Max Horsepower Calculator

How It Works

The USCG capacity plate HP rating is a legal maximum, not a recommendation. Most boaters find 60-80% of max HP provides good performance with better fuel economy and engine longevity. Exceeding the rated HP voids insurance, violates federal law, and is dangerous — the transom may not handle the torque and thrust. Flat-bottom boats get lower ratings because they are less stable under power. Repowering with too much HP can also cause handling problems (bow rise, poor steering, porpoising).