Article written by Gerard Petersen a Naval Architect who uses Rhino extensively for developing new ship concepts at ScheepsbouwKunst .
As the initiator of Rhinocentre.nl , which is a centre of excellence for Rhino users, Petersen visits a lot of design bureaus and shipyards to advice and train people in using Rhino.
Rhinoceros is already used a lot in the Marine Industry. Not everybody is aware of the marine design capabilities of Rhino as a lot of users only apply Rhino in superstructure design or visualisation purposes by importing geometry in Rhino from other Cad tools.
If the tools are there, you can design directly in Rhino and see how far you can get in the process up to production.
This article offers an overview of experiences and knowledge when using Rhino for Hull Modeling and Naval Architecture. The hull modeling is only a part of the total Naval Architecture process, therefore specific Naval Architecture aspects are also evaluated.
Please send me your comments, questions and experiences.
Content
- Rapid Hull Modeling Methodology
- Rhinomarine Hull Design & Fairing Module
- Direct Control Point Manipulation
- T-splines modeling
- Extra Modeling tools
- Extra Naval Architecture tools
- Conclusions
Note
Understanding the basic rules of fairing is essential for every method of hull generation. Download and read the Rapid Hull Modeling Methodology tutorial which also explains some basic rules.
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Rapid Hull Modeling
en.wiki.mcneel.com/content/upload/images/Rhinohull1.gif
This method is based on the creation of a few mastercurves which describe the stem, stern, mainframe etc.
Advantages:
• Easy to transform later (especially with ‘record history’ in Rhino 4)
• Fair single surface hull
• Fast generation of new concepts
• High quality bulbous bow and parallel midship section
• Free
• Posibility to parametrize the design with scripts
Disadvantages:
• Singularities are possible when two or more control points of the surface are at the same position
• Local transformations only possible by changing curve control points
Go to www.rhinocentre.nl to download a .3dm example file plus a small PDF manual about fairing and using the method.
Go to the Rapid Hull Modeling wiki page to write down your comments, experiences and questions.
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Rhinomarine Hull Design & Fairing Module
Proteus Engineering offers marine plug-ins for Rhinoceros. You can buy 4 modules which add functionality to Rhino:
1- The most important one is the hydrostatics and stability module to be able to calculate the stability curve of your design. This module also offers a sectioning tool to be able to create sections, buttocks, waterlines etc. with a simple menu.
2- The Hull Design & Fairing module uses wizards to generate sailboat monohull designs and planing hull designs. The Rhinomarine method creates directly a single surface describing the hull. Furthermore extra functionality is added to help you manipulating control points of the surface, update sections automatically and create automatically a linesplan.
3- A Performance module makes it possible to estimate the resistance of planing vessels with the Savitsky method.
4- The Model Management Module is meant to handle complex models containing a lot of objects. It is also possible to add weight and cost properties to the objects for calculation purposes.
Focusing on hull modeling, the Hull Design & Fairing module offers functions for:
- Converting the viewports to marine standard views and coordinate system.
- Defining sections, buttocks, waterplanes etc.
- Updating these intersections automatically in real-time as the surface is modified
- Generating a linesplan
- Control point manipulation to change the shape of any surface
- Adding control points
- Evaluating fairness of curves
- Hull wizard for quickly creating hull surfaces from input of dimensions and shape factors (currently limited to chine hulls and sailboat hull)
Advantages for hull modeling:
• Easy to use toolbox for creating and modifying any type of hull or surface.
• High quality single surface
• Flexibility to change the design later due to wizard
• Extra functionality to easily create sections/ waterlines and buttocks
• Little chance for singularities
Disadvantages for hull modeling:
• Hull wizards limited to two shiptypes (possibility to change wizard based surfaces with direct control point manipulation), although the other functionality can be used to create and modify any type of hull or surface
Read more or download an evaluation version at www.rhinomarine3d.com
You can also view some instructional video's at the Rhinomarine website.
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Direct Control Point Manipulation
Experienced users can design hull forms with direct control point manipulation. This method is based on generating a single surface with rows and columns of control points. Start with a flat plate and sculpt the form by dragging and pulling control points.
Advantages
• High quality single surface possible (depending on skills of user)
• A lot of control to adjust the surface
• Every imaginable surface is possible
Disadavantages
• Control points have to be positioned in a grid of rows and columns. Therefore too many control points at places where little control is needed and often less control points at places where a lot of control is needed. For example the difference between a straight midship section and a more complex bow area.
• Labour intensive
• Changes are a lot of work
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T-splines
The latest development is creating surfaces with T-splines technology in Rhinoceros. This is only possible after downloading the free T-splines plug-in.
This method makes it possible to insert control points at places where much control is needed without loosing a fair surface. Also you can delete control points at places where the surface is straight in order to make changes in a later stage an easy job.
Start with a nurbs (b-splines) surface from one of the methods above and convert this into a T-spline surface.
Download T-splines
Or see an instructional video
The instuctional video Lofting with T-splines is in combination with the Rapid Hull Modeling method (using Loft, option loose) a very powerfull tool. More information will follow. Or did you test it allready? Share it with us and send it to Bas Goris or Gerard Petersen
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Extra Modeling Tools
Marine designers need specific tools to improve the hull design process. Read more about the topics or download the plugins by clicking on it.
Installing Plugins is simple as only two items are crucial:
- 1 downloading and installing the .rhp plug-in file via the plug-in menu in the Document Properties menu in Rhino.
- 2 activating the .tb plug-in toolbar buttons for easy use of the commands. Active them under the menu:Tools/toolbarlayout/file/open
• ArchCut plugin automates the generation of sections, waterlines and buttocks. It can also update after changing the hull shape and loft the sections somewhere else for detailing purposes in for example 2D interior design.
• Expand plugin offers the expansion of hull plate expansion of double and single curved surfaces --
• Developable Surface Creation offers extra functionality for those who are into hull design which has to be made of developable surfaces.
• Use the "Clipping plane" command to take a look at intersections at every desired place and angle in order to show and evaluate your design ideas to other people. To see how it works, open the command help under the menu: help/commandhelp and type the command "ClippingPlane"
Example of Expand Plug-in
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Extra Naval Architecture Tools
Naval Architecture tools which are developed by third parties are:
• Rhinomarine Modules offer a lot of specific functionality for the Marine Designer. For example stability analysis, hydrostatics, linesplans and planing hull resistance estimation.
• Rhino Nest is a powerful nesting tool. Download an evaluation version and test it yourself.
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Conclusions
Hull modeling conclusions:
1 There is a basic difference between surfaces created from lines and direct generated surfaces
2 The Rapid Hull Modeling Methodology is a good tool for beginners, innovative concept hull design and parametric modeling based on self written scripts
3 RhinoMarine offers an excellent toolbox for professionals and is easy to use
4 Direct control point manipulation is comparable with the Rhinomarine approach but more labour intensive and lacks the extra automated functionality. The extra tools combined with in-depth knowledge of Rhino offer comparable functionality.
5 T-splines offer extra functionality to the other methods which need further examination.
General Naval Architecture Conclusions:
1 Rhinoceros can be used for concept design of every type of vessel as the only limitation is the skill of the designer
2 Detailed design is possible as not only hulls, but also superstructures, interiors and technical installations can be designed and modelled
3 Nesting and shell expansion is possible
If you have questions, comments or experiences, please contact me.
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