Max KG Ship Data

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Tutorials

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Tutorial 1: Upright Hydrostatics Analysis

In this first example, we will look at computing basic upright hydrostatics of a

design imported from Maxsurf.

1. First close any design you may have open, then choose File | Open design

from the file menu. Select Hydromax Sample.msd from the Sample Designsfolder.

When prompted, select Read Sections from File and set precision to medium. Click

OK to close the dialog box. If you change to the Design window (select from themenu either Window | Profile, Window | Plan, Window | Perspective or Window |

Body Plan depending on which is the currently active view), you will be able to doa visual check of the design to ensure that the design has been loaded correctly.

2. The Upright Hydrostatics analysis option maybe chosen either from the

menu (Analysis | Set Analysis Type | Upright Hydrostatics) or from the Analysis

toolbar drop down menu:

3. To determine the Upright Hydrostatics of the vessel the program requires a

(number of) draft value(s), a VCG in m above the baseline, as well as a trim angle.

These values are set from the Analysis menu item. Choose Analysis | Trim and theTrim dialog box should appear:

Set the Fixed Trim value to 0m (it should actually be set at this by default).

Click OK to close the Dialog box.Now lets set the draft readings. Select Analysis | Draft from the menu. In the Draft

Range dialog box enter and Initial draft at amidships value of 1m and a Final draft

at amidships value of 1.3m, also set the Number of drafts to 4 (ensuring that thedraft readings are incremented by 0.1m) and leave the VCG above baseline value at

the default value of 1.215m:

4. The final set up required before running the Upright Hydrostatics Analysisoption is to tell the program which hydrostatic parameters you want displayed in the

results window. To do this first ensure the results window is the current window

(Window | Results) and select Display | Data Format from the menu. A dialog boxwill then appear with all the output options for the Upright Hydrostatic results.




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Check all the boxes and choose vertical Data Layout and LCB/LCF origin FromAmidships.

Click OK to close the Dialog box.

5. To run the analysis either choose Analysis | Start Hydrostatics from the

menu bar or work from left to right on the analysis toolbar:

From the first drop down menu item choose the Upright Hydrostatics option.

From the second drop down menu it does not matter what Loadcase is chosen as the

Upright Hydrostatics Analysis option does not require this information. Form the

last drop down menu item choose the Intact option. Press the play button, , toperform the calculations.

Return to the results window to view the hydrostatic parameters of the vessel for the4 specified draft readings:

The results may also be displayed in graphical format (choose Window | Graphfrom the menu):




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Tutorial 2: Large Angle Stability Analysis

In this example, we will look at computing the large angle stability of a design

imported from Maxsurf and compare the results with IMO stability criteria.






2. From the Analysis toolbar drop down box choose Large Angle Stability

3. The next thing to do is set up a Loadcase. Go to the Loadcase window

(Window | Loadcase). For this sample design the Lightship values have already

been entered. You will notice that there are also 4 tanks that have been entered buthave ? entered in their Weight, Long.Arm etc. fields:

Note: The tanks have already been defined in the Window | Input | Compartment

Definition window, which will be covered in a later tutorial.In order for values of each tank to appear in the weight field etc, either they can be

input manually or Hydromax can calculate the values (the tanks are assumed to befull to the percentage indicated in the Quantity column). To obtain the values from

Hydromax choose Analysis | Form Compartments from the menu (or click on the

Form Compartment button, ), the fields in the Loadcase window should now beautomatically filled in.

4. Next we want to define to the program the angles at which we want the

stability values. Go to the Analysis | Heel menu option to display the Heel Setupdialog box. In the dialog box set the parameters to those shown in the following

diagram:




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Click on OK to close the dialog box.

5. The next step is to set up the criteria that we want measured. To enter thecriteria dialog box select Analysis | Criteria from the menu or click on the criteria

button form the Analysis toolbar, . Expand the tree diagram in the left so that

the IMO A.749(18) Ch3 criteria are displayed and select the first 6 criteria by

checking the appropriate boxes.

The right hand side of the dialog box gives details and a description of the selected

criterion. In the bottom right hand corner there are two check boxes Intact andDamaged. These check boxes indicate which analysis cases the highlighted

criterion should be calculated for. For each of our criterion we want only the Intactbox checked. Press the Recalculate and close button to close the dialog box.

6. We are now ready to run the Lange Angle Stability analysis, to do this,

choose from the Analysis Menu toolbar (if you have the Body Plan view set asyour current window you will be able to see the vessel heeled as Hydromax runs

through the calculations).

7. The results of the Large Angle Stability Analysis maybe viewed in threeformats. In tabular form they are stored in the Results window (Window | Results):




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These results are also printed to the Report file (Window | Report) and appended toany previous analyses. The results may also be viewed in the form of a GZ curve,

with basic values such as Max GZ, Initial GM and the angle at which

downflooding begins marked on the graph:

To see whether the vessel passes the IMO criteria for this loadcase go to the Criteriaresults sheet (Window | Results | Stability Criteria). The required value, the

calculated value and whether or not the vessel has passed are displayed along sideeach of the criteria.

8. An interesting exercise to do is compare the GZ curve with that obtainedwhen the actual free surface moments of the tanks are calculated rather than using

the default corrected VCG method. To do this select Analysis | Fluids from the

menu to activate the Fluids Analysis dialog box. Choose the Simulate Fluid

Movement radio option:

Click OK to close the dialog box. Choose form Analysis | Form Compartmentsfrom the menu to update the loadcase. We are now ready to run the analysis using

the Start Analysis button from the Analysis toolbar, . View the results from the




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graph window. Below is a comparison of the GZ curves obtained using the twodifferent methods.

-1

-0.5

0

0.5

1

1.5

2

2.5

0 50 100 150

Heel angle (deg)

GZ(m)

Simulated FluidMovementMethod

Corrected VCGmethod

It is interesting that the corrected VCG method adopted by most classificationsocieties well under predicts the actual stability of the vessel with free surfaces.

When using the corrected VCG method the tank capacities and free surfacemoments are calculated for the upright hull (zero trim and zero heel). The effective

rise in VCG due to the tanks' free surface is calculated by summing the maximum

free surface moment of all the tanks filled less than 98% capacity and dividing bythe total vessel displacement. This method should be used when compiling a

stability booklet for a design, as it corresponds with the traditional approach used by

naval architects and classification societies worldwide. It is reasonably accurate atlow angles of heel and trim.

Use Simulate Fluid Movement when a faithful simulation of the movement of thecentre of gravity of the fluid in each tank is required. Every tank is rotated to the

heel and trim angle being analysed. Hydromax iterates to find the fluid level for the

rotated tank at the specified capacity. The new centre of gravity is calculated foreach tank and used in the analysis. The new LCG, VCG and TCG are calculated for

the whole design and used in the calculation of GZ, KG, and GM. This approach is

used when the stability of a vessel is being investigated and the closest possiblesimulation of the hull's behaviour is required. It is particularly useful at high angles

of heel or trim, or with tanks whose heeled water plane area may be significantly

different from the upright case (i.e. tall narrow tanks, or wide shallow tanks). Thepenalty of using this approach is that the calculation time is longer, however the

results are significantly more accurate.




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Tutorial 3: Equilibrium Condition Analysis

In this example, we will look at the Equilibrium Analysis of a design imported from

Maxsurf.






2. Choose Equilibrium Analysis from the Analysis toolbar (or from the menu

choose Analysis | Set Analysis | Equilibrium Condition)

3. Hydromax essentially balances the weight of the vessel with the

hydrostatic restoring force according to Archimedes principle. When theEquilibrium Analysis Condition is run the vessel is iteratively heaved, heeled and

trimmed until the buoyancy force balances the weight force, the net trimmingmoment is zero and the net heeling moment is zero. When this is achieved theresults are printed to the Results window, with the hydrostatic parameters being

displayed for that attitude. So the next step is to set up the Loadcase so that

Hydromax has a vessel displacement and centre of gravity to balance with thehydrostatic restoring force. Select Window | Loadcase from the menu. Select

Analysis | Form Compartments from the menu or click on the Form Compartments

button in the Analysis toolbar, . This will calculate the weight and centre of

gravity of the tanks in the Loadcase up to their percent capacity as defined in thequantity column.

4. We will now define a fifth tank that will be a catch tank, which is half fullof seawater. From the menu choose Window | Input | Compartment Definition. To

add a compartment choose Edit | Add Compartment or use the hotkey command

CTRL+A. Name the tank something meaningful like Catch Tank. Set the fluidtype to seawater by entering sw in the appropriate field. The Relative Density

value will be automatically updated with the default value for seawater of 1.0252.

The Aft, Fore, F Port, F Starb., F Top and F Bott. columns are all usedto define the tank boundaries, set the values to 7.5, -4, -2, 2, 2 and 0 respectively.

Leave the remaining 4 column values set at DITTO, this ensures that the aft crosssection of the tank is the same as the forward cross section shape. Now view the

tanks in the Perspective Window, . If the tanks are not displayed click on the

display tanks icon, , and display tank names icon, . You will notice that the




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Catch Tank has boundaries outside of the hull. To trim the tank to the hull surfaceyou will need to select Analysis | Form Compartments from the menu. The tank

should now be trimmed to the hull surface:

Return to the Loadcase window and set the Catch Tank Quantity column to 50%.

5. Check that the Analysis toolbar is set to Equilibrium, Loadcase and Intact.

From the Analysis toolbar, click on the Run Analysis icon, .

6. Switch to the Results window to view the output (Window | Results). Theparameters that are displayed in this window may be altered in the Data Format

dialog box (Display | Data Format). The Graph window displays the curve of

sectional areas at the equilibrium heave, trim and heel of the vessel.

The results are also printed to the Report window (Window | Report).

7. The Equilibrium Condition Analysis is a useful tool for running

simulations to determine the vessel response to various imposed conditions. Forexample we will now look at what happens to the vessel Hydrostatically in a

seaway comprised of a regular wave with wavelength 1.5 times the vessel LWL and

a wave height of 2m.

8. Activate the Waveform dialog box by choosing Analysis | Waveform from

the menu. Create a regular waveform by selecting the Sinusoidal radio button

option. Next set the wave height to 2m and the wavelength to 31.8m (1.5 times thewaterline length), leave the phase offset value at 0 (this means the crest of the wave

will coincide with the fwd end of the DWL).

9. Change view to the Perspective window ( ) and turn on the rendering

( ). Now run the Analysis (Analysis | Start Equilibrium Analysis) and watch asthe vessel is hydrostatically balanced on the wave at 20 equally spaced phase angles

from 0 to 1. The motion may also be viewed from a continuous animation, choose




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Display | Animate from the menu. If the animation is running too fast it may beslowed down by pressing the (negative) key on your keyboard.




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Tutorial 4: Specified Condition Analysis

In this example, we will look at Specified Condition analysis of a design imported

from Maxsurf. The Specified Condition Analysis calculates the vessel hydrostatics

for a given displacement and centre of gravity, or fore and aft drafts, or heave andtrim. We will also run this analysis for a vessel operating in fresh water.


from the file menu. Select Hydromax Sample.msd from the Sample Designs

folder.



Body Plan depending on which is the currently active view), you will be able to do

a visual check of the design to ensure that the design has been loaded correctly.

2. Choose Specified Condition Analysis from the Analysis toolbar (or from

the menu choose Analysis | Specified Condition). To run the analysis in FreshWater (i.e. water with a relative density value of 1.0), we need to enter the Densities

dialog (Analysis | Density).

When an Analysis is run Hydromax always performs the calculations using the

density in the Sea Water row (row number 1). Therefore to run the calculations in

fresh water of density 1000 kg/m3we need to change the relative density in row

number 1 to 1.0. Click OK to close the dialog box.

3. In the Specified Conditions Dialog box three sets of variables are provided:Heel, Trim and Immersion. When defining a condition, one choice must be made

from each of these groups. There are 10 combinations of parameters to define acondition (which are outlined below):

Fixed Heel, Fixed Trim and Displacement




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Fixed Heel, Fixed Trim and Draft Amidships Fixed Heel, Fixed Trim and Draft Fwd and Aft Fixed Heel, Free to Trim and Displacement Fixed Heel, Free to Trim and Draft Amidships Free to Heel, Fixed Trim and Displacement Free to Heel, Fixed Trim and Draft Amidships Free to Heel, Fixed Trim and Draft Fwd and Aft

Free to Heel, Free to Trim and Displacement Free to Heel, Free to Trim and Draft Amidships

In our case we will specify the displacement and centre of gravity of the vessel.

Once these two parameters are specified there is only one possible attitude the boatwill float at under equilibrium conditions. To set the Specified Conditions activate

the Specified Conditions dialog box (Analysis | Specified Conditions). When aradio button is selected the edit boxes of the parameters that are required to fully

define the condition are activated, and those that are not required are deactivated.For example if we wish to see the hydrostatic particulars and equilibrium attitude of

the boat with a displacement of 90t and a VCG, LCG and TCG of 1.2m, -2.0m and0m respectively, choose the Free to Heel, Free to Trim and Displacement radio

buttons. Enter the values into the appropriate edit boxes as outlined below:

Click OK to close the dialog box and Select Analysis | Start Specified Condition

Analysis from the menu. Hydromax will now calculate the equilibrium attitude ofthe boat and the hydrostatic parameters of the boat at that attitude.

4. Go to the Profile view, , of the boat to see the equilibrium attitude of

the boat.

The results may be viewed in the Results and Report windows and the curve of

sectional areas may be viewed in the Graph window. Have a play with changingthe displacement and centre of gravity values in the Specified Conditions Dialog

and re-running the analysis to see how it affects the equilibrium attitude of the boat.

5. We will now apply 20cm of hog to the boat at Amidships. From the menu

choose Analysis | Hog and Sag. Check the Apply Hog or Sag value option and

enter a value of -0.1m (the negative sign means it is a sag value):




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Click OK to close the dialog box.

6. Now returning to the Report Window (Window | Report) we can compare

the results with and without the 10cm of sag at amidships. Note: every time that anAnalysis is run the results are automatically printed to the output window.




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Tutorial 5: KN Calculations Analysis

In this example, we will look at the KN Calculations analysis. The KN Calculations

Analysis calculates the KN values for a range of displacements and Heel Angles.

KN data is useful for assessing the stability of a vessel in the early stages on designwhen the VCG of the vessel is not known. It is also a useful measure of stability for

vessels such as cargo ships where the VCG can vary significantly depending on theloading for a particular voyage.




OK to close the dialog box. If you change to the Design window (select from the

menu either Window | Profile, Window | Plan, Window | Perspective or Window |


2. Choose KN Values Analysis from the Analysis toolbar.

3. We now need to set up the conditions for which we require the KN values.Firstly go to the Heel Setup dialog box. We want to go from 0oto 120

oin steps of

10o, heeling in a starboard direction.


4. Next open the Trim Setup Dialog box (Analysis | Trim). Make sure the

Fixed Trim option is chosen and set to a value of 0m.


5. Finally we want to set the range of displacements for which we want to

calculate the KN values. Choose Analysis | Displacement to activate the




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Displacement Range dialog box. Set the range of displacements from 70t to 130twith the Number of displacements set to 13.

Click OK to close the dialog box

6. To begin the analysis choose Analysis | Start KN Analysis from the menu

or click on the Start Analysis icon, , on the Analysis toolbar. The results will be

printed to the results window (Window | Results | KN Values) and the Cross Curves

of Stability graph (Window | Graphs | Cross Curves). KN is plotted as a function ofthe displacement for a range of heel angles (as specified in the Heel Setup dialog

box).




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Tutorial 6: Limiting KG Analysis

The limiting KG analysis method calculates the maximum KG the vessel can have

and still pass the selected criteria. Calculations may be made with either the vessel

free to trim as it heels or fixed in trim as it heels.

1. First close any design you may have open, then choose File | Open designfrom the file menu. Select Hydromax Sample.msd from the Sample Designs

folder.

When prompted, select Read Sections from File and set precision to medium. ClickOK to close the dialog box. If you change to the Design window (select from the

menu either Window | Profile, Window | Plan, Window | Perspective or Window |Body Plan depending on which is the currently active view), you will be able to do


2. Choose Limiting KG Analysis from the Analysis toolbar.

3. Next we need to set up the criteria for which we wish to find the maximum

allowable KG for which the vessel still passes. From the menu choose Analysis |

Criteria or select the criteria button from the analysis toolbar, . In the left hand

side of the Criteria window expand the tree along the Criteria/ IMO/ MSC 36 (63)HSC Code/ Ch2 Monohulls/ HSC mono. intact branches. Select all 7 of the listed

criteria by checking the appropriate boxes:

Click on the Recalculate and Close button at the bottom right hand side of theCriteria window. Before calculation a range of displacements needs to be input.

From the menu choose Analysis | Displacement to activate the Displacementsdialog box. We will set 11 displacements (from 10 000kg through to 20 000kg).




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Click OK to close the dialog box.

4. Now we are ready to run the analysis. To do this choose Analysis | Start

Limiting KG Analysis from the menu, or choose the Start Analysis icon, , on theAnalysis toolbar.

5. To view the results go to the results window, Window | Results from the

menu or click on the Results icon, .

The results show the displacement and corresponding minimum VCG the vessel can

have to comply with the chosen criteria. The criteria which the vessel will first failon is also displayed in the Type column. The results may also be displayed in

graphical format, Window | Graph.




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Tutorial 7: Longitudinal Strength Analysis

The longitudinal strength analysis lets you determine the bending moments and

shear forces created along the length of the hull due to the forces applied from the

loads entered in the Loadcase window and the buoyancy forces. The analysis canbe carried out in flat water or in a waveform.



folder.





2. Choose Longitudinal Strength Analysis from the Analysis toolbar.

3. we now need to set up the loadcase for analysis in the Loadcase window.

Choose Window | Loadcase from the menu. You may notice that the loadcase table

for this analysis is slightly different than for other types of anlysis. There are twoextra columns for defining the fwd. and aft. limits of the longitudinal distribution of

weight for each item. Fill out the loadcase window as shown below (remember to

press the form compartment icon, , to have the tank contents calculated):

4. When a weight is defined in the Loadcase window for LongitudinalStrength Analysis the fwd and aft limits of each weight need to be defined. If it is

not explicitly defined Hydromax will do one of two things. If the item not definedis a tank then Hydromax will automatically determine the weight distribution of the

contents of the tank up to the %full as defined in the Quantity column when theanalysis is run. If the item is anything else then Hydromax will assume the weight

is distributed 100mm either side of the Long. Arm entered for that item. Whenentering a fwd and aft limit for the weight distribution it should be noted that

Hydromax automatically assumes a trapezium for the load distribution. That is, if

the longitudinal arm is entered mid way between the fwd. and the aft limits then the

load will be assumed to be uniformly distributed. However if the load arm enteredis 1/3 the way from the fwd limit to the aft limit then the load will be distributed as




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a triangle from maximum at the fwd. limit to 0 at the aft limit. This means that thelongitudinal arm should always lie within the middle third of the limits if negative

loads are to be avoided.

5. Switch to the Profile view (click on the profile icon, , from the

toolbar). We are now ready to run the analysis. Select Analysis | Start Longitudinal

Strength Analysis from the menu.

6. Open the results graph window (Window | Results from the menu). The

graph should look similar to the figure below:

The weight distribution along the vessel is represented by the black line and thebuoyancy distribution is represented by the red line. The calculated results include

the net load (weight buoyancy), the shear force and bending moment represented

by the green, light green and yellow lines respectively.

7. These results are also represented in numerical form at discrete intervals along

the vessel (at the stations). These may be viewed in the results window(Window | Results), on the Long. strength sheet.




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Tutorial 8: Tank Calibrations

In this tutorial we will calibrate the tanks for capacity, centre of gravity and free

surface moment. The fluid densities and tank permeabilitys may be varied

arbitrarily. Each tank that has been calibrated has a table of tank capacitiesavailable through the Results window, and a separate graph of its volumetric

properties available through the Graph window.



folder.

When prompted, select Read Sections from File and set precision to medium. ClickOK to close the dialog box. If you change to the Design window (select from the

menu either Window | Profile, Window | Plan, Window | Perspective or Window |



2. Choose Tank Calibrations from the Analysis toolbar.

3. Switch to the loadcase window (Window | Loadcase). Select Analysis |

Form Compartments from the menu.

4. Next we want to set up a custom sounding pipe in tank 1. Hydromaxallows sounding pipes to be defined for each tank. One sounding pipe per tank is

permitted and up to 9 vertices per sounding pipe, allowing inclined, bent or curved

sounding pipes to be modelled. Switch to the sounding pipe definition window,Window | Input | Sounding Pipe. Fill the table out as shown below. To add extra

rows use the Ctrl + A keyboard command.

5. To view the sounding pipe you have just created go to the Perspective

window, . The sounding pipe you have just created is shown below (under the

arrow pointer).




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Hydromax creates a default sounding pipe when Analysis | Start Tank Calibrations

is selected. The default sounding pipe is placed at the longitudinal and transverseposition of the lowest point of the tank. If the lowest point of the tank is shared

between several locations (e.g. the bottom of the tank is flat either longitudinally or

transversely) the default sounding pipe location is placed at the aft-most low pointand as close to the centreline as possible. The top of the sounding pipe is taken to be

level with the highest point of the tank and the default sounding pipe is assumed tobe straight and vertical

6. We are now ready to run the tank calibrations. From the menu choose

Analysis | Start Tank Calibrations or click on the start analysis button from the

analysis toolbar, .

7. Results are displayed both in graphical and numerical format. There is one

graph produced for each individual tank. To view results for, say, tank 3 selectWindow | Graphs | Tank 3 from the menu. The numerical results from all of the

tanks are displayed in one table, to view select Window | Results from the menu.

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