How to Calculate a Boat's Capacity

There are specific formulas to calculate a boat's capacity.

Every boat less than 20 feet long has a bright yellow label affixed at its stern that gives the boat's safe capacity. This label is required so boat owners don't overload the boat with weight, both "people" weight and gear weight. Included in the "gear" weight is the weight of the motor, if any. The process and formulas for establishing the capacity of a boat for cargo and people are part of federal law and involve simple subtraction and division.

Instructions

Power Boats, Greater than 2-Horsepower

1. Divide the maximum displacement of the boat by five. Subtract the weight of the boat, divided by five. Subtract the weight of the motor, divided by five. Record the result.

2. Subtract the weight of the boat from the maximum displacement. Divide by five. Record the result.

3. Subtract the first result from the second result. If the answer is a negative number, the first result is the boat's capacity. If the answer is positive, the second result is the boat's capacity.

Power Boats Less than 2-Horsepower, Sailboats or Rowboats

1. Subtract the maximum displacement from the boat's weight. Record the result.

2. Divide the result by 10 to find 1/10 the weight of the boat.

3. Multiply the 1/10 weight of the boat by 3 to determine the boat's capacity.

References

• GPO Access: Electronic Code of Federal Regulations, Title 33, Sections183.31 to 183.37