Entering a Table of Offsets (ProSurf Only)

If you have a full table of offsets (more than 25 offsets or so) for an existing boat/ship that you wish to match up exactly using the ProSurf package, you should follow the steps below. If you have less that 25 offsets, it may be faster to use the File-Create Boat command and the Edit-Set Point command method described in the section on "Setting Offsets in ProBasic or ProSurf".

A. Use the Offsets module to enter offsets for each station. The offset half-breadth and height values must first be converted to decimal form if they are in some other form, such as feet-inches-eights. See the Offsets module manual for more details.

B. Verify the station shapes using the Body Plan display or the Hull Draw module. You want to make sure that the station shapes looks good before you fit surfaces to them.

C. Correct any errors using the Offsets or Digitize modules. The Digitize module can be used with a mouse for doing interactive editing of station shapes.

D. Convert this "Station Definition" to a "Surface Definition" using the Convert Hull module. This program fits or "skins" the stations with one or more B-spline surfaces. A "Station Definition" of a hull describes the hull shape using only a number of stations located along the length of the hull. Station definition programs fit B-spline curves through the offset points of each station. The "station definition" is good for input and calculation, but not accurate enough for fairing and construction templates. A B-spline (NURB) surface definition is required to perform full surface fairing and lofting. See the Convert Hull manual for a detailed example of this surface fitting process.

E. Read the new surfaces into ProSurf using the File-Get Old Surf command.

Conversion from an arbitrary table of offsets to a surface definition is a complex process, since the hull being defined might have many chines separating many surfaces. Before you begin this conversion process, you need to read up on the definition of the "Station Definition" and "Surface Definition" of a hull and read about the conversion example in the Convert Hull manual.