Building a toy electric motor boat can be a fun project for children. There are a number of different ways to do it. The boat can be an old toy boat, a milk carton, or a soda bottle. The boat can be propelled by having the motor run a propeller in the water, or by using fan propulsion. It is all up to you.The important thing to remember is to make sure that the boat will still float after the additional weight of the motor and battery are added. If not, you need a larger boat.
Wash out the milk carton and turn it on its side. Cut a 2-inch by 3-inch rectangle out of one of the large sides. This will be the top of the boat. The cut should be located in the middle of the boat. This will aid in keeping the boat balanced.
Set the motor and fan on top of the boat at the centre of the back end. The fan should be about 1/4 inch away from the back of the boat. When the fan runs, it should blow air behind the boat.
Secure the motor to the carton with duct tape. Do not cover any of the motor-cooling holes. This could cause the motor to overheat.
Plug the 9-volt battery into a 9-volt battery connector. One end of the connector plugs into the battery. On the other end of the connector is one red wire and one black wire. Use a red wire to connect the positive terminal of the motor to the positive red wire of the 9-volt battery connector. Then use a black wire to connect the black negative wire of the battery connector to the negative terminal of the motor. Alligator clips can be used to hold the wires onto the motor terminals. The fan should start running at this time.
Set the battery inside the front end of the boat by setting it inside the hole that was cut in the top of the boat. This will allow the battery weight to help compensate for the weight of the motor and fan at the back of the boat. Set the boat in water and watch it go. If the boat runs backwards, reverse the wire connections on the 9-volt battery.