HI Rod, I have just bought
Windchaser and she has an 18 hp Tohatsu 2 stroke in the well. The PO took out the old 10 hp 4 stroke Honda and, having a boat building trade, made the well a bit bigger to suit the bigger motor. He wanted something to go hard against the wind and swell.
Yesterday I got back to Rockhampton from bringing the boat up from Southport on the Goldcoast, a distance of about 300 nm. My previous boat, a 27 foot Endeavour which only got out to sea as too many problems emerged, had a 1GM10 of about ten hp. Needless to say, the grunt from Windchaser's outboard outperformed the old diesel.
Some of the stuff I went through was quite rough. Often I motored since the wind was from a bad quarter or there was no wind. Having the motor in the well I think it was much better protected than if it was outboard since I went through extremely peaky tide-against-wind stuff up to two metres plus the 'mad mile' of the Wide Bay Bar to get behind Fraser Is had peaky waves going everywhere. In these conditions I had wave slap against the stern and the boat was being shoved every which way. I wondered if the motor had been more out stern if it may have got water over the motor and the stern was lifting up a bit so perhaps cavitation. But I have not used a Top Hat with the outboard out over the stern so I really can't compare, just in my opinion I would have had more trouble if the motor was not in the well.
Even though I think the outboard in well is more sea worthy, it takes up heaps of cockpit space and I am much closer to the noisy stinking thing. For more of a cruising application, I think I would put the motor out the back. I think I would go for a smaller motor too. Those are the changes I am thinking of doing but at this point, the setup performed incredibly well so I don't even want to complain about the noise and stink.
I cruised on the flat at 6 knts. To conserve fuel I did 5 knts. Could do seven if pushed and could do 6 knots against wind and tide but motor was getting toward WOT and I went through 20 litres in about 15 nm. However, coming up the Fitzroy River with the tide, I did 25 nm and used about ten litres cruising at 5 - 6 knots.
In my opinion, if you find a boat which overall ticks the right boxes, then you can change outboards around for not too much money. Inboards definately have advantages but I think if you like a boat that has an OB in well and you want on the transom, it is easy enough to change. But if you want inboard diesel and the boat you like has an OB, it is costly to change.
I would have preferred an inboard diesel as that is what my last boat had, I like diesel since I have used many diesel motors and I can do servicing. However, I bought Windchaser with an OB since the boat overall was what I wanted and I want to get out sailing rather than keep looking : ).