Boat trailer brakes are a necessary evil. They are essential to make a road trip safe, but when they don’t work or need servicing, they’re a real pain. Most states’ towing laws stipulate that trailer brakes (separate from tow vehicle brakes) are mandatory when the trailer exceeds a certain weight limit. This limit can range from all trailers in North Dakota to the whim of the highway patrolman in Missouri, but most states require brakes on at least one axle of trailers that weigh more than 2000 pounds.
Boat trailers can have either disc or drum brakes. Most trailers utilize some type of hydraulic surge braking system, where the tow vehicle’s braking rate and the mass of the trailer affect the application of the trailer brakes. Brake systems also include brake actuators, pads, shoes, discs, calipers (most companies sell complete disc brake systems) and drums. Drum brakes are found on trailers used for smaller and lighter boats, as disc brakes generally require more line pressure to be effective. Trailers with drum brakes tend to work best with loads up to about 3000 lbs GVW.
Boat Trailer Brake Maintenance
Boat trailer brake components must be frequently and carefully inspected, with worn items immediately replaced. One of the most common breakdowns that occurs to a boat trailer is in its braking system. With a well-maintained trailer brake system, you’ll spend more time driving your boat to its next destination than worrying about stopping it when you get there.
When disc brakes are used with a hydraulic surge brake coupler, it is extremely important that the residual valve (check valve) of the brake coupler be punctured or removed from the master cylinder. Failure to do so will maintain 10 to 20 lbs of hydraulic pressure on the disc brake units and will lead to rapid brake pad wear and possibly the failure of the brake system. It is also very important that the orifice in the tubing adapter at the rear of the master cylinder of the brake coupler be a minimum of 1/16" (0.0625) or larger.
A brake lock-out mechanism will be necessary for backing up when using disc brakes with a hydraulic surge brake coupler. This is most often done with a reversing solenoid valve, which when connected into the back-up lite circuit of the tow vehicle will disable the trailer brakes, allowing the vehicle to back up.
Boat Trailer Brake Safety
If a manual lock-out pin is used to lock out the brakes during backing-up operations, it is critical that the lock-out pin be removed from the lock-out position during forward highway use, or the trailer brakes will not operate when needed.
Be sure that the surge brake coupler will compress and telescope forward during braking and towing operations. If the brake coupler will not pull out during towing operations, then pressure will be maintained on the disc brakes while towing and they will overheat during highway travel.
It is also essential that you confirm that the DOT required breakaway cable on the surge brake coupler is in the towing position and not in the emergency breakaway position while towing forward. If the breakaway cable is in the emergency breakaway position during highway travel, hydraulic pressure will be maintained on the trailer brakes and they will overheat and may fail.
Trailer Brake Controller
A Trailer Brake Controller (TBC) is usually an aftermarket installed device or module that serves as a great alternative for your run-of-the-mill boat trailer disc brake system, if you can afford it. It is mounted to the tow vehicle’s drivers side dashboard area that engages a trailer’s braking system proportional to the tow vehicle’s brake engagement when slowing down or coming to a halt. It’s fairly easy to convert from a surge-style brake to a the far superior electric brake.
A good TBC will have a +/- gain adjustment. The tow vehicle operator would set the gain as high as possible but without the trailer brakes locking-up after making a few test stops. The heavier the trailer, the higher the gain adjustment would be set and therefore the less chances of wheel lock-up.
A wide range of trailers contain trailer brakes (for example; larger boats trailers, horse trailers, covered utility trailers, travel trailers including small 10-foot and longer tent trailers and car carriers). Smaller trailers may not contain trailer brakes (for example; lawn service trailers and basic 4′x8′ utility trailers). It is highly recommended that if the total trailer weight is over a couple thousand pounds, the trailer needs to have some sort of braking system and the tow vehicle be equipped with a TBC.