Safety First

Capacity Plate Guidelines

Don’t overload your boat!

Aboating manufacturer’s Capacity Plate (CP) is one of the most important safety items located at every new boat helm or transom. It lists the maximums for passenger capacity, total weight and outboard engine horsepower. The information listed only applies for boating in good to moderate weather conditions. It’s illegal to tamper with or remove a Capacity Plate.

Maximum capacity Capacity isn’t indicative of the number of seats on a boat. Instead, it’s the total number of people that could hold on to the boat’s surface if it’s swamped and waiting for rescue. Older boats may not have a CP. If you don’t have one, check the owner’s manual or calculate the boat capacity by multiplying the boat width by the length and divide by 15.

Maximum gross load (weight) This refers to the total weight of everything on the boat, including the passengers, engine, fuel, water, etc. For instance, a gallon of gas weighs 6.3 pounds while a gallon of water weighs 8.8 pounds. In a boat holding 80 gallons of gas (242.4 pounds) and a 10-gallon tank of water (84 pounds), the manufacturer would include 326.4 pounds to the boat’s weight calculation.

My 22-foot Grady White dual console has a maximum capacity of eight people and 1,300 pounds of weight — theoretically each person could weigh 163 pounds. Boat manufacturers use 150-pound people in their calculations, leaving a little room for additional weight.

Weight capacity problems Could my boat carry eight passengers each weighing 250 pounds, or 10 passengers weighing 125 pounds each? Perhaps, but neither scenario meets the CP standards and both are dangerous.

In situations where the capacity and weight approach the limit, what should be done? The captain should gently suggest that heavier passengers move to the bow, the lighter passengers to the stern, and all others distributed in between, until the boat is on plane or the engine stops.

Calculating pontoon weight Have you ever seen photographs of pontoon boats packed with so many people that the boat is heeling? A wave from a large boat’s wake could swamp it. Pontoons are stable in calm water, but with a large deck and possibly another deck on top, it’s easy to overload them. Boats with upper decks should also have a CP placed there to advise on capacity for stability. Overall weight includes the deck(s), motor, permanent gear/furnishings, added gear and supplies, fuel, water, passengers and the tubes (two or three).

To get the weight capacity of a pontoon boat, take the volume of one pontoon tube (length x width x height) and multiply it by 62 pounds (why 62, you ask? Pontoons are commonly used in freshwater, and freshwater weighs about 62 pounds per cubic foot of water). Then multiply that answer by the number of pontoons on the boat. With wave action, people moving and possible bad weather, it’s recommended to reduce the maximum weight by 20%.

Maximum horsepower rating This isn’t based on speed but the engine’s weight. Engine size can throw off the boat’s floatation ability, so the outboard motor’s maximum horsepower is determined by the manufacturer.

Changing out the engine for one with much smaller horsepower strains the engine over time, reducing its lifespan. Oversizing the engine forces the stern to sit too low in the water and it becomes susceptible to swamping by its own wake or from a passing boat.

To calculate the size of the safest horsepower for a boat, use the rough estimate of the boat length x transom width. For example, a boat with a length of 22 feet and width of 8.5: 22 x 8.5=187. The manufacturer should recommend installing an engine with 200 hp, or perhaps up to 250 hp.

Boat overloading For stability, most weight should be low in the middle of the boat with passengers’ weight evenly distributed. People should not move around while the boat’s moving, especially in deteriorating weather.

On the water, there are Rules of the Road and safety protocols like adhering to the information found on the CP. A conscientious owner will insure the boat properly. If a boat exceeds the CP limits in an accident, the insurance company can void the policy. Therefore, the captain assumes responsibility for the conduct and safety of the passengers, and common sense is necessary for boating safely. ★

Maximum boat capacity = boat width x boat length / 15

Max weight capacity on pontoon = (length x width x height) x 62 pounds. Then x that # by the number of pontoons on the boat.

Maximum engine hp = boat length x transom width

HELEN AITKEN is a boating writer, photographer and former science educator from eastern North Carolina. She loves classic wooden boats, is an America’s Boating Club member and plays in the Intracoastal Waterway.