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Frank,
Thanks for the
explanation. That certainly sounds like it ought to work, it's simple enough.
But on the other hand you end up with a foot long tube poking into the hull, and
the buoy is tiny. If you want an alternative, here's what I did...
1) Made a simple
all-plastic buoy shaped like a thread bobin (a cylinder with disks on the ends).
The line is wound on the buoy, so that it'll release as the buoy tries to
rise.
2) The buoy has a nut on
it, threaded onto a a simple shaft through the hull. It's sealed by an
o-ring, with another o-ring for backup.
3) Ensure the buoy can't
turn with the shaft, so that it unscrews and releases.
The Maynards did
something very similar, a buoy (I copied theirs) and a shaft through the hull,
except their release involves shock cord rather than a thread. Details are
somewhere in the email archives, there was a thread on it I think within the
last year.
thanks,
Alec From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ShellyDalg@aol.com Sent: Friday, February 16, 2007 7:27 PM To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] through-hulls Alec, I've just got a rough concept sketch but basically I'll be welding a
3 inch through-hull into the hull, attach a 3 inch ball valve on the inside, and
thread on a 3 inch pipe with a capped end onto the valve.
The buoy sits inside the tube, and the cable is wound around a tapered pin
at the bottom of the tube.
When the valve is opened, the buoy floats out, and the cable un-spools from
the pin. I can wrap 500 feet of 1/8 inch stainless cable around the pin, and it
doesn't take up much space. I tried a sample of cable on a pin, and if I twisted
it as I was spooling it, it came right off the pin without tangling.( this of
course was just on my bench in the garage) but it seems to work just fine.
I'm sure I'll need to add an air injection port to the 3 inch tube, to blow
it dry if I want to use it to jettison excess water or air from the sub.
I expect the tube to be about 12 inches long, with half of that space taken
up by the cable and spool.
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