submarine hull dumb question

Hey all, just reading up for fun on home built submarine designs (yeah i know ) and was looking at materials readily available for hulls.

-can poly type materials easily be bent and welded seamlessly at 1/2 inch thickness or more in large sheet dimensions?
-what are the simplest methods of constructing a concrete mold?
-could concrete sheathing or metal sheathing of concrete (8-10 guage steel tank) work depending on metal composition regarding shrinkage and load cycling, or even having a pliable separation between the two?

I have looked at a lot of posts etc but nothing at all regarding these questions, thanks!

ps i own a flintlock and that's not very practical either...just plinking around ya know. seriously.

 

Even the C.S.S. Hunley didn't have any concrete in it,and it sank , anyway.

 

Acrylic is commonly used in submarines; it can be bent, and there are special chemical welding techniques available for it. Not easy to do.

As for concrete- yes, it can be used for submarines, but the engineering is quite complex. See:
http://www.boatdesign.net/forums/boat-design/concrete-submarine-24361.html
http://www.boatdesign.net/forums/boat-design/submarine-yacht-project-13844.html
among other threads... the issues involved in using concrete for a submarine have been discussed in considerable depth over the last few years on here.

 

yeah, i read all those, that's why i'm asking these questions. I didn't see the *thick* metal hull (3/16 or more) over or under concrete addressed- more of rebar and wiring/fiber in mix etc. My idea was almost like a two hull of different materials question. And, if anyone had experience or know about pressure and stress on poly joins and how difficult they are...i'm in the process of just looking at all of these things. So any ideas are welcome. I really am thinking about reinforced metal tank designs though.

 

like with something like this.

 

that was an example of the shape, mind you...