Hi Alan. I haven't purchased any components yet, but here's what's
expected.
The electric actuator is mostly extruded aluminum, stainless rod,
gears, bushings, and a little motor geared way down for torque. Not much
empty space left over.
With a 1/4 inch FRP housing hard up against the aluminum, It's
plenty strong enough to resist the compression of so little airspace.
The bellows at 1/4 inch thick will flex in and out even after it's
collapsed by external pressure. Rubbing on the polished stainless shaft
shouldn't be bad, and maybe filling the space with some grease would be
even better, as long as it allowed the bellows to collapse completely when
retracted.
I've been working on the pros and cons of various systems for months now,
with the motor mounts and linkages done except for plating.
The aspect I like the best is replacement. I can build a complete
component ready to install with two pins, and two wires, plus hose clamps and
sealer, for about $140.
And it's tough. Should be able to take quite a beating. The wires are
small enough so I can use the same thru-hull as the thruster power, so only
one electrical thruhull on each side to control motor and dive plane.
Only 4 wires each. Simplicity at it's best.
Inside, my portable control box will have steering and dive plane angle
controlled by 12 volt toggle switches
while the four motors are set with dials. This all fits on a 6"
X 6" panel, with a multi wire cable so I can take it up on deck when I'm
motoring next to the dock.
Looks good on paper !!! I'll let you know how it turns
out.