calculated. This has now been fixed.
- Showing the Graphs of Cross Curves for a displacement, LCG condition can sometimes result in an error for certain circumstances. This has now been fixed.
- For a specific set of circumstances when setting bulkheads in an element using Tank Capacities or Damage Stability within the first three sections and using trapezoidal longitudinal basis there can be a volumetric error. This has now been fixed.

**Release Notes for HST Version: 21.02.07**

HST

- When plotting the graphs the series titles are now plotted on the right hand side of the graph to attempt to avoid writing over the plotted lines, especially GZ Curves.

HST Loading

- The Maximum KG convergence calculations have been modified to increase stability and reduce the number of "failed to converge" errors.

HST Damage

- The above Maximum KG calculation modification should improve the convergence when calculating Damage Maximum KG.

**Release Notes for HST Version: 05.01.07**

HST Loading

- Added Maximum KG Criterion 27: GZ shall be positive up to A degrees beyond equilibrium. Refer to Maximum KG Criteria 27 in the Process Description of the HST Loading Help File.
- New PDF version of HST Loading paper manual uploaded to customer download area.

HST Damage

- When selecting conditions for Damage stability, the selection can now be applied to all other damage cases using the apply selection to all damage cases button on the condition tab of the Damage Case dialog. For more information see the damage case dialog.
- When selecting flood points for Damage stability, the selection can now be applied to all other damage cases using the apply selection to all damage cases button on the flood points tab of the Damage Case dialog. For more information see the Damage Case dialog.

**Release Notes for HST Version: 07.12.06**

HST

- In stability results a higher resolution stability data *.STP file may be written. This outputs the GZ curve at 2 degree intervals over the heel angle range set. See the Results window. Results, Save menu item. Select Hi-Res Stability Data file.
- New PDF version of paper manual uploaded to customer download area.

HST Loading

- For maximum KG there is now an option to limit the maximum equilibrium heel angle when iterating the KG value. This is to aid the convergence such that the vessel will remain stable (positive GM) and hence HST will not have to start the iteration again. This is not to be confused with criteria limiting the maximum equilibrium heel angle, these should be used as normal. See options tab of the Maximum KG dialog.

HST Damage

- For a damage case, HST can now calculate damage maximum KG for all intermediate stages. See options tab of the Maximum KG dialog.
- The above additional option to maximum KG has so far greatly improved convergence for damage maximum KG.

**Release Notes for HST Version: 20.11.06**

HST

- When calculating stability, if any GZ curve is not symmetrical port to starboard then the results will now give the GZ curve angle of vanishing stability, maximum gz angle and maximum gz value for both port and starboard angles of heel.
- HST relies on an HTML browser plug-in for the results page. There has been no indicated problems using the new Internet Explorer 7

HST Loading

- A new formulation for calculating GM based maximum KG criteria has been written to account for an offset TCG or asymmetry in form.
- An option has been added to the Maximum KG dialog, option tab page to turn off the full trim calculation in the Maximum KG iteration. This can greatly increase the speed of calculation but at the expense of a small loss in accuracy. Please see help for more information.

HST Damage

- When calculating Damage Maximum KG with a displacement,trim or draught, trim condition the calculation was repeated for the number of trims set in the Intact Maximum KG if an intact displacement, trim or draught, trim condition was set. This is now fixed.
- A new formulation for calculating GM based maximum KG criteria has been written to account for an offset TCG or asymmetric damage.
- When calculating damage maximum KG for more than one case the results for maximum KG can obtain an obvious error in certain circumstances. This is now corrected.

**Release Notes for HST Version: 20.09.06**

HST Loading

- After editing data in the Weights and Loading window and closing and then returning to the Weights and Loading window a confirmation of changes is sometimes requested. This is now fixed

HST Damage

- Added ability to name floodable compartments by using referenced hull or compartment group name. See the Floodable Compartment Dialog
- Floodable compartments may be sorted by alpha-numeric or by hull/compartment group order. See the Layout menu commands in the Damage Window
- All defined compartments may be inserted as floodable compartments as a batch. See the Insert, All Compartment as Floodable Compartments menu command in the Damage Window

**Release Notes for HST Version: 31.08.06**

HST

- When creating an element with 3 sections and first two sections have same X position. HST issues error [List Index Out of Bounds], this should be a hull definition error. This is now corrected.

HST Loading

- Added Maximum KG Criterion 26: The area up to A degrees beyond equilibrium shall be B. Refer to Maximum KG Criteria 26 in the Process Description of the HST Loading Help File.
- Added progress bar for longitudinal strength calculations.
- Changed longitudinal strength output format of hydrostatic data to exactly match that of the loading conditions.
- GM Solid and GM Fluid in the longitudinal strength data did not match the data presented in the loading conditions calculation. This is now corrected.

**Release Notes for HST Version: 14.08.06**

HST

- When importing GHS files (*.GF) HST now uses a scaling factor of 0.3048 to convert from feet in the file to metres in HST.
- No total limit on number of points when importing LFH,OFE,IMS and GHS files. A limit of 1000 points per section still exists.
- When a ship is defined away from X=0 the program may have difficulty in converging to a solution when calculating a displacement condition. This is now corrected.
- When editing an item in any tree view with many items, the view will now return to the selected item and not to the top of the items in the view. This is for the Main HST Window, Weights and Loading Window and Damage Window.

HST Loading

- For some tanks putting in a 0 percentage in weights and loading can result in a capacity volume greater than 0. This is now corrected.
- The tank weights output in the weights and loading window are not updated after editing a tank geometry. This is now corrected. The calculation for any loading condition was and is not affected.
- Added Maximum KG Criterion 25: Maximum Steady Heel Angle to Prevent Downflooding in Gusts. Refer to Maximum KG Criteria 25 in the Process Description of the HST Loading Help File.
- When calculating Loading Conditions or Loading Stability Book the TCG can now be set to zero when selecting the loading condition. This was the default for the Loading Stability Book calculation option.

HST Damage

- In Maximum KG, if the program cannot find a solution to the Margin Line freeboard criteria because the margin line is always above the requirement, the program now indicates this as a pass.

**Release Notes for HST Version: 30.06.06**

HST

- Indication of Tank/Compartment Configuration (Starboard,Port or Symmetrical) on icon in tree view
- Retain hull/compartment tree view expand or collapse in Main HST window
- Margin line points for intact stability - See Conditions Dialog
- View margin line points in Main HST Window
- Help files updated accordingly

HST Loading

- Retain condition,deadweights and weight group tree view expand or collapse in Loading window
- Retain window controls configuration in Weights and Loading window (e.g. window size,arrangement of lists etc.)
- Margin line points for intact maximum kg criteria 24 - See Conditions dialog and Maximum KG dialog.

HST Damage

- Addition of copy compartment group to another damage case
- Indication of Floodable Compartment configuration (Starboard, Port or Symmetrical) on icon in list
- Retain damage case tree view expand or collapse in Damage window
- Retain window controls configuration in Damage form (e.g. window size,arrangement of lists etc.)