Here's how I made a simple RC boat using a pepsi bottle.
The RF link in provided using nRF24L01+ modules.
nRF24L01+ modules x 2
DC motors x 2
L293D Motor driver board x 1
Arduino Uno x 2
Joystick potentiometer x 1
Pepsi bottle x 1
Hot Glue Gun
Silicone gasket maker
Step 1: Build the Transmitter Unit
We first build a joystick controlled transmitter unit. The joystick is used to control the direction and speed of the boat.
Construct the circuit using the schematic and fritzing diagram as a reference.
Download the Arduino sketch code for the transmitter and program your Arduino.
Step 2: Build the Receiver Unit
Construct the receiver according to the Fritzing diagram and Schematic. The boat uses two DC motors to provide differential steering and propulsion.
Download the Arduino sketch code for the receiver and program your Arduino.
Note: The capacitors at the motor and nRF24L01+ module are used to filter out EM noise disturbances that can cause erratic behaviors. You might also have to use a well designed power section if you're not using the original UNO board.
Step 3: Build the Boat
To construct the boat, I used a 2 liter Pepsi bottle. Cut open a small hatch in the bottle, wide enough to fit in the electronics.
Attach the motors to the bottom end of the bottle. You can secure them using cable ties and hot glue. I used hot glue and a silicone gasket maker to plug the holes for waterproofing.
I made the propellers using the plastic from SIM card packaging. I cut a small rectangular strip out of the plastic and shaped the ends using scissors and sand paper. To bend the plastic and give it a propeller shape, I heated the strip using a hair dryer. This made the plastic soft and allowed me to bend it to the desired shape.
I used two separate 7.4 V li-ion battery packs, one to power the electronics and the other to power the motors. The li-ion batteries had a desired weight that provided a center of gravity to my boat. If you're using lighter batteries you might have to add some weights to provide a center mass.
Insert the electronics and make the required connections. Then happily control the boat using the transmitter unit.