That somewhat sad and neglected Gemini catamaran is a great example of the more is better silliness where engines and horsepower come into play…
Really, eighty horsepower?
The Gemini is a light boat (some might even say TOO light) and it does not take a lot of power to make it get up and go. Its rig HP is something close to 6.3 HP @ 10 knots of wind, 8.5 HP @ 14 knots of wind, and 17 HP @ 20 knots of wind. Which pretty much says to me that anywhere between a single 8 HP and a 25 HP outboard would be OK and my engine of choice would more than likely be a 9.9HP because the Gemini has a fair amount of windage otherwise I’d have gone with the 8HP.
Then again, eighty-fucking-horsepower…
Offhand, I just can’t see why anyone would want an engine that exceeds their rig’s horsepower unless what they really wanted was a power boat. If so, why even bother to carry around an expensive rig?
For those keen on checking their rig’s HP, the formula is HP at 10 knots of wind = .015 X square feet (use .020 for 14 knots and .040 for 20 knots). Not perfect but it is accurate enough to tell you what you need to know.
Not to quibble but I think you mean that at 10 knots of wind, HP = .015*square feet sail area.