Hi Ian. Although there's not many guys doing the big subs, don't get 
  discouraged by the lack of discussion on them. It's just that most guys 
  can't afford a sub that big, or can't imagine building it 
  themselves. 
  Listening to Peter, it looks more and more possible. He has the advantage 
  of having built two smaller subs and gone through the learning curve, plus 
  it's pretty obvious he's really smart! I for one can't wait to see your sub 
  when it arrives, and I'm sure I speak for most of the guys when I say full 
  speed ahead on your project, and of course, let me know if I can help in any 
  way. Maybe I can bring my little sub along and drop it in the water next to 
  yours for a "submerged  inspection". 
  I can just imagine sailing a big sub off some where and cruising the 
  coast, stopping for beers at the local marina. Man, what a blast that will be! 
  Frank D.