Hull Form Data

However in general the hull form surface is more complex (involving double curvature) and requiring some form of fairing. For this case the description of the surface is usually obtained from a Hull Form design (DML file) which has been released from Lines or Form.

The following steps describe the use of a Hull Form to produce a surface with the intention of using it as the barehull.

1. Select FILE \ USE \ HULL FORM... to bring up the Use Design dialog then select the required hull form and then click Use. The Hull Form Options dialog appears.

   

   Figure 3:1. Hull Form Options Dialog.

2. If the type is Mainhull, and the sidedness is one of Port or Starboard, then the Reflect option may be chosen. If the full hull (port and starboard) is created, then the Hull Form may be closed using the Cover option.

   Note:
   A single surface is now automatically generated, that is, the individual patches are stitched together.

3. The surface should be rendered to confirm that all patch normals face away from the vessel. (Any patches which are not rendered need to be reversed using the DETACH FACE and REVERSE FACE commands or the and icon).

4. If an Identify Flash is performed, the vessel boundary will be highlighted. If some interior faces are highlighted, some manual surface editing is required to achieve a fully stitched single surface (see step ).

5. If the Reflect option was not chosen (and only half of the hull form is created), the resulting single patch can be reflected (with the Copy toggle selected) to produce the opposite side of the hull. The two halves of the hull should be joined. If this has been done correctly, an Identify Flash should highlight a line around the deck edge of the hull.

6. Finally, and if the Cover option was not utilized, adding a top deck and closing the hull, using the Cover Hole icon and selecting the hull, should produce an enclosed volume suitable for compartmentation.

7. If an Identify Flash performed on the hull produces any highlighted edges, the previous steps will need to be repeated. Problems can occur due to the accuracy needed by the ACIS modelling kernel. If any patches will not stitch together then the following methods can be used to correct the hullform:

   1. Identify the patches which do not stitch together and use the DETACH FACE command or Detach Face icon to remove the offending patches from the surface. One of the ALIGN commands can then be used to modify the edges of the detached patches. All patches can then be stitched again.

   2. Identify the offending patches as above, but this time use the DETACH EDGE command or Detach Edge icon to make a copy of the edges (that means,, make a copy of the edges which are highlighted after an Identify Flash). These edges can then be used to create a formed patch, which can then be stitched together with the main hull surface.

   3. In some cases, it may be necessary to- edit the control points of individual patches. Refer to the Surface User’s Guide for further information on CPM (Control Point Manipulation).