Hiya, I guess a lot of it has to do with what you are trying to move ie the weight of your vessel? I have a 40ft
steel keeler weighing 15 tonnes loaded & run a Ford Lees
marine 60hp tractor
motor through a Paragon hydraulic box. She's an oldie as is the
boat (1965) but it pushes along at 9kts at 1100rpm (max) & 3ltrs an hour. A friend says put a
Yanmar in at half the weight but "hello", I would have to do probabaly 2100rpm to get anywhere near the speed of the Henry (Ford OK?)and how much
fuel would it burn? and what does a
Yanmar cost?? There are motors on Trademe that would probabaly suit your needs?? good luck.