Hope it is okay to post this link... mods please feel free to edit and to scold me if this is not okay and I won't do it again. It is not a commercial site. http://blog.saleae.com/tuning-a-perfectly-good-sailboat-into-an-engineering-project/#respond This guy is doing a direct drive install of a '4201 motor. It doesn't say what prop size or pitch he is using or motor speeds. It also isn't clear if he is using a left hand prop or the bidirectional fan. Can't see his thrust bearing setup or shaft coupling but since he is mounting the motor horizontally he is obviously using some sort of flex coupling. You might want to contact him, and wait until he can give you some motor temps and other performance figures after testing the completed installation. Of particular importance is the prop you are using. A smaller prop with less pitch can turn faster for the same power, improving motor cooling. At least up to a point of course. I need the bigger prop at higher pitch for getting usable regeneration from my slow little boat and don't mind the slight speed reduction under sail. Bigger prop, lower shaft rpm and you might not need to go big and slow for your prop if regeneration isn't a major consideration for you. Just remember that there is an envelope you really need to remain inside of. Smaller props turning at faster speeds beyond a certain curve will of course increase cavitation and resulting slip so you can only go so far without taking a performance hit. This is more true with displacement hulls than with planing hulls, of course. Maybe hold off and see how this guy's installation works out. His boat is a catalina 30, and the old engine was an atomic. His results will have some relevance to you and also to me, actually. Did you look at the thrust bearings at Glenn-L yet?
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