# Lighten flywheel to increase top speed?

i have an old gasoline fueled skiff that only makes 3-4 knots. I find this to be strange since the engine is rated at 10-12 horsepower. It isn't that heavy and i figure it should be able to do more. Could this be because the flywheel is TOO heavy? And i'm talking MASSIVE. it's like 50kg. Maybe even more

• An important parameter for the maximum speed of a boat is the "hull speed" which depends on the length of the waterline: $V = 1.34 \sqrt(L)$ where V is in knots and L is in feet. To pass that speed, you need enough engine power to get the boat to "plane" by climbing on top of its own bow wave. Also, your rated engine horsepower is only relevant if it is properly matched to the propeller, otherwise you can't use the available power. – alephzero Sep 25 '18 at 18:27