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Re: [PSUBS-MAILIST] New potential sinker

Dear Thijs,
 
Thank you so much for the input.  The reason I was selecting foam was because I did not know about its boyancy properties.  I thought that there might be a density of foam that had neutral boyancy and would be easy to work with.  I see that might be wrong. 
 
I am at the very begining of thinking this through and have not looked at enough data on foam yet.  Your email will be very helpful cause now I know that an alternate to foam is needed - thanks a lot!
 
It is also good advise to build a grp fairing.  I can see where that would be much much easier.
 
I am in your debt.
 
Bob T.
----- Original Message -----
From: Thijs Struijs
To: PSUBS
Sent: Saturday, June 15, 2002 6:41 AM
Subject: [PSUBS-MAILIST] New potential sinker

Bob,
 
Your design looks good. With the conus-hemisherical pressurehull in a faceted outer hull it makes me think of a Gemini space capsule in a stealth bomber. As far as i know companies that manufacture end caps also make cones. This makes the pressure hull in principle very simpel. Making the viewports and the hatch may be a little more complicated.   
 
I ony wonder why you use foam. Home build submersibles usually have pressurehulls that are light enough to float. For every ltr. foam you need almost a kilogram of lead as compensation. As far as i know foam is normaly used in very deep divings subs with heavy, sinking hulls.  Foam is also used to balance a sub when for instance the batteries are placed behind the pressurehull. You need to add some foam in order to keep the sub level. Would it not be easier to make a plywood female mould and make a grp fairing. The faceted shape makes making the mould not to compliceted.
 
Greetings,
 
Thijs Struijs