Naval Architecture New Zealand
Finite Element Method
Built Boats can develop any hull shape, whether it be a powerboat or sailing hull, for any desired purpose, pleasure, competition or work.
Once the owner has selected their preferred concept, Built Boats will produce a detailed 3D exterior ‘computer generated’ model, from which the shipyard can take accurate design information.
Hull and Appendages CFD stands for Computational Fluid Dynamics and is a method to simulate the (water) flow around a hull or its appendages, such as keel, rudder or daggerboard. The yacht and the surrounding water is modelled by small elements on the surface, so called panels. As in towing tank tests, the result of the CFD calculation is a prognosis of the lift and drag (resistance), as well as the momentums and the centres of effort.
These data are transferred into so-called VPPs (Velocity-Prediction-Programs), where the calculation of the yachts equilibrium and its speed is made. Compared to towing tank tests, CFD is much faster and less expensive, however the handling of this tool and the interpretation of the results need some experience.
FEM stands for finite element method, where the part, which has to be calculated, is build up of a large number of small (finite) elements. The behaviour of the single element under load and its interaction with the neighbouring elements is calculated and allows the engineer to analyse the whole system.
FEM is the best way to predict the behaviour of complex structures and laminate lay-up with respect to strength, stress and deformation. The calculations are used for the weight optimisation of complete yachts or yacht structures, or the prediction of flexing and bending, which is very important especially for big yachts.