Join Date: Oct 2008
Location: Scenic NJ
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Re: Catalina 18mkII 20' what size motor and MPG?
Personally, I think the goal with sailboats is to use the smallest engine that you can get away with. Weight is not great for sailing performance, and weight on the transom is particularly bad. Most sailboats have displacement hulls and can't routinely get over their hull speed anyway, so there's little advantage to upsizing. You just burn more gas for no speed increase, and drag your stern needlessly.
On that boat, I'd probably want a 2 or 3 hp. If you planned to cruise with it, needed an external tank, or something else that required a more substantial engine, 4 to 6 would be the absolute max for me.
Whatever line of engines you're in to, check the specs. For example, in the Tohatsu/Mercury/Nissan line, the 4, 5 and, 6 hp models are all the same block, just with different carbs and rev limiters, so you might as well go with a 6 since it weighs the same as the 4. I guess there's a slight difference in efficiency, but we're talking about such inherently efficient engines, it may be irrelevant.
I sailed a heavier Catalina 22 pretty hard for 5 years with a 5hp engine, and never wished for more power. I don't know the specific mileage (it's usually measured in volume per hour, not mpg) but they're ridiculously efficient. I used to pull the fuel line on my engine to run it dry and it would run for 10 or 15 minutes on the ounce or two of fuel left in the system.
My Boat Log, or "blog" if you will:
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