For that size boat a gallon should be more than enough for two coats overall, plus and extra coat or two at the waterline and on the leading edges of the keel and rudder. Depending on the brand of paint, you might also want to mix in a little brushing thinner --- it will make the paint go on much more smoothly (and, for reasons that I've never fully understood, seems to make the paint stick a bit better).
It's in the lazerette?
Oh, never mind...
I didn't REALLY need it anyway.