Outboard as a saildrive -- basics, curious.

[xluke]

Hello,
I recently got a new-used sailboat that has an OMC saildrive. She runs like a champ but I have never seen a saildrive unit before and am generally curious about them. They seem to be essentially an outboard. Could an outboard be used to replace a saildrive? I.e., could one create a wood/fiberglass mount (i.e. wood for structure, fiberglass to protect) all around an outboard and then drop that into where the saildrive was (thus having the lower end underwater and the upper end in the engine well) with a little glassing to keep her sealed up? If not, why? What is the difference?

Thanks!

[trantor12020]

Yes you can. There are production sailboat that uses OBM this way. The Platu has an OBM well in its cockpit. You could haul out the obm when sailing. Just note that if the obm well covers it too air tight the engine won't get enough air for running.

[haffiman37]

OMC, made this many years ago mainly based on the 25HP power head. The specific saildrive parts are a bit difficult to source, but not impossible. Even Volvo Penta made a similar one back in the late 70's based on the then Honda 7,5 HP outboard and lower unit (internal parts) from the Archimedes Penta outboard!
There are a few boats that have outboard wells from factory, but not too successful. The engines have a tendency of running on their own exhaust, they need an 'exhaust relief' above water due to back-pressure, unless you have the hatch/cover open. Corrosion and marine growth are even problems.

[Minnewaska]

Congrats on the new boat, what year is it? I have a suspicion that your saildrive dates from the era when they were fairly problematic and those parts can be harder to find now. If it's your first, research all the preventative maintenance you can find and stay on top of it. Anodes in particular.