Another vote in favor
I actually have the original 2qm that came with my 1980 H33. You don't want to know how many hours I have on it, and, after a top end job two years ago, I expect it to go many more. It has a rating of 14 hp continuous, 15 max, so it is about the same size. Although I do everything to keep my boat light, the fact that I have lived aboard for 16 years and cruised it extensively, probably means it has more stuff (and junk) aboard than most, and thus is heavier. 500 pounds of ground tackle, lots of cruising add ons and spares, etc. etc....you get the idea. Anyway, with that load, the little Yanmar can still push the boat at a bit more than six knots on flat water with a two bladed prop, although my cruising speed is usually between 5 and 5.5 knots. So, although I do think it is about the minimum size for the boat, it is OK. Terry mentions the issue of fuel consumption with the bigger engine. In addition, a bigger engine would spend a lot of its time not working very hard, and Yanmars (and most diesels) DO like to work hard. Personally, I see no problems with salt water engines, and they are much simpler. A very good mechanic (not American) once pointed out to me that a correctly designed salt water cooled engine, properly taken care of, will last about 90 to 95% as long as a fresh water cooled engine....he pointed out that the whole heat exchanger system was originally designed so that Americans could have hot water showers, not to prolong the life of the engine!!! Anyway, my experience with a salt water cooled engine has been excellent, so I would not shy away from one. Good luck with your H33...it is a great boat.