SummaryA methodology to model hull forms with bulbous bow and parallel midship section

Rapid Hull Modeling

ShipDesign, YachtDesign, NavalArchitecture

To start a ship design we need a hull form. This method might be particularly useful for people who are starting out using Rhino for ship design.

Ships with a bulbous bow and a parallel midship section are quite difficult to model nicely and accurately.

This method makes it possible and is extremely fast. The methodology was created by naval architect Bas Goris and marine rhino trainer Phil Shapiro and is distributed for free at http://www.rhinocentre.nl/maritime_toepassingen.htm

Download the ZIP file which contains a PDF tutorial in English and a 3dm file. Take a look at the lines plan to see the high quality of the surface.

It is also possible to generate other types of hull forms by changing the master curves

We hope this method will evolve and expand when other people start using it and tell us their comments or improvements. Show us your results!

Best Regards

Gerard Petersen

Naval Architect and initiator of Rhinocentre

QuestionWhat do you need to model a ship?

Bas Goris says:

There are two options:

1. To start from scratch. Only thing you know is the Length, breadth, height, draught, displacement, centre of buoyancy and roughly the kind of shape you want (U, V or S shape?; parallel mid body?; bulb? Flare?). The Rapid Hull Modelling method is a good option for basic designs.

2. To use an existing lines plan and change it if necessary.

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QuestionLets say we have an existing 3D Surface of a hull, like the one shown above. Knowing the Rapid Hull Modelling method (based on "loose loft" in Rhino), would it be possible to extract the "basic lines" or even the "control points" of these lines back from this existing hull? (Bas Goris)

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QuestionIs there anybody who wants to design a Rhino script to manipulate the basic dimensions of the Rapid Hull Modelling Method? (Bas Goris)

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Remarks by K. Huizinga of KHMB Y&S Design, Noordwijk:

A very interesting idea and an eye opener. But because these lines are very odd to the average ship designer, only useful when the 'Basic lines'(control stations) can be generated from 'real life' criteria such as:

- Main dimensions

- Displacement / block- and/or prismatic coefficient

- Longitudinal centre of bouyancy

- Bulb cross section area

- Waterline (cwl) form and entrance angle

- Bullwark line

- Some other waterlines and/or frames and or buttocks geometry because of other (mainly General Arrangement) design criteria.

Furthermore a (parametric) coupling between the Basic lines (control stations)

and the generated surface(s) (preferably interactive) would be very, very nice and useful.

I presume that Rhino has to be altered/changed for this item.

When it is possible to generate a hull with the mentioned (and possible other shipdesign) criteria,

I'm convinced that the most conservative ship designer will throw his lead dolphins away and all the other shipbuilding software will be suddenly obsolete !

This method is scribtable. I have seen an working rhino script using this methodology with parametric input already. It is not yet published.

The basic lines can be generated from the criteria like:

-Main Dimensions; L, B, D, T

-Bilge radius

-Length of midship section

-Upper angle of bulbous bow

-Lower angle of bulbous bow

-Bow forward flare angle

-Bow side flare angle

-Flat of bottom in and out angle

-Flat of site in and out angle

-hight above location of propeller

-angle of centre line at propeller

-etc.

The displacement and COB can be found via try and error. Due to the few basic lines, not too much work.

Question