Revised by BoatUS editors in April 2012
Not all trailers have brakes. Once a trailer reaches a certain weight capacity, trailer brakes become a requirement (requirements vary state to state). Some states even require annual inspections.
There are two general types of braking systems: surge and electric. Both aid the towing vehicle’s brake system by stopping the trailer once the brakes are applied. Surge brakes are activated by the forward movement of the trailer when you hit the brakes and the towing vehicle begins to slow down. As the trailer momentarily surges forward the actuator activates the brakes. If you are backing, as down the ramp, typically the activation is stopped by electricity from your backup light circuit in the trailer wiring and plug. Typically this will involve a solenoid which allows the brake fluid to bypass the lines. There should also be a hole into which you can insert a pin if you need to deactivate the brakes while backing down the ramp and you’ve disconnected the plug to protect your circuitry. Electrical brakes work electrically. With electric brake systems, voltage is sent to the trailer and engages the braking system when the brakes are applied. In addition, the tow vehicle requires an electric brake controller to control the electric brakes. Most modern boat trailers use surge braking systems.
The brakes can be disc or drum, just like on cars and trucks. In an attempt to cut costs, many trailer manufacturers don’t always put the best, most corrosion resistant components in their brakes. When used around saltwater, these systems tend to fail quickly. A thorough wash down with fresh water after each trip helps.
Brake repair and servicing should be done by a qualified professional. Be sure to check your state’s laws to verify that your system is legal.