Been there. Had those issues.
When my diesel began to die, I put a 5HP OB on the transom, but it was underpowered for the yacht (28 foot, 3 500 kg). Later I put an 8HP on the back which was about the correct power, and then lastly I put on a Tohatusu 9.8 HP 2 stroke OB because it was 2HP stronger and about 10kg lighter. Then one day at the yard I put the OB into the transom well to see how much it would protrude (i.e. above the deck level would equal the depth of the leg below the transom well if I cut a hole).
The story is here with photos:
groups.google.com/g/compass-yacht-group/c/4U5qWlntOooThe inspiration came from James Baldwin here:
atomvoyages.com/improved-outboard-well/Issues: fuel consumption will be about 3 litres/hr compared to a diesel's 1 litre/hr for approx 10 HP. But it addresses your main issues of cost and that you can relatively easily put the outboard into a dinghy and take it home or to a mechanic to work on it. Recently I (had to) learn how to clean out a carburettor and fuel bowl while in the cockpit. I'm happy to have learned how to do it, as well as I buy a service kit online each year and service it myself (spark plugs, impellor, greasing, lower leg oil change, etc). It allows you to clear weed from your propellor and it puts the noise of a motor far to the rear and outside of the yacht.
That's the main points I can think of now. For me it was mostly an economic choice, but I do like to sail with no propellor drag now, and serviceability of the motor.
The OB well was made from 18mm plywood, I think. It's in the Compass Yacht post above. To join the plywood to the f/glass of the hull, I sanded away the paint and really roughed up the surface to allow a good bond between the epoxy/ thickened epoxy, the hull's f/glass and the plywood. Although it is above the waterline a few inches, it has never leaked. It has survived 8 years now of winter storms, some with wind against tide. No leaks.
PS thanks Graeme, I was writing the post ))
