submarine yachts based on concrete hulls are possible, available and
affordable, building cost, maintainance cost, is lower than a similar
sized surface yacht. Check out my prototype of a 20 ton yacht
submarine i developed, built, dived, tested, back in the 90ties, at:
(http://concretesubmarine.com)
Let me hear your opinion, comments, input...looking for a network to
take this a step further...
Cheers Wil