Tom...here's a picture of an Orca that can do barrel rolls underwater...note the independent forward vanes(fins)and the large dorsal fin.
Paul...fear not, Andy is cracking on with the shark, but work commitments are slowing him down, plus he's up to his ears in little jobs for people, (such as the turbine for my tractor) I spoke to him the other night, and on top of all that, he's not been to well recently, so things are running slowly at the present.
Once the hulls arrive and I have an idea of what's going to be what, I'll let you know...
Rich