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Simple solution... just put a T in your pressure gauge line, and a
little check valve of the kind that's a SS ball seated by a spring. You can get
them for maybe 10 bucks on eBay and they work like a charm. I know, a small
instrumentation line isn't large enough to relieve huge volumes of
air. But what you're contending with is pesky little small leaks that go
unnoticed. Also, install a barometer in the sub. From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig Sent: Saturday, June 13, 2009 4:14 PM To: PSUBSorg Subject: RE: [PSUBS-MAILIST] Side Thruster Options Hello Alec, Your reminded me of one reason I didn't wish to go with air compensated thrusters. It was a slow bleed into the interior of a K-250 that George was running, that made the hatch dome pop out when he started to ascend, and he was lucky to of survived. This is also why I plan to install a over pressure valve much like the larger one that is installed on the KSS. Except I'll be mounting mine in the bottom of the sub so it can also be used to drain the sub after a wet exit training exercise. Regards, Szybowski Subject: RE: [PSUBS-MAILIST] Side Thruster Options Date: Fri, 12 Jun 2009 09:14:20 -0400 From: Alec.Smyth@compuware.com To: personal_submersibles@psubs.org Hi Dan,
I recall a past thread in the past on this topic, it
must be in the archives. Mine were air compensated when I bought Snoopy but
I switched to oil because the way the air compensation was originally
implemented, a little air bled into the cabin raising the interior
pressure. So I've run the same exact motors in both air and oil. I cannot
tell the slightest difference. They seem to have exactly the same power, and
even make exactly the same sound. In retrospect, I wish I'd measured the current
draw so I could compare that, but I'm afraid it's too late. Either method works
just fine.
thanks,
Alec The contents of this e-mail are intended for the named addressee only. It contains information that may be confidential. Unless you are the named addressee or an authorized designee, you may not copy or use it, or disclose it to anyone else. If you received it in error please notify us immediately and then destroy it. From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Dan
H.
Sent: Friday, June 12, 2009 8:08 AM To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] Side Thruster Options If I were to do it again I would
also go with a Minkota or similar for me thrusters. I built mine from
standard DC motors. They're ambient pressure inside and have ceramic shaft
seals. It was a lot to go through and not cheep when all was done.
The worse is the weight of them.
Speed controllers aren't really
necessary on fractional horse powered thrusters like side thrusters because of
the mass of the sub. It doesn't react fast. Just pulsing them on and
off is sufficient. Where I do recommend a speed controller is on the rear
thruster so you can slowly cruse, skimming the bottom.
Has anyone done any experimenting
with oil filling thrusters to determine if there is an increase in electrical
current draw or reduction in thrust do to the drag of the swirling oil and maybe
some floating of the brushes?
Dan H.
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