As a side note, I've been experimenting with brushless cans for the fix-a-upper Aquabat that Ron kindly brought along to the Dive-in for me.
I'm decided to splash out and go with a $6 motor-
http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=5354I tried this with the original 50mm twin bladed prop in a bucket- well I was impressed, I could just about hang onto it with three lipos and my watt meter showed it was pulling about 10A. This is well within the motors spec.
That equals about 110 watts or so.
Should be a bit more lively than stock (not really trying to compete with a Subdog on with this one as the hull shape is quite draggy), as the original mild 500 sized motor was only drawing about 25 watts, which is about right for a 6 volt 4AH gel cell.
I'm also going to try the twin leveller split rear hydrovane approach that Norbert uses on his Dolphins, as torque roll is likely to be a bitch with a 50mm prop cranking about 10k on a sub that displaces about 2kg.