To determine which trolling motor suits a specific boat, the weight of the boat must be known. An estimated 2 pounds of thrust are required for every 100 pounds of boat weight.
To determine the weight of the boat in question, look up the specific boat on the NADA boat directory website. The weight used should include the weight of all passengers, fuel and gear that go into the boat when in use. Next use the equation of (boat weight/100) x 2 to determine how many pounds of thrust are needed.
The speed of the water fished in should also be taken into consideration. If the water is slow moving and has little to no current, the minimum thrust is more than enough. For faster-moving waters, accommodate with additional thrust. If the boat is used for multiple days in a row without time to recharge, a larger motor provides the boat with more run time. Larger motors require two batteries to run.
The voltage of the motor needed must also take into account the length of the boat. For boats over 16 feet, at least 24 volts are needed. If taking the boat out frequently without recharging, a 36-volt battery is the best choice. Shorter boats require less voltage.