Question:

How can I get hydrostatic data without a geometry model? Sometimes it is not easy to get the lines plan when we're on board the ship, and all we have is the stability book.

Answer:

We do not currently have an automatic way to match a hull form to hydrostatic properties. However you can make a quick model as follows:

1. Using Section Editor,

1a. Create an approximate midship section from the known beam and depth of the hull (SE command: Station@ location).

1b. Copy this section to the fwd and aft locations of the parallel midbody (SE command: Station@ location Copy)

1c. Create one or two stations fwd and aft approximating their assumed forms.

1d. Write this GF to a file in case you want to go back to this point (SE command: Write SAVE.GF)

1e. Fill in more stations by interpolation (SE command: Fill).

1f. Write this GF to a file and Quit SE.

2. Read the GF into the main program (if it has not already been read automatically).

3. Compute hydrostatic properties at a draft near the one of most interest (Command: GHS draft).

4. Compare displacement and LCB with known hydrostatic properties. If there is significant difference,

4.1 Read the saved file into SE (CLEAR SE Read SAVE.GF).

4.2 Move fwd and/or aft stations to change displacement and LCB (SE command: Location).

4.3 Repeat above starting at step 1d.

With a little practice it should be possible to create a rough approximation to the hull in less than 1/2 hour.