Dave,

Thanks for the Wikipedia link. Yes, I realize that it's "conventional" with respect to the diesel, but the ability to run on the fuel cells for "weeks" sure is impressive compared to batteries. By the way, when PEM Fuel Cells are run in reverse (as a hydrolizer - not sure about that spelling), energy from the diesels would be used to recharge the Oxygen and Hydrogen storage tanks.

Bob

If it has moving parts, it'll make a recognisable signature.....and can be tracked...It's just a case of how much sound isoalization there is.....Would love a chance to IC a new class of boat one more time!

You are so right, and as long as water flows past hull surfaces there will be no lack of interesting things going on.