Advanced Tutorial Topics

How to Create Computing MultiSurf Models

Variables, Formulas and Functions
by Reinhard Siegel

Introduction

There are two ways to specify a real number in the definition of an object: with a constant value or a real entity. Variables and Formulas are example of real entities. A Variable carries a value that lies within a specified range. A Formula involves an expression made of real entities, constants, operators and Func-tions. Variables and Formulas can be parents of all objects depending on a real value.
What are the advantages of Variables and Formulas?
With Variables and Formulas simpler, clearer models can be created. Models can be changed immediate-ly, you do not have to search for the point that controls a certain part of the construction, one can directly select the variable in the Entities manager and then change its value. Example I-beam: for the given basic geometry just 4 measurements determine the shape. Using Variables and Formulas the coordinates of necessary auxiliary points do not need be individually constructed, their coordinates can be determined by calculation.
Variables and Formulas can be used to create models that carry out calculations: main dimensions, area sizes and center of gravity, rating rule measurements, floating position, hydrostatic characteristics, hydro-dynamic resistance and so on. In this way, a model can provide additional information to the designer about itself, always updated immediately upon a change of model shape.
Variables and formulas expand the functionality of MultiSurf enormously. MultiSurf is limitless.

Decks and Superstructures

On decks, trunk cabins and bubbles
by Reinhard Siegel

Introduction

Small boats have no deck or cabin, but those are indispensable parts of larger vessels. This article describes various methods to model surfaces for decks and superstructures in MultiSurf.

Fitting Surfaces to Predefined Shapes

How to create a MultiSurf model from a paper lines plan

by Reinhard Siegel

Introduction

When you create a new design from scratch, you have complete freedom to shape the surfaces, and when all looks pretty and satisfies the design parameters you can quit. This is “freeform design”. But if the objective is to reproduce a predefined shape it comes to “surface fitting”. The freedom to shape is re-placed by the challenge to create a geometry which is close to the given data as well as being fair. In this article we will discuss the required steps how to safely overcome this exercise in MultiSurf. (Click on the image for the full document)

 

hull_from_paper

 

On the rounding of bows, sterns, sharp waterlines and on the attachment of keels

How to make a B-spline Lofted Surface touch another surface

by Reinhard Siegel

Introduction

There are many situations in the modeling of the geometry of hulls and superstructures, where a basis surface requires some rounding. Being small in proportion there are no sophisticated freeform requirements, except to look nice and touch adjacent surfaces smoothly.

This article shows methods how to employ the surface type B-Spline Lofted Surface for a fair attachment of classic hull keels, to round the bow or the stern of a hull, to remove sharp waterline entries. Its aim is to explain the pros and cons of various procedures, so in the end you can decide which method will suit your needs best.

bowround

 

On Modeling Classic Sailing Yacht Hulls

Some variations of the round bilged hull theme

by Reinhard Siegel

 Introduction

The hull shape of a classic sailing yacht is more complex than the hull of a modern sailing boat: long bow and stern overhang, full, easily turned garboards, rudder attached to keel trailing edge as a flat piece or being part of the keel surface as a flap. Boats of the Dragon class, meter class yachts or traditional long keel sailing cruisers are examples of the hull type in question.

This article has in view to show methods how to create classic yacht hull forms in MultiSurf. It is not about designing a hull with specific dimensions and shape, but explains the pros and cons of various procedures, so in the end you can decide which method will suit your needs best.

classic

Modeling a Rudder in MultiSurf

Strategies and methods

by Reinhard Siegel

Introduction

This article presents several methods how to create a rudder. It is not about designing a rudder of specific dimensions and shape, but shows what methods are available and which strategy is practical for your purpose.

Modeling Round Bilge Hulls

C-Spline Lofted Surface and the vertex curve method

by Reinhard Siegel

Introduction

This article shows on the basis of the model sy15.ms2 by what considerations the author creates a round bilge hull in MultiSurf. This is not about making a hull with specific dimensions or shape features. But it comes to show which method is practical, so in the end it is on the screen what you imagine.

 

Round Bilge Hull With Full Length Chine

A simple variation of the round bilge hull theme

by Reinhard Siegel

Introduction

Modern racing yachts feature a single longitudinal chine. On some boats it runs from stem to stern, on others it is of partial length. According to the motto: what is right for a racer cannot be wrong for a cruiser, there are more and more boats with this hull form characteristic.
On the basis of the model sy15_full_chine.ms2, this article shows how to create a hull with a full length chine in MultiSurf. This is not about making a hull with specific dimensions, but shows which method is practical, so in the end you achieve what you intend.

Round Bilge Hull With Vanishing Chine

A complex variation of the round bilge hull theme

by Reinhard Siegel

Introduction

Modern racing yachts feature a single longitudinal chine. On some boats the chine runs full length from stem to stern, on others it starts at the stern, but vanishes somewhere forward of the middle of the hull.

In this article I would like to explain on the basis of the model sy15_vanish_chine.ms2 how to create in MultiSurf a round bilge hull with a partial length chine, which proceeds from the stern. This is not about making a hull with specific dimensions, but shows which method is practical, so in the end you achieve what you imagine.

Vanishing Spraychine
On Hullform Characteristics

by Reinhard Siegel

Vanishing spraychine

Introduction

Some boat hulls feature a partial length spraychine in their forebody topside surface. This form characteristic is closely related to the partial length chine. There is not just a break but a real step in the run of transverse cross sections. Beyond begin and end of the vanishing spraychine the hull surface is smooth and free of breaks.

On Modeling Ship Hull Forms in MultiSurf

by Reinhard Siegel

Introduction

An evident form characteristic of ships, such like cargo vessels, container carriers or cruise liners is, that portions of the hull surface are flat. Many ships also feature a parallel midbody, i. e. a sequence of cross sections is identical. Common to ships is also the bulbous bow. This article deals with methods how to model those hull forms. It is not about designing a hull with specific dimensions and shape, but explains the pros and cons of various methods.

The Use of Components for the Modeling of 2D Structural Parts in Hull Construction

On the creation of a frame in the aftbody of a metal powerboat

by Reinhard Siegel

Introduction

Let us assume we have made the geometry of a standard metal powerboat: surfaces for hull and deck. And we went beyond this ordinary extent and have also added a series of longitudinal frames (stiffeners) to support topside, bottom and deck. Next we would export sections and continue in a cad program in order to define all the flat structural parts required for the construction of the boat. But this means: the world of relational geometry is left. If there will be any change of the model, the cad drawings must be adapted. And certainly, there will be changes. In the following it is shown by the example of a transverse frame, that there is no need to leave MultiSurf for the creation of complex flat parts.

Chine-Form Powerboat Hulls

A further variation of the C-spline Lofted Surface theme

by Reinhard Siegel

Introduction

Powerboats show more complex hull shapes then sailing boats. Chines, steps in the topside, tunnels in the bottom, transverse bottom steps, to name a few geometry form properties.

In this article I would like to explain on the basis of the model pb10.ms2 how to create in MultiSurf a standard chine form hull for powerboats. This is not about making a hull with specific dimensions, but shows how the C-spline Lofted Surface can also be used advantageously for this kind of hull shapes.