Re: [PSUBS-MAILIST]Seals (was Pressure compensation)

[Subscuba@aol.com]

Pat, The regulator I use is a simple piston first stage. It does not have a 
dial adjust. I simply changed the adjust screw in the second stage until I 
had a slight bubbling of air out of the exhaust of the regulator. This gives 
me a slight positive pressure in the air spaces without loss of much air. The 
regulator is also at the lowest part of the boat. I don't do any monitoring 
of the set up except to check the tank pressure from time to time. When I go 
up excess air vents out the exhaust of the regulator. I installed two exhaust 
valves in series to minimize any water leakage back into the air spaces.
 
 

 
 ((But I encountered a power loss when I put it in the Nautilus.  I mounted 
the
 motor externally in an aft free-flooding section; the battery box was inside
 the pressure hull tailcone; and the potentiometer was up front with me.
 That meant a LOT of wire running back and forth between components, whereas
 the stock unit only had about three feet or so.  The techs and I think this
 caused a power loss when I opened the max-thrust gate.  I can hear it kick
 in like it wants to go, but the prop slows way, way down, and almost stops.
 
 Anyway, I plan to relocate the potentiometer aft in the tailcone with the
 battery box, shorten the leads to near-stock length; and run a simple
 mechanical linkage rod from the control handle up front to the pilot's
 station: hopefully this will solve the problem, and the next time we dive
 she'll be developing full thrust.))

That sure sounds like a lot of trouble. Since I designed my own motor 
controller, the leads to the pot carry very low currents and lead length 
doesn't matter much.
 
 ((The MK that looks good to me now is the 36VDC, 101#-thrust "Monster" 
(that's
 what I heard they call it): it's available for sale now, and they had some
 pictures of it on their website when I checked it a few months ago.  If and
 when I replace the E-motor in the Nautilus, that's what I'm going to use;
 until they come out with a bigger one, that is! ))

Thanks for telling me about the 101# thrust, I'll check it out. It would be 
interesting to design a motor controller for the monster.

Have fun and dive safe,

Ken Martindale