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Re: [PSUBS-MAILIST] Pressurized double or triple layer hull ?? Any idea ?



I understand your concept, but really what your after is for your hull to hold it's designed shape, not go flat with you inside.  Three separate layers of any material are never as stiff as one layers of the same material three times as thick would be.  If you were building a internally pressured sphere, it wouldn't make any matter if you had three separate layers or one layer the thickness of all three but your dealing with external pressure.  

What were you going to do for breathing air?

Dan H.

BeniBoose wrote:

Hi all, I'm new here (just join the list this morning) and happy to find a group of people interested in personal manned subs. My name is Benoit Bissonnette and I'm a scuba diver. I'm interested in the underwater life and I'd love to eventually build a sub that would carry me more confortably into our Canadian's cold waters or deeper and longer than a diver would endure. I've read quite a bit on the subject and I have a good idea of what to expect or maybe not... I had an idea for a design and I'm wondering if you guys can give me your opinion on it. Since I would like to design a smaller sub with a smaller volume (basically giving up the cylinder shape for a more "man shaped" hull to reduce the air volume), I tough of building a solid and structured hull. The reason I'm looking for a shape like this is for more comfort (a sit position) as well as reducing the volume of air that need to be neutralized. I wish I can end up with a lighter sub that doesn't need tons and tons of equipment to move. Anyway, since the geometry of the hull won't be circular, I know that a tremendous stress will be applied on the different element of the structure. I had an idea of building let's say a two or three hermetic layer hull and pressurize each air gap with a positive pressure. If at 100ft you get around 45PSI on the structure, pressurizing the internal air gap at 30PSI wouldn't relief some pressure on the structure ?  Instead of having one structure or layer resisting from 0 to 45PSI wouln't be better to have a structure or layer resisting from 0 to 15PSI and 15 to 30PSI at the next layer and finally 30 to 45PSI for the exterior shell. Obviously, this pressure can be monitored and controlled internally as needed. I think this idea might help reach greater depth with smaller structure or eventually make subs lighter. Anyway, I would be curious to have your toughs on this. Benoit Bissonnette