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There's a company called Bellamare that makes things like
instrumentation canisters for UW use. The also make 14" spherical plastic buoys
rated to a depth of 1,000 feet that provide 45 lbs of lift and cost only sixty
some bucks. They'd make great emergency buoys, but if you had an appropriate
space in your PSUB design, might also be built in just for the lift at an
economical price.
Alec From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Stephen Pearce Sent: Monday, April 23, 2007 9:34 PM To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] Glass microspheres idea & why ? Peter
I think that the Titanic / Bismarck timber decking would have had plenty of time to absorb enough water to swell back to its original size or larger and may have been made of a timber other than pine in the first place. As a volunteer many years ago I helped recover some of the timbers from the wreck of HMS Pandora. Oak Timbers from this wreck contracted by as much as 25% after being treated and dried out. They were negatively buoyant at the time of recovery.
Having a fair bit of experience with GRP boats my suggestion is that the major problem with Pine would be it would loose the buoyancy it is there to create if it is allowed to absorb water. It would also swell and damage the GRP it is enclosed in and be subject to rot amongst other things. If you have ever replaced the flooring in an old GRP boat that had a wooden frame, many of the problems I have described are generally present.
Why not just use Glass Micro Spheres and avoid these issues.
It is a shame that you are not prepared to provide photos of the UC3 during its various stages of construction. Several P-sub members I know have a particular interest in what you are doing and what maybe unique engineering solutions you may have implemented.
BTY: Congrats on the arrival of your new Princess.
Regards
Steve Pearce
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Hi Psubbers,
In my limited knowledge - flotation - that is extra incompressible buoyancy - is used only for ultra deep dives. In my understanding tits used when a U-boats pressure hull gets so heavy due to structural loads that it itself will not be buoyant. The classic example of this would be the Trieste bathyscaphe. Trieste used a gasoline tank - absolutely incompressible - but not that efficient at - 250 kg lift pr. m3.
Who do a psubs need this when the designer is working in the 300 feet range ?? If he really needs it - my practical idea would be to make use of wood.
Dry pine wood has a density of about 500 kg / m3, and painted with epoxy or sealed with polyester / fiberglass it would form a nice simple solution in the depth range we are talking about.
Best Regards,
Peter Madsen
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