Glen,
Here is a weight and balance spread sheet that can be used to indicate where you stand with your design. You have to know where our center of mass is for each item in or on your sub, the mass of the object, and the X, Y, and Z coordinates from an arbitrarily chosen point within your sub design. While this is tedious, it is the first thing that should be started when you are designing a sub...this is not just me saying this, any worthy sub design text (or naval architecture text) says the same thing. If you are using a CAD program to design your sub, many have a built in capability (or add-on package) that will build this table and complete the calculations for you. I use Rhinoceros 3D CAD with the Orca3D plug-in. Orca3D gives me a wealth of hydrostatic and hydrodynamic information for little effort about my design.
Have just been loaned a set of K-350 plans which I will enter into Rhino 3D so that some of the questions such as what happens with trim when you have the hatch open to one side as compared to fore and aft, what happens when one battery pod is flooded, what happens when you lose a ballast tank, and what happens with a shift in position of the battery pods to name just a few of the issues to be investigated. Look to present these findings at the 2010 PSUB Conference.
R/Jay
Resepectfully,
Jay K. Jeffries
Andros Is., Bahamas
Save the whales, collect the whole set.