I am already working on lines of what you suggest, developing my own stern lines faired into a single prop - the real Blue Marlin is a single prop.
John, thanks for the thoughts, interesting concept but i think its not practicable, the weight needed to be moved around would probably be too great, plus actually finding a place to fit it! At 1:175 I am surprisingly limited to space.
Adam, I agree with your comments, at the moment I am working on the concept of 4 tanks and 4 pumps, inidividually controlled. I will see how this works when I eventually get to the test tank stage. I am working on the idea of having a removeable deck, so I can test with the deck off, and modify as required.