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Joe, Vance, and all. I haven't found the old catalogue but I'm looking on
the net for these things.
As to the pressure and water, the set-up I saw was not designed for a wet
application. Without a pump, the internal pressure of the system isn't much, and
in fact wouldn't be anything until you turned the wheel to move the rudder. But
it IS a closed system. I'm thinking of two ways to keep the water out.
First, add a small pressurized oil tank to the system, and with a scuba
regulator, keep the pressure in the tank slightly above the water pressure
( at varying depths/pressures )
As the system is a closed loop, the differential pressure across the
positioner would be the same as if there was no external pressure ( sea water
)
The other idea would be to put the positioner in a compensated
container with the shaft extending through a seal. Again, you'd need to
have a scuba regulator or other air line keeping the pressure inside the
container slightly above ambient.
The positioner is nothing more than a double acting hydraulic cylinder.
They run about $100 or so, and are easy to get, modify, fix, and replace.
The master cylinder is pretty much the same thing, but it had a
rack-and-pinion set-up on it that moved the piston back and forth, moving the
fluid from one side to the other through the positioner.
I can't remember what the cost on this thing was, but it was pretty
cheap.
I'll keep looking, and maybe call a couple of hydraulic equipment
suppliers to see if they have any leads.
Frank D.
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