How can RC cars run on water?

Last Updated on December 1, 2023 by Jaxon Mike

Before examining how RC water cars operate, let’s first look at how standard RC cars work on land.

A basic RC car has a chassis that houses the internal components. This includes:

• Motor – Provides power to turn the wheels. Usually electric brushed or brushless motors.
• Transmission – Gears that transfer rotation from the motor to the wheels. Can be single or multi-speed.
• ESC – (Electronic Speed Control) Regulates power from the battery to the motor.
• Battery – Provides electrical energy. Rechargeable LiPo batteries are common.
• Wheels – Grip the surface to propel the car. Made of rubber or foam.
• Suspension – Absorbs bumps and allows the wheels to maintain contact. Springs and shock absorbers.
• Steering – Turns the front wheels to change direction. Controlled by a servo.
• Receiver – Gets input from the transmitter and controls components.
• Transmitter – Handheld remote that lets the driver control the car.

For land operation, the wheels provide critical contact with the surface. The tires grip the ground, allowing the motor to propel the car forward. The suspension helps keep the wheels in firm contact even over rough terrain. This traction is what gives the car maneuverability and speed.

Buoyancy is Key for Water Operation

The key difference for RC boats is that solid wheels don’t work on water. Instead, a boat 

needs components that will help it float and prevent it from sinking.

Several elements provide buoyancy:

• Hull Design – The overall shape of the boat needs to displace water effectively to avoid submerging. A v-hull or catamaran hull works better than a basic box-shaped chassis.
• Floats – Attaching external floats to the sides of the car increases displacement and buoyancy. Floats usually made of light foam or hollow plastic.
• Sealed Components – The internals need to be protected from water to prevent electrical shorts and corrosion. Waterproof plastic skins or marine epoxy coatings are common solutions.
• Lightweight Parts – Boats need to use lightweight materials to reduce overall mass. Lexan plastic instead of metal parts where possible.

The hull and floats provide the main buoyancy to keep the boat on the surface. Careful design is needed to ensure the chassis displaces enough water to match its total weight. Additional floats can supplement the hull to increase stability and prevent rolling over.

Making the components waterproof via coatings or seals keeps the inner workings safely dry when running on water. Reducing weight further aids flotation to limit how much the hull sinks into the water.

Propulsion Options for Water-Based RC Cars

Besides floating, the boat needs a means of propelling itself forward across the water. Wheels are replaced with alternative propulsion systems optimized for water operation. 

Common options include:

• Marine Propellers – Propellers mounted under the hull push water behind for forward thrust. Similar concept to full-sized boats.
• Jet Drives – An impeller inside a jet housing sucks in water and expels it at high velocity to propel the craft. Also fully steerable.
• Paddle Wheels – Side paddle wheels act like oars cutting into the water. Simple and efficient for smaller RC boats.

Most RC water craft rely on marine propellers or jet drives. Propellers work best for higher speeds, while jet drives provide superior low-speed control and maneuverability. Paddle wheels act more like oars for basic propulsion.

The propulsion is powered by an electric motor just like a standard RC car. But the transmission and gears are designed to transfer the rotation to the water propellers or jet drives instead of wheels. This enables the boats to produce thrust in water.

Steering is Handled in Different Ways

RC cars steer with the front wheels turning side to side. For boats, steering relies on:

• Rudder – Vertical rudder fin moves left and right to steer, just like full-sized boats. Used with propeller propulsion.
• Deflector Nozzle – Redirects jet stream to either side for steering on jet boats.
• Tank Treads – Each tread spins independently to turn the vehicle. Often used on 

amphibious models.

Rudders act as the steering control for propeller boats. Deflecting the nozzle of jet boats helps steer by aiming the jet stream. Tank treads of amphibious vehicles rotate each tread in opposite directions to turn.

Some RC boats utilize multilink radio controls to adjust both speed and steering. This allows fine control over direction and maneuvering on the water.

Other Design Considerations

RC manufacturers have refined their watercraft products over the years. Here are some other design elements that improve performance:

• Water Cooling – Circulates water through the motor and ESC for better cooling. Prevents electronics from overheating.
• Trimming – Adjusts the angle of the propeller in the water to optimize performance. Allows boats to plane on top of the water at high speed.
• Servos – Waterproof servos used for rudder control. High torque for positive steering even in currents.
• Prop Guards – Protect propellers from damage if boats bump into each other or solid objects.
• Bilge Pumps – Small electric pumps remove collected water from inside the hull. Keep electronics dry if water seeps in.
• Kill Switch – The safety device stops propulsion if triggered. Prevents boats from running away unmanned.

Smart hydrodynamic designs, robust propulsion, and special electronics allow these RC boats to successfully drive on water. With the right components, radio control vehicles can now transition from land to water operation.

FAQ

What bodies of water can RC boats run on?

RC boats are best suited for calm waters with minimal currents. Small lakes, ponds, pools, and protected harbors are ideal. Larger bodies of open water with significant waves are more challenging for the small craft.

How fast can RC boats go?

With the right power system and hull design, RC boats can reach speeds over 50 mph! Faster boats need a v-hull or catamaran design to plane on top of the water at high speeds.

How long does the battery last in an RC boat?

Run times vary based on the capacity of the battery, motor size, and operating speed. At full throttle, batteries may only last 5-10 minutes. More moderate speeds can extend operation to 15-20 minutes on a charge.

Can you operate RC boats in the ocean?

It’s possible, but waves and saltwater create extra challenges. The boats need extra seals and buoyancy to handle waves. Salt water is very corrosive and will damage components over time.

Do you need a license to operate RC boats?

In most areas, RC boats can be operated without any licensing. But it’s important to follow basic boating rules and be courteous when running them on public waterways.

Conclusion

It was once unimaginable for RC cars to do anything but drive on solid ground. However consistent improvements in technology and design have enabled these hobby vehicles to hydroplane across small bodies of water just like motorboats.

With careful attention to buoyancy, sealed components, alternative propulsion systems, and steering mechanisms, RC cars can run on water as well as land. Advances in materials and electronics will likely lead to even more versatile amphibious models in the future.

For now, RC watercraft provide a unique way for enthusiasts to enjoy driving their vehicles on lakes, ponds, and pools.