apuntes maxsurf

8/17/2019 apuntes maxsurf

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APUNTES DE PROGRAMAS INFORMÁTICOS NAVALES

Profesor: Leandro Ruiz Peñalver

4.9.- Bonding ........................................... 13 INDICE

5 Developable Surfaces......................... 13

6 Advanced Functions............................ 15 1 Introducción 1

6.1.- Transpose........................................ 15 2 Surfaces 1

6.2.- Input of Data.................................... 15 2.1.- Surface Algorithms.............................1

6.3.- Output of Data .................................15 2.2.- Definición de la malla........................2

6.4.- Parametric Transformation .............. 15 3 Using Maxsurf .......................................2

6.5.- Fitting Surfaces to ExistingDesigns. 15 3.1.- Ventanas............................................2

3.2.- Creating Your First Design.................3

3.3.- Setting the Frame of Reference.........4

1 Introducción3.4.- Background Images...........................4

3.5.- Showing the Net.................................5 El objetivo de esta guía es conseguir unaaproximación rápida a la utilización delprograma Maxsurf, siendo esta un resumen delmanual del usuario de MAXSURF.

3.6.- The Control Box .................................5

3.7.- Hydrostatics .......................................6

3.8.- Girth...................................................6 Se entiende que el lector tiene conocimientosprevios de sistemas de CAD.3.9.- Calculate Areas..................................6

3.10.- Calculations Window..........................6

2 Surfaces3.11.- Control Points Window.......................6

3.12.- Markers Window ................................6

2.1.- Surface Algorithms3.13.- Surface Window.................................7 The basis functions are determined by a vectorof knots T where T={t0,...,ti,ti+1,...,tm} andm=number of control points+order of the curve.

3.14.- Surface Assemblies ...........................7

3.15.- Offsets Window..................................7 degree p (order k=p+1) is given by3.16.- Calculating Offsets.............................7

otherwise

t t t if t N

ii

i0

1)(

1

0,

+


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3 Using Maxsurf

3.1.- Ventanas

The drawing windows are titled:

• Plan• Profile

• Body Plan

• Perspective

Other windows exist for the input or display ofdata and may be accessed by selecting theirname from the Windows Menu. The datawindows are titled:

2.2.- Definición de la malla

The net is formed by rows and columns ofcontrol points and has four edges and fourcorners. Up to 25 rows and 25 columns of

control points may be used, depending on thecomplexity of the desired surface. Note that thislimit is for manually defined surfaces, thosesurfaces which have been imported from otherCAD programs (in IGES format) may have anynumber of control points. The surface may havedifferent flexibility in the row and columndirections.

• Calculations

• Control Points

• Markers

• Surfaces

• Offsets

• Curve of Areas

Together with the surface edges you will alsosee some squares joined by light blue lines.These squares are the control points that affectthe surface shape. Four of the control points oneach surface will be painted purple indicating

that they are surface corner points. Across thewindow is a yellow line which is the DatumWaterline (DWL).

At the bottom of the Profile window there arefour position indicators which give the onscreen position of the cursor in real worldcoordinates. The first two indicators show thelongitudinal and vertical location of the cursorand the second pair of indicators show theangle and distance of the cursor from the last

point clicked. The indicators are updated as youmove the cursor. The position indicators are

Guía rápida de Maxsurf 05/05/2003 Pág 2 de 24


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also present in the Body Plan and Planwindows.

3.2.- Creating Your First Design

The control point net is made up of longitudinal

rows and transverse columns. Columns ofcontrol points may be added and deleted in thePlan and Profile views, while rows of controlpoints may be added and deleted in the BodyPlan view.

Type in the following dimensions Añadir una superficie

Value Meters

Length 7.5

Beam 3.6

Depth 0.60 To modify the sheer line plan you should movecontrol points in the Plan window.

• Bring the Plan window to the front by choosing

Plan from the Window menu.OBJETIVO , crear esta embarcación

• Select the top right hand corner points of the

surface.

Use the selection box to do this. In thisselection you have in fact selected two control

points, one being the corner control point andthe other being an intermediate control point inthe right hand edge.

Before you start modelling, you should set upthe units and overall dimensions for yourdesign.

• Choose Size Surfaces from the Surfacesmenu.



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EL perfil

3.4.- Background Images

Maxsurf has no built-in image manipulatingcommands, other than to control the position

and scale of the image.It is also helpful if you make the backgroundcolour of your image similar to that of theMaxsurf background colour, since it will beeasier to see the control points and other lineswhich are Drawn over the top of the image byMaxsurf

3.3.- Setting the Frame of Reference

Primero poner el origen de coordenadas

Many of the dimensioning and calculationfunctions in Maxsurf require you to correctly setup the frame of reference which describes the

location of key points such as baseline,amidships, forward perpendicular and aftperpendicular.

3.4.1.- Importing an Image

File | Import | Import Image Background (note

you must have a design already open).If the image is not visible, check that the displayoption is turned on: Display | Background |Show Image.• Choose Frame of Reference from the Data

menu3.4.2.- Setting the Zero Point

To set the image zero point, select Display |Background | Set Image Zero Point. Then clickthe mouse at the position in the image which isthe design zero point:



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3.4.3.- Setting the Scale

So to set the scale of the background image,select Display | Background | Set Image

Añadir filas

3.5.- Showing the Net

• Use the Contours command from the Displaymenu to turn off the display of sections

• Select Net | Show Net from the Display menuto turn on the net

• Select Half from the Display menu so that onlyone half of the symmetrical design is displayed

Adding a Column

• Select the Plan window from the Windowsmenu.

• Select Add Column from the Controls menu.

• Position the Add cursor at the point where youwish to insert the new column on the sheer lineedge.

3.6.- The Control Box

The control box provides a means of accessingthe transverse columns of control points for thecurrent surface allowing you to modify sectionalshape.

Añadir columnas

Changing the Current Section

Changing the Current Column

• Click to insert the new column.Inserting Control Points Setting Flexibility

Adding a Row



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3.7.- HydrostaticsIn this case we wish to make the design fairer in thelongitudinal direction.

3.8.- Girth• Select Attributes from the Surfaces menu andchoose Default from the sub-menu

3.9.- Calculate Areas

The attributes dialog box for this surface will appear.3.10.- Calculations Window

3.11.- Control Points Window

3.12.- Markers Window

Markers are reference marks displayed on thescreen. They may be offset data that has

originated from an existing hull or simply limitingdimensions that need to be visible whiledeveloping a design.

Removing Control Points

For example, to delete a control point column

from the Profile window:

• Select the Profile window from the Windows

menuEach marker can be associated with a station inyour design. Usually if you are importingmarkers which form the offsets of an existingdesign, you will set up the grid in Maxsurf tomatch the station spacing of the original design,and then set the station number of each markerto match its station in the offsets table.

• Select Delete from the Controls menu.

Markers may also be associated or linked to aspecific surface and location in that surface.Once linked to a surface, the marker takes on



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the colour of that surface. This function may becontrolled with "Use Surface Colour forDrawing Parametrics" control in the View |

Preferences dialog. If this control is turned off,markers which have been linked to a surface

will be displayed in the same colour as surfaceparametrics.

Alternatively, to edit a marker directly

• Double click on a Marker in one of the drawingwindows.

3.15.- Offsets Window

Es la Cartilla de trazado.

Distancia a superficie

The offsets window allows you to calculate andview the offsets for a design on screen. Offsetsare found for the given grid spacing as set inthe Grid Spacing dialog from the Data menu.

3.16.- Calculating Offsets3.13.- Surface Window To calculate offsets

• Select the Offsets window.

• Select Calculate Offsets from the Data menu.

A dialog will appear allowing you to choosewhether or not to include skin thicknessdeduction and/or to automatically create a tableof markers from the calculated offset points.

3.14.- Surface Assemblies



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3.17.- Copying Offsets

Offsets may be copied for transfer to otherprograms. To do this

• Click in the top left hand corner of the Offsetstable.

This selects and highlights all of the Offsetswindow for copying.

• Select Copy from the Edit menu.

3.17.1.- Customizing Offsets

Once a table of Offsets has been calculated inMaxsurf, it is possible to customize the namesused for waterlines, buttocks, diagonals, feature

lines and edges. Simply type the text requiredinto the required cell in the Offsets window.These names will be used when the table ofoffsets is printed or written to a file.

3.17.2.- Writing an Offsets FileIf you have chosen to deduct skin thickness,

Maxsurf will add or deduct that thicknessperpendicular to the surface at each point onthe hull, so that areas of the hull that are notparallel to the centreline will be correctlycalculated.

3.18.- Curve of Areas Window3.19.- Maxsurf Preferences

These may be changed by selectingPreferences from the View menu.



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3.19.1.1.2 Forward Extremity.

The forward most point of all existing surfaces.

3.19.1.1.3 Forward Perpendicular.

This is specified in the Frame of Reference

dialog where it may be automatically positionedat the intersection of the design waterline withthe bow.

3.19.1.1.4 Amidships.

Midway between fore and aft perpendiculars.

3.19.1.1.5 Aft Perpendicular.

This is specified in the Frame of Referencedialog where it may be automatically positionedat the intersection of the design waterline with

the stern.

3.19.1.1.6 Aft Extremity.

The aft most point of all existing surfaces.

3.19.2.- Grid

The positions of the Sections, Waterlines,Buttocks, and Diagonals form what is called theGrid. The grid can be displayed on any windowby selecting the Grid command from the

Display menu.

3.19.1.- Design Frame of Reference

This is used to define the position of the datumwaterline, the forward and aft perpendiculars,the origin for measurements and the position ofsection, waterline, buttock and diagonalcontours.

Elements can be added to the Grid by using theGrid Spacing function from the Data menu.

The positions of Grid elements are as follows:

Sections3.19.1.1.- Frame of Reference

ButtocksThe Frame of Reference dialog is used tospecify the positions of the key locations usedin ship design. These positions are:

Waterlines

Diagonals• Forward Perpendicular

3.19.3.- Contours• Aft PerpendicularThe Contours option allows you to select whichcontours are drawn on the screen at any giventime. Any combination of contours may bechosen from the contours dialog.

• Amidships

• Datum Waterline (DWL)

• Baseline

3.19.1.1.1 Zero Point

The zero point is the reference point that allmeasurements are taken from. You maychoose the position of the longitudinal zero

coordinate by selecting from the availableoptions:



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4 Manejo de superficies

4.1.- Surface Flexibility

4.2.- Surface Appearance

4.3.- Surface Properties

4.6.- Surface Operations

4.6.1.- Adding Shapes

4.4.- Surface Precision

Each curve drawn by Maxsurf is made up of anumber of short straight lines. The number ofcurve segments apply both to lines drawn to thescreen, Clipboard, and IGES files, as well as tooutput devices such as printers.

4.5.- Surface Curvature.Render may only be selected when thePerspective window is active.



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4.6.5.- Moving Surfaces

4.6.6.- Size Surfaces

4.6.7.- Flipping Surfaces

Surfaces may be flipped about specified planes:longitudinally, transversely or vertically.

4.6.8.- Rotating SurfacesPàg. 90

4.6.9.- Aligning SurfacesPàg. 91

4.6.10.- Trimming Surfaces

A surface which has invisible regions is said tobe trimmed.

Maxsurf uses the concept of a 'region' to definean area of a surface that may be visible orinvisible (trimmed off). These regions aredefined by the boundaries of the surface andany intersections that the surface has with anyother surfaces.

4.6.2.- Adding Surfaces

Adding Surfaces Pág. 85Initially, all of the regions on the surface arevisible and selected. We need to de-select theregions which need to be trimmed off.

4.6.3.- Deleting SurfacesTo change the visibility of a region, click insidethat region. The shading will be turned off or on

as appropriate to show whether it is selected ornot.

Pàg. 86

4.6.4.- Duplicating SurfacesPàg. 86

Displaying Trimmed Surfaces



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4.7.4.- Display of Control Points

4.7.4.1.- Masking the Net

4.7.4.2.- it is sometimes very helpful to

be able to select a particular group ofcontrol points to remain visible while theremainder of the net is hidden. This is thefunction of the Mask command.

4.7.4.3.- By selecting all the points onone or two columns and then selectingMask, only the portion of the net selected,and the area of the surface that it exerts aninfluence on, will be displayed.

4.7.5.- Manipulating Groups ofControl Points4.6.11.- Untrim Surface

4.8.- Smoothing and Straighteningrows or columns4.7.- Control Points

Any complete or partial row or column of controlpoints can be straightened into a straight line,or faired into a smooth curve.

4.7.1.- Adding Control Points

To add a control point row or column

• Select the Plan, Profile or Body Plan window, as

appropriate. • Click on the control point at one end of the

group to be straightened.Deleting Control Points

This control point will be the control point at oneend of the selection to be smoothed orstraightened. If after selecting one point youwish to change your selection, simply clickanywhere in the background of the window.

To delete a control point row or column

• Select the Plan, Profile or Body Plan window as

appropriate.

Control point rows may be deleted in the BodyPlan; control point columns may be deleted inthe Plan or Profile windows.

• Hold down the shift key.

• Click on the control point at the other end of the

group.• Select Delete from the Controls menu.

This control point will be the control point at the

other end of the selection to be smoothed orstraightened. It should lie in the same row orcolumn as the first selected control point. If youwish to change your selection after selecting asecond point, release the shift button and startagain with the first point.

4.7.2.- Moving Control Points

Control points may be moved, eitherindividually, or as a group.

4.7.3.- Constraining Movement

Any group or individual control point may beconstrained in its movement by holding downthe Shift key while dragging the control points.The constraint restricts movement to thevertical or horizontal directions. If you releasethe shift key, you are returned to unconstrained

movement.

• To fair the control points, select Smooth

Controls from the Controls menu and select the

desired flexibility.

The stiffer the smoothing, the straighter the line

will become. Smoothing is done in threedimensions.



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• Select Align to vector; end points are movedto closest corresponding points on the vector.

• or to straighten the control points, select

Straighten Controls from the Controls menu and

select whether you wish to straighten in 2D or 3D.4.8.5.- Resizing Control

If you straighten in 2D, the control points will beforced to a straight line in the current view

direction, leaving the third direction unchanged.This can be particularly useful for producingstraight bow profiles or transoms; this is doneby using the Straighten in 2D command in theprofile view. Straighten in 3D will produce astraight line in all three dimensions.

This command may be used to enlarge or

reduce an area of a surface.

4.8.6.- Rotating Control Points

4.8.7.- Compacting Control Points

The Compact function is used when you wish toposition one or more control points preciselyover an existing control point.4.8.1.- Smoothing or Straightening a

Patch

4.8.8.- Grouping Control Points

4.9.- Bonding 4.8.2.- Moving Control Points

Maxsurf allows you to join two surfacestogether along a common edge so that the twosurfaces behave as one larger surface. Thisprocedure is referred to as Bonding. The edgesmay be in the same surface, or in separatesurfaces.

4.8.3.- Resizing Control Points

This command may be used to enlarge orreduce an area of a surface.

4.8.4.- Aligning Control P

Two rules govern which edges may be bondedtogether:

To use Align to Vector:

• Select two control points with the shift key held

down. 1. The two edges that are to be bonded mustshare the samenumber of control points along

their respective edges.• While still holding down the shift key, select one

or more additional points.2. The two edges must share the sameflexibility.

• Select the Align to Vector command.

The first two selected control points define thevector; all subsequently selected points aremoved to the point on that vector closest totheir original position:

4.9.1.- Bonding within a Surface

Edges within a surface may also be bonded toone another as long as they follow therequirements of number of control points andflexibility.

• Before aligning endpoints with vector defined

by two middle points

5 Developable Surfaces• With shift key held down, select two middlepoints to define vector A developable surface is one which can be

formed from a flat sheet without stretching the



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material. This material may be aluminium, steel,wood or even paper - the material chosen hasno effect on whether or not the surface isdevelopable.

Maxsurf does not automatically create adevelopable B-spline surface - it generates

ruling lines which are used as guides to allowyou to see where the developable surface willlie.

Examples of simple developable surfaces are

cylinders and cones, whereas a sphere isclearly not developable.

A developable surface is created from theedges of a B-spline surface and a set of offsetpoints are generated at each station. Theseoffsets are used to manually fit the B-splinesurface to the developable shape. This allowsyou to create a surface that is developablewithin practical tolerances.

The example described below uses the chinehull design, workboat.msd, which may be foundin the \ProgramFiles\Maxsurf\Sample Designs\Workboats\ directory. However, it is necessaryto delete the middle row of control points in theTOPSIDES surface so that it only has controlpoint rows along its longitudinal edges.

When the rulings are viewed in the Body Planwindow, small indicator points are displayedwhere each ruling intersects a section.

You will see a discrepancy between the solidsection line from the existing B-spline surfaceand the indicator points from the developablesurface - this shows you how much the B-spline

surface will need to be distorted to make itdevelopable.

The first step is to design a hull using normal B-spline surfaces that have no intermediate rows -in other words having control points only alongthe longitudinal edges. These edges should be

made as fair as possible and should have theminimum of inflections. You should also set upa set of stations in the Grid dialog. Once youare generally happy with the hull form

In other words, the indicator points are wherethe developable surface (between the twolongitudinal edges) lies. The solid lines are• Select the Surface Attributes for the surface

you wish to be developable. where the B-spline surface actually lies. Yourtask, as the designer, is to add intermediaterows of control points to the B-spline surface so

• Select Developable under Surface Type.

This will display rulings on the hull shape andthe aim should be to get these rulings asregular as possible.

that you can make the B-spline surface matchthe developable surface to within acceptabletolerances.

These points allow you to see what shape thesections of your hull will have. The higher theprecision you are using, the more rulings therewill be and the more points will be shown ateach station. If a station has very few or nopoints displayed, it is usually because thesection at that point is nearly straight and fewrulings intersect the station. You can increasethe number of rulings by increasing the surface

precision.


If all sections are displayed using the contoursdialog, all sections will be marked on the


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rulings. If only one section is displayed, only thecorresponding intersections of that section withthe rulings will be visible. Remember that thecurrent section isselected using the stationindicators in the inset box in the Body Plan

window. When Maxsurf displays the rulings ona hull surface, it displays the final valid ruling, orend ruling, at each end of the surface in blue

6.3.- Output of Data

Maxsurf can output your design lines in a widevariety of file formats and hard copy. Fileformats available are 2D IGES, 3D IGES, 2DDXF, 3D DXF, 3DMF and VRML.

6.4.- Parametric Transformation

The parameters that can be specified aredivided into two groups,(markers colour), while normal rulings are in

yellow (datum waterline colour). If you wish toget the ends of the surface straight (for exampleyou may wish the surface to bond to a straightedged bow cone), you should move the controlpoints on the edges to get the end ruling asparallel to the end of the surface as possible.This will occur when the tangents to the ends ofthe two edge curves lie in the same plane.

Search Parameters and Constraints

.

6.4.1.1.- Search Parameters .

Are those that require a non-linear

transformation of the hull shape. These arePrismatic, Block, and Midship Area Coefficientsas well as the LCB% and LCF%. To vary thesevalues, some form of non-linear transformationof the hull must take place.

If the rulings cross through the end of thesurface, then the end of the developablesurface will not be straight (Remember that therulings are straight lines in the developablesurface.)

6.4.1.2.- Constraints6 Advanced Functions

Are those parameters that can be calculateddirectly using a linear scaling of the hull, namelyDisplacement, Waterline Length, Waterline

Beam and Draft.

6.1.- Transpose

This can be particularly useful if you haveimported a NURB surface which uses adifferent control point orientation from Maxsurfor if you have rotated a surface and the columnselection in the Body Plan view selects columnswhich are now closer to being longitudinal thantransverse.

6.4.1.3.- Comparisons

For comparison purposes it is possible toduplicate the surface prior to modification (theduplicate surface can be made to lie exactly on

top of the original by specifying zero for all threespacings).6.2.- Input of Data

6.2.1.- Importing DXF Markers

6.2.1.1.- Pasting

You can paste data from any spreadsheet,word processor or text editor into the tables inMaxsurf.

6.2.1.2.- Importing IGES Surfaces

6.5.- Fitting Surfaces toExistingDesigns.

Maxsurf will read any NURB surface entities(IGES entity type 128) from the file. Note that atthis stage it will ignore any trimming information

associated with the surfaces i.e. only thecomplete untrimmed surface will be imported. All other data types in the file will be ignored.

Maxsurf has some extremely powerful built in

tools for fitting surfaces to existing marker data.


This version adds a new surface fitting functionto Maxsurf. This function differs from Prefit in


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3. The resulting control point net tends to beregular and smooth with even spacing of rowsand columns that tend to be orthogonal to oneanother.

that it uses a Genetic Algorithm to optimiseboth the surface fit and net fairness, resulting inbetter quality control point nets.

6.5.1.- Surface Fitting with Genetic

Algorithms 4. The resulting surface tends to be fair as well

as fitting the data points closely Although slow, GAs are excellent for solvingproblems with large numbers of dimensions andconstraints. The surface fitting problem falls into

6.5.2.1.- Markers

6.5.3.- Initial Surfacethis category, as it is not sufficient to simplycreate a surface that is a close fit to the datapoints provided, it is also desirable that thesurface be fair and that the control point net besmooth and regular.

The Genetic Algorithm will use the initialsurface as a starting point, so the closer it is toits final configuration the better. It is notessential to get it near to the data points as longas the overall layout of the net is regular.

6.5.2.- Advantages Over Prefit 6.5.3.1.- Fit Surface to MarkersCommand

Prefit is already capable of quickly fitting asimple surface to a table of offsets, however ithas several disadvantages. Once the markers and the initial surface have

been created it is time to fit a new surface.Selecting the Fit To Markers Command fromthe Data Menu brings up the following dialogbox.

1. Ordered data points. Prefit requires that datapoints be ordered in consecutive columns fromthe stern to the bow. Points within

each column should be in the correct order.6.5.3.2.- Licensing of Fit Surface toMarkers command2. Density of data points. Prefit has problems if

the data points are unevenly distributed overthe surface. Please note that the Markers | Fit Surface toMarkers command is only available if you own a

licensed copy of Prefit.3. Poor net of control points. The resulting net ofcontrol points from the Prefit fitting process isoften not suitable for modification in normaldesign work. Columns and rows may beskewed and be irregular in their layout.

6.5.3.3.- Assisted Manual Fit to Markers

Snap Control Point to Marker

Fit Edge to Markers

4. Poor fairness. Even when the Prefit surfacefits the data closely it is possible for it to containsignificant unfairness.

Smooth Surface Interior

Measure Surface Errors

Procedure for Assisted Manual Fitting to Markers

Although much slower, the Genetic Algorithmfitting method has several advantages overPrefit.

PRÁCTICAS CON MAXSURF.

Se parte de unas formas iniciales en Rhinoceros“Superfices_mio.3dm”

1. Data may be unordered. It is not necessaryto organise data into rows or columns, nor is itnecessary for points to be sorted into aparticular order. The GA fitting method canhandle randomly ordered data with noproblems.

En Maxsurf Open New Design

EnData-> poner Units

2. Data may be of varying density with more

points concentrated in areas of greatercurvature or detail.



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En Data->Zero Point

En Rhino seleccionar lo indicado



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Ensure that you have used the Outside Arrowscommand to tell Maxsurf which direction pointsoutwards for each surface.

Analysis with Hydromax is a five-step process.

1. Open the Maxsurf design you wish toanalyse.

Ensure that all surface intersections andtrimming are correct.

2. Choose the type of analysis you wish toperform. The options are:

If skin thickness is to be used in hydrostaticscalculations, ensure that the thickness andprojection direction have been specified for thehull shell surfaces.

a) Upright hydrostatics

b) Large angle stability

c) Equilibrium analysis

d) Specified ConditionVerify that all internal surfaces which are to beused as tank /compartment boundaries aredefined as Internal Structure.

e) KN values and cross curves of stability

f) Limiting KG analysis

g) Tank Calibrations

h) Longitudinal StrengthOpening a Design

When a file is opened a dialog box is displayedallowing

3. Set up the analysis conditions you wish touse. These are Frame of Reference

• Type of Fluid simulation

• Fluid Densities

• Wave conditions if required

• Grounding if required

• Tank and Compartment definitions, whererequired

• Damage condition, if required

• Stability criteria if required

4. Set up the specific Initial Conditions for theanalysis you have chosen. These are:

• Trim – fixed or free.

• Loadcase condition (Displacement and C.G.position) for equilibrium condition and largeangle stability.

If you are reopening an existing Hydromax file,you will be given the option of Reading thesections from the file or Calculate sections. Ifyou are opening a Maxsurf design file for thefirst time, you will only be able to Calculatesections.

• A range of drafts for upright hydrostatics.

• Multiple heel angles for KN calculations andlarge angle stability.

• A range of displacements for KN calculations.• Specific conditions for the SpecifiedConditions Analysis.

Analysis



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• Arrange of displacements for limiting KG Analysis For KN analysis the initial LCG is fixed to the

LCB position in the intact, upright, zero trimcase for each of the specified5. Run the analysis cycle.

displacements. When the vessel is heeled, itmay be fixed or free to trim.Choosing Analysis Type

Displacement and Heel are varied in fixedsteps. Output is in the form of a table of KNvalues and a graph of Cross curves of stability.

When performing the first five analysis types,there are three pairs of related variables thatare used :

Limiting KG AnalysisDraft & Displacement

Trim & Longitudinal Centre of Gravity (LCG)

The Limiting KG analysis may be used to obtain

the highest vertical position of the centre ofgravity

Heel & Transverse Centre of Gravity (TCG)

Upright HydrostaticsHydromax runs several large angle stabilityanalyses at different KGs. The selected stabilitycriteria are evaluated; the centre of gravity isincreased until one of the criteria fails.

For Upright Hydrostatics, Heel and Trim arefixed and Draft is varied in fixed steps.Displacement and Centre of Buoyancy andother hydrostatic data are calculated during theanalysis.

Longitudinal Strength

The output from the longitudinal strengthcalculations is a graph of weight, buoyancy, netload, shear force and bending moment alongthe length of the hull.

Large Angle Stability

For the Analysis of Large Angle Stability,Displacement and Centre of Gravity arespecified in the loadcase. Trim may be fixed, orleft free to find its equilibrium position. Heel isspecified in fixed steps.

Tank Calibrations

Tanks can be defined and calibrated forcapacity, centre of gravity and free surfacemoment. Fluid densities and tank permeabilitiescan be varied arbitrarily.

Equilibrium Condition

Equilibrium Analysis requires that Displacementand Centre of Gravity are fixed. Hydromaxiterates to find the Draft, Heel Angle and Trim Angle that satisfy equilibrium.

Tank calibrations are for the upright (zero heel)vessel, but the vessel's trim may be specified.

Hydromax Limitations Specified ConditionIn this analysis mode, any combination of inputvariable pairs may be specified.

Hull Shapes Hydromax works by applying trapezoidalintegration to data calculated from a series ofKN Values



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cross sections taken through the hull surfaces.Where a hull consists of an open shell (e.g. ahull surface with no deck), Hydromax willautomatically close the section off with astraight line.

This is not an acceptable shape.

Esta sección se puede entender como

Hydromax will generally have no problemcorrectly interpreting your design as long asthese restrictions are observed :

Internal Structure

The same rules apply for groups of surfacesused to define internal structural which have

been selected to form a tank or compartmentboundary.

Setting Initial Conditions Coordinate System

Hydromax uses the following coordinatesystem:

Frame of Reference and Zero Point

Trim

Density

Where necessary, the specific gravity of sea

water (the fluid in which the vessel is floating)and fluids commonly carried on board can beadjusted using the Density dialog.

Wave Definition

The water plane can be specified as flat, or as asinusoidal or trochoidal waveform.

Grounding

It is possible to specify grounding on one or twopoints of variable length.

Hog and Sag

Hog or sag is distributed in a parabolic curvecentred at either the amidships location or aspecified longitudinal position relative to thezero point.

Loadcase

For the calculation of Large Angle Stability,Equilibrium and Longitudinal Strength analyses,Hydromax requires you to set up the

displacement and centre of gravity informationusing a spreadsheet displayed in the Loadcasewindow.

Compartment Definition

By entering data in the columns of the table,you can define a boundary box for thecompartment and modify the compartment 'sname, permeability and, in the case of a tank,the specific gravity of the contents.

Adding Simple Tanks


Simple tanks and compartments are created byspecifying six values that define a box-shaped


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boundary for the tank. These values are thefore and aft extremities of the tank, the top andbottom, and the port and starboard limits of thetank.

Creating Tapered Tanks

The column headings in the CompartmentDefinition window include terms such as 'FBottom, 'A Top', 'F Port' and 'A Starboard'. The'F' and 'A' abbreviations stand for Forward and Aft, in other words the two ends of thecompartment. You will notice that aft columnscontain the word "ditto". This means that thevalue is identical at the aft end of the tank to theforward end, resulting in a parallel tank.

Linked Tanks and Compartments

Adding Complex Tanks Using Surfaces

Forming Compartments

Once the boundary box of the tank has beendefined it can be intersected with the hull tocreate the tank shape. This is done either byselecting Form Compartments from the Analysis menu or completing a Tank Calibration

analysis.

Modelling Non- Buoyant Areas

Non-buoyant areas of the hull can normally bemodelled with hull surfaces. However, there areoccasions when it is mode convenient to usenon-buoyant volumes. These are permanentlyflooded compartments.

PermeabilityTanks may have two permeabilities, one whichis used when the tank is intact and the otherwhen it is damaged.

Specific Gravity of Tank Fluids

Fluid Análisis Method

Hydromax allows you to specify two differentways of analysing any fluids contained in tanksor compartments.

• Use corrected VCG - Tank capacities and freesurface moments are calculated for the uprighthull (zero trim and zero heel). The effective rise

in VCG due to the tanks' free surface iscalculated by summing the maximum freesurface moment of all the tanks filled less than98% capacity and dividing by the total vesseldisplacement.

• Simulate fluid movement - This method is afaithful simulation of the movement of thecentre of gravity of the fluid in each tank. Everytank is rotated to the heel and trim angle beinganalysed.

Damage Definition

Hydromax is capable of including damage to ahull shape in all the analysis modes. Hydromax

allows you to set up a number of DamageCases.

Other Initial Condition Data

Other initial condition data may be defined. Thisincludes down

flooding points, margin line and modulus points.The two former are used when evaluatingcriteria. See Reference section for furtherdetails.

Stability Criteria

IMO

IMO Code on Intact Stability for All Types ofShips Covered by IMO Instruments: Resolution A.749 (18). IMO publication IMO-874E; Chapter3.

HSC Monohull

IMO International Code of Safety for High-Speed Craft: Resolution MSC.36 (63). IMOpublication IMO-187E; Chapter 2.

HSC Multihull

IMO International Code of Safety for High-Speed Craft: Resolution MSC.36 (63). IMOpublication IMO-187E; Chapter 2, Annex 7.

MARPOL

US Navy

DDS 079-1: Stability and Buoyancy of U.S.Naval Surface Ships

USL – Uniform Shipping Laws Code (AustralianTransport Council)Heeling Arms



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Additional heeling curves superimposed on GZcurve. Arbitrary positive powers of Cos(heel)are allowed.

Initial Conditions

The initial conditions required for Equilibrium analysis are:

• Frame Of Reference from the Display menu (essential)Specifying and Selecting Criteria

• Error Values from the Edit menuTo select particular criteria, click on the check boxes on the left

side of the dialog box. To modify criteria, click in the text boxand enter the required value.

• Fluid simulation type from the Analysis menu

• Density from the Analysis menu

Upright Hydrostatics • Wave Form (if any) from the Analysis menu• Damage (or Intact) from the Analysis toolbar

Initial Conditions • Grounding (if any) from the Analysis menu

The initial conditions required for Upright Hydrostatics are:• Displacement and Centre of Gravity using the Loadcasewindow• Frame Of Reference from the Display menu (essential)

• Density from the Analysis menuSpecified Conditions

• Wave Form (if any) from the Analysis menuSpecified Condition analysis lets you determine the hydrostatic

• Damage (or Intact) from the Analysis toolbar parameters and equilibrium response of the hull as a result of

• Trim from the Analysis menu, you may specify a fixed trimfor all drafts changing the heel, trim and immersion.

Initial Conditions • Draft from the Analysis menu specify range of drafts foranalysis

The initial conditions required for Specified Condition analysisare:Setting a Range of Drafts

A range of drafts for upright hydrostatic calculations can bespecified using the Drafts command from the Analysis menu.

• Frame Of Reference from the Display menu (essential)


Large Angle Stability • Wave Form (if any) from the Analysis menu

• Damage (or Intact) from the Analysis toolbarInitial Conditions • Specified Conditions from the Analysis menuThe initial conditions required for large angle stability are:

KN Calculations • Frame Of Reference from the Display menu (essential)• Error Values from the Edit menu

Initial Conditions • Fluid simulation type from the Analysis menu

The initial conditions required for KN calculations are:• Density from the Analysis menu

• Frame Of Reference from the Display menu (essential)• Wave Form (if any) from the Analysis menu

• Fluid simulation type from the Analysis menu• Damage (or Intact) from the Analysis toolbar

• Density from the Analysis menu• Stability Criteria from the Analysis menu

• Wave Form (if any) from the Analysis menu• Trim (fixed or free) from the Analysis menu

• Damage (or Intact) from the Analysis toolbar• Displacement and Centre of Gravity using the Loadcasewindow

• Trim (fixed or free) from the Analysis menu

• Displacement from the Analysis menu, select range foranalysis

• Heel from the Analysis menu, select range for analysis

Setting Heel Angles• Heel from the Analysis menu, select range for analysis

A range of heel angles for large angle stability calculations can be specified using the Heel command from the Analysis menu.

Setting a Range of Displacements

A range of displacements for KN calculations can be specifiedusing the Displacement command from the Analysis menu.Equilibrium Analysis

Limiting KG Equilibrium analysis lets you determine the draft, heel and trimof the hull as a result of the loads applied in the table in theLoad window. The analysis can be carried out in flat water or

in a waveform.Initial Conditions



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The initial conditions required for Limiting KG analysis are:


• Fluid simulation type from the Analysis menu


• Wave Form (if any) from the Analysis menu• Damage (or Intact) from the Analysis toolbar

• Trim (fixed or free) from the Analysis menu

• Criteria from the Analysis menu, select which criteria should

be

evaluated

• Displacement from the Analysis menu, select range foranalysis

• Heel from the Analysis menu, select range for analysis

Longitudinal Strength Initial Conditions

The initial conditions required for Longitudinal Strengthanalysis

are:


• Fluids simulation type from the Analysis menu


• Wave Form (if any) from the Analysis menu

• Damage (or Intact) from the Analysis toolbar

• Grounding (if any) from the Analysis menu

• Displacement and Centre of Gravity using the Loadcasewindow

Allowable Shears and Moments

The Modulus window can be used to enter maximum allowable

shears and moments.

Tank Calibrations

Initial Conditions

• Trim from the Analysis menu, you may specify a fixed trimfor all

drafts

• Tank definitions, permeability and contents, see below:

Compartment

Tank boundaries and the properties of the tank contents. This is

done using the Compartment Definition window.

Defining Tank Properties

Starting and Stopping Analyses

To start the analysis, choose Start Analysis from the Analysismenu or toolbar.

Calculations may be interrupted at any time by hitting theEscape key.

Data Transfer A wide range of options for transferring data from Hydromaxto other programs such as spreadsheets and word processors is

provided.

Saving Results to

a File

Saving the Design

Saving Loadcases To a File

Saving Damage Cases To a File

Saving Compartment Definitions To a File

Copying Data

Copying Hull Views

Copying Graphs

Documents

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