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Marine Software Integration

NURBS surface transformation functions.

Most of the ship design methods based on prototypes. Very often we save our time by copy and modify previous projects. Prototype can be very useful for rapid hull surface modifications. There is several different functions for hull surface transformation in Shape Maker. All of these functions can be divided into three different groups:

1. Scale transformation for complete hull model or part of it. This is most simple way to get some start point for your new design. Model can be scaled in any direction with different scale factors. Previously faired surface will just scaled and keep shape quality. But we have to keep in mind, that some of the transformations will change shape not like we want. For example different scale factors in transverse view can make bilge elliptical shape instead of cylindrical. Some important dimensions like fore and aft limits of the parallel mid body will not be exactly on the frame spacing, stem and stern-post flat bar dimension will be also transformed. All these problems can be fixed quite quickly manually. Surfaces in the model connected to each other, if they have a common edge. Modification of the edge is a kind of way to adjust surfaces to correct dimensions. After modification of the edge between two surfaces they will follow to the modification. By the way all these changes take minutes and let you to get preliminary model very quickly. Scale transformation example image Scale transformation example

2. Lengthening of the vessel. Very often lengthening is used in fishing vessels design. It is nice to keep unchangeable fore and aft parts of the vessel, but add several meters of the length in parallel mid body area. In this case possible to keep all steel structure in fore and aft of the ship same as before. It's works fine if the mid body area is previously defined on the original hull shape. As usual fishing vessel has racing of keel and, if we will use scaling of the model, we will have a different racing angle. Move block function perfectly fit for this type of the transformation. By moving fore ship block along racing line it's easy to get necessary result. Spline Lengthening of the vessel

Another transformation possibility is to move for example fore or aft limits of the parallel mid body. In this case we change shape, but add or remove some volume. It is possible to set up surface modification area affected by these changes. Changing of parallel mid body limit image Changing of parallel mid body limit

Similar transformation can be done with any surface boundary line. Changing of stem contour image Changing of stem contour

3 Changing hull volume and position of the center of buoyancy. From time to time in design process is necessary to remove or add some volume to the hull. Transformation function helps to redistribute hull volume. The transformation can be performed for all surface or for part of it. The transformation defined by shifting vector. Shape changes dynamically shown on the screen. The transformation algorithm makes major changes in hull surface areas where angle between shifting vector and hull around 45 deg. For ex. if shifting vector along longitudinal direction, minimum changes will be close to middle part of the ship and ship ends. Changes make hull more slim or fat very predictable way and not destroy fairing of the surfaces and knots distribution. Changing hull volume image Changing hull volume example"