|
Hi Alan. I bought these Firgelli actuators because of the simple design.
Basically it's a piece of extruded aluminum tube and two end caps. The
square tube is continuous without seams. It has ribs inside
that stiffen the tube, and are used to hold the motor in place. I've taken
one apart and it's very simple. To pressure compensate the unit I just need to
bore a small hole in the back end cap for the oil to move through.
To seal the whole thing I'm covering the tube/body with fiberglass up to
the end where the rod pokes through.
As for the wires, I'm using a small PVC female threaded coupling that is
fiberglassed into the back end and the wires pass through this coupling. It gets
a hose barb fitting screwed into it, and clear vinyl tubing to the thru-hull
where there's another hose barb threaded into the welded thru-hull nipple.
For general purpose sealing of all tubes, hoses, fittings and whatever,
after all the clamps and/or parts are threaded, I'll be using a liquid urethane
product call Vulchem as a secondary sealer. You paint it on over the hose clamps
and threaded fittings and it creates a flexible but tough over-seal. I've used
it for many years and it is tough stuff. The beauty is if you need to
dis-assemble a connection you use a knife and slice through the Vulchem, then
peel it off. It has the consistency of rubber, resists sunlight, can take a
beating, stays flexible for years, and comes in gallon cans.
I first saw it used as a pour-in rubber liquid around built-in swimming
pools where the pool "cap stones" meet the surrounding concrete patio. It lasts
for years in direct sunlight and will withstand foot traffic. I've used it for
sealing things like galvanized roof-top air conditioning ducts ( big stuff on
commercial buildings ) and gone back years later and it's still looking good.
You could think of it like the Rhino coatings used on pick-up truck beds.
Chemically similar.
As for the articulating arm.....well, I'm pretty busy trying to get my sub
in the water so the arm will have to wait. Besides, that thing Vance is working
on looks like a real possibility. I saw the one used on the old Delta sub ( in a
video ) and it was amazing how simple and quick it was. No wires, tubes,
hydraulics or anything. Just a grabber on a swivel joint that could extend in
and out. I think that video is still around. If I get a chance I'll see if I can
find the link to it. I think it was on Youtube. The old Delta sub is still in
use today. I visited with the guys who own it in Moss Landing ( near Monterey )
and they were working under contract for the Monterey Bay Aquarium
folks, doing maintenance on under water seismic sensors in the Monterey
Canyon. Something about measuring land slides etc.
Frank D.
|