> But you sometimes see that kind of a mini conning tower on
> submersibles, just to improve access to the hatch when there is
some surface chop. It just drains as you surface so there really isn't
> any extra weight up there.
It's just that it has to drain at the same rate that it rises out of
the water.
> Wasn't Joe talking about using
plywood?
> If so, I'd say that submerged the buoyancy from the conning tower
> would actually provide a righting force - along with a lot of drag!
I'd like to know the density of fiberglassed plywood before I said
that.