Gentlemen,

Say I want to make sure my boat does not sink even if it's full of
water.

It weighs 4330 pounds. Does that mean I have to add about two cubic
meters of foam somewhere? There isn't enough space for that much.

Or can I somehow take into account the buoyancies of fiberglass, fuel
tank, engine, and all the other stuff? Is there a method to calculate
things like that?