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Isn't having your motor and battery in the same air
comp loop an invitation for a hydrogen gas explosion?
Hi Vance.
You asked..."Speaking of which, how are you
protecting the penetrations and electrical system?"
I plan to use thru the hull stainless steel
waterproof fittings for the penetrations. Flexible tubing for the wires with
waterproof connections at the ends, and fuses as you suggested.
You also asked..."It seems to me that the
equalization process is more trouble than it is worth for the pod, which ought
to be strong enough to dive where you expect to dive"
Since I am going to equalize the motor with air,
and since the motor is connected to the battery pod via the tubing holding the
cables, I am really not going to any extra trouble to
equalize the pod. I know the strong pvc could take
the depths I plan to dive at but it doesn't hurt to equalize the pod also. It
would actually be hard to NOT equalize the pod when my
equalized motor has wiring going to the pod and
even if I tried to block off any air from the motor from getting into the pod it
would seep thru the wires themselves. So equalizing the motor
also pretty much automatically equalizes the
battery pod in my case. As always I appreciate your's and everyone else input
and advice. Putting our heads together always helps us brainstorm
and
think things thru. I truly appreciate all your
helpful posts along with everyone elses here.
Kindest Regards,
Bill Akins.
----- Original Message -----
Sent: Tuesday, January 25, 2005 11:06
AM
Subject: Re: [PSUBS-MAILIST] Wetsub
carrier water transport systems
Launch and
Retrieval Platform--they were (are?) towed aluminum catamaran rafts with
grating decks and big ballast systems. Two divers piloted it, with the sub on
deck. Take the LRP down to 60 feet or so, release the sub, surface. To go
home, repeat in reverse. Sort of like what you have in mind, only they did the
sub transfer underwater, where there was no wave action. Mucho important when
you are trying to mate 5 tons of submarine to 5 tons of raft. Banging be a bad
thing, I can assure you.
Green gas beeze chlorine, yes. Pretty tough
on the fire fighters, who were hoping like hell that the hydrogen we couldn't
see was going to be nice and vent out of there without spitting Trojan
batteries as projectiles. I've seen a pod go like that (in the shop at Perry)
and brother, let me tell you, it ain't a pretty sight.
Leak detectors
are very simple in theory. It's just a little DC open-circuit deal that closes
when shorted by water in the bilges or wherever and lights the light. Take a
little block of PVC, attach two stiff wires a quarter inch or so apart, then
glue or screw it on the inside pod bottom so the wires just clear the surface
(1/8" to 1/4"). Then run a pair of wires from it, through the pressure vessel
wall, and out to your cockpit. Make a little cannister of PVC or acrylic or
something, as this is a wet sub, so things will stay dry. Inside, power it
through switches with a couple of 9-volt batteries to LEDs or something, and a
buzzer. Don't use the sub's main power system, as you want to know about a
leak whether you are powered up or not. Keep it totally isolated and
independant. Goop everything down so errant splashes and condensation won't
cause any problems, and you're in business. Total cost, with batteries, $17.36
or thereabouts. (Okay, I'm guessing. It might go 20 bucks).
Speaking
of which, how are you protecting the penetrations and electrical system? If
you do have a leak, and a major short, straight cables will toast a hole in
whatever is handy and blow you out of the water. A simple solution is to build
in-line fuses. Size them to maximum draw for the system and cable, then cast
them into PVC tubes using 3M goop or something non-flammable. A major short,
such as you might expect with seawater intrustion, will pop the fuses and
reduce your problem to the pod itself. We may all bow our heads now and pray
that it never happens, but should it come about, at least you'd know what to
run FROM!
As for vents, I'd use SS fittings, maybe a 1/4" going in,
and a 3/8" or 1/2" going out. Put bulkhead shutoffs near or directly into the
pod, and valves up high. Hook a regulator to a gas supply, attach it to the
goes-in valve, start a slow flow (just a little air action will do it) and you
have your vent system. If you plumb it high on the boat, then you could charge
in the water, no problem. Also, have the input line and output lines on
opposite ends of the pod. You could do it with both fittings in one
penetration, just run tubing from the input line (inside the pod) to the
front.
Compensation is another deal. If you were talking about oil, I
could probably help, but I've never used air to do it. It seems to me that the
equalization process is more trouble than it is worth for the pod, which ought
to be strong enough to dive where you expect to dive. Psubs has some really
creative guys who have experience with this, so I'm betting someone will help
you out.
If air compensation causes you problems, then you might want
to consider modifying the motor housing to improve its capabilities. That will
take some machine work. You'd want to cut a proper O-ring groove in the
sections, and root out enough metal around the prop shaft to allow a pump seal
of appropriate size to be installed. It isn't all that complicated a process,
and Dan H. has a whole machine shop up there in Pennsylvania with about four
feet of snow in the parking lot. Send it to him. He hasn't got anything else
to do, anyway-----Right, Dan?
I'm looking forward to seeing this
critter. Couldn't find you on the moki pages, so maybe they haven't posted it
yet. I'll keep an eye out. At present, I've got half a dozen Spanish speaking
roofers banging away at my new shingles, so that's keeping me busy.
Best Regards,
Vance
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