You should consider the skeg cooling a plus point. Salt water
cooling, with all of the failure modes associated with it, is probably the #1 cause of engine failure on boats. The skeg cooler eliminates the hull
feedthru, raw water pump
failures, cooling system clogging by sucking in whatever, cooling water backing up into the exhaust system when the engine is cranked for too long without starting (which can bend a rod), etc.
It is not difficult to insulate a dry exhaust. Either rock wool or fiberglass
, covered with an outer shell of lagging, works very well. Done right, the engine compartment will not overheat.
How much trouble do you have with the dry exhaust on your car? The same system in a boat can be just as reliable. As previous posters have said, this is the norm for commercial
boats. They're out on the water more in a month than most yachts are in a year.