[PSUBS-MAILIST] Trim Tanks

["ojaivalleybeefarm @dslextreme.com" <ojaivalleybeefarm@dslextreme.com>]

Hi All,

           I've been thinking about my various options for variable ballast / trim tanks.  I'm thinking of having fore and aft hard ballast trim tanks where I transfer seawater back and forth.  I think it would take two separate pumps, unless there is a pump that's reversible, since most pumps just pump one way.  With some plumbing I could pump seawater from the outside and vice versa.  I'm wondering if it would be necessary to evacuate the airspace in the tanks,  that way I could fill the entire tank without the pump having to pressurize the air in the tank.  The hard tanks would have equal straight as the pressure hull.  The pumps would need to be strong enough to pull a vacuum on either of the tanks and would need to hold the water, which could be accomplished by check valves.

 

Brian