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Metal Hulls and Waterproofing Techniques

Metal Hulls and Waterproofing Techniques

(OP)
Hello all,

I'm curious about ways to make metal hulls (built from scratch) airtight and waterproof. I haven't built one yet but if anyone has could you please share your experiences? I want to build a remote controlled model (about 4' long) from metal to make it a deep diver and have more control over the size. My worry is how to prevent leaks as the pressure increases substantially (no pun). There must be some true and tested engineering techniques for connecting two halves of the hulls such that no spaces are left at the seams. Maybe glue a thin piece of rubber all around? Or maybe even de-pressurise the inside to suck the air out and force the hull-halves to stick together tighter?

Thanks!
--Max

RE: Metal Hulls and Waterproofing Techniques

Hull halves?  As in canoes glued gunwale to gunwale?  That would be an unusual way to make a pressure hull.




Mike Halloran
Pembroke Pines, FL, USA

RE: Metal Hulls and Waterproofing Techniques

If you want it to stay joined, weld it (which is how they joint the rings real submarines are made from).

If you want to be able to split it again, buy a cheap water/explosion proof torch (Pelican do some really cheap ones) and look at how they use the O-Ring to keep it watertight.  The secret is to design it so the water pressure squashes the O-Ring ever tighter, improving the quality of the seal when it is most needed.

What did you have in mind for through-water remote control?

A.

RE: Metal Hulls and Waterproofing Techniques

(OP)
Thanks for replies, guys.

Mike, yes two 'canoes' design. This is a model so I want to be able to take it apart and fix/add/modify easily at anytime. Here are someone else's pictures to give a visual: http://home.planet.nl/~bergh601/submarine/pics-construction-t.html

zeusfaber, I like the O-Ring idea, thanks. I want them to stay joined but only when in water, of course :) Otherwise as I said above I want to be able to take it apart when I need to make modifications/adjustments e.t.c. so welding everytime would not be convenient.

RE: Metal Hulls and Waterproofing Techniques

The "two canoes" concept is going to leave you with a very long join - lots of opportunity for a tiny blemish to lead to a flood.

One possibility - again stolen from the way real submarines are built - is to enclose all the stuff you need to keep dry in a smaller container which is designed purely to stay waterproof and resist pressure, then nest that inside a thin outer casing which needs do nothing more than look pretty/hydrodynamic/aggressive and to flood, vent and drain freely.

Some advantages to this approach are that

1. Your pressure hull can be optimised for being a pressure hull, with the shape chosen to minimise sealing and pressure resistance problems, and the size restricted to what you actually need.

2.  Your outer casing can look as exotic as you like without your having to worry about watertight integrity and pressure resistance - and you can modify it to your hearts content.

3.  Because the free-flood space between the pressure hull and the casing doesn't provide any buoyancy, you'll need much less ballast - vastly reducing the number of back injuries you suffer trying to get it home from the seaside.

A.

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