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Trailer Brakes: Give Me A Brake

When was the last time you thought about your trailer brakes? Was it the last time you used your boat?

Brake wheel

A properly installed and maintained stainless disc brake. Note the non-metallic flexible hydraulic line, further protection against rust and corrosion.

If you're like most people you don't give your trailer brakes a second thought, until you have a problem. I recently took a walk through the parking lot of my local marina on a busy afternoon and was surprised by what I found. Half of all the trailers in the lot were in violation of state law by having damaged, undersized, or non-existent brakes. The laws vary from state to state, but almost all have minimum requirements, and some municipalities are cracking down. Most states begin requiring brakes on trailer weights in the 2,000-4,000 pound range; although some, like North Dakota, require all trailers to have brakes, while Massachusetts has virtually no laws governing pleasure boat trailers.

So now that you know you need them, what are your choices? Essentially, trailer brakes come in two flavors: disc and drum. Choosing the type that's right for you depends on your boat size, environment, and boating habits. We'll outline the pros and cons of each so you can decide what's best for your situation.

Drum Brakes

Drum brakes used to be the old standard. The main advantage to this style is cost. They're less expensive to install and cheaper to maintain. Also, they're somewhat easier to replace, which is nice because you'll have to do it two or three times more often than discs. The disadvantage to drums is longevity. The inherent design of a brake drum allows several inches of water to pool inside the drum after it's been submerged, and it will remain there until it eventually evaporates out. If this is salt or brackish water, the corrosive effects will be worse than if it's fresh water. Flush kits are available and recommended if you're backing your trailer into salt water, and will extend the life of your brakes. But remember that the fresh water from your garden hose will still collect and sit in the drum. Drums also require manual adjustment every 3,000-5,000 miles.

Brake drum

A typical brake drum. Note the number of moving parts, each one a potential point of failure.

Disc Brakes

Disc brakes are available in a variety of materials: standard automotive, E-coating, silver cadmium, and stainless steel, and the prices vary accordingly. Stainless steel will outlast all the other materials but aren't entirely immune to corrosion. Disc brakes have only one moving part, the caliper, as opposed to nine to 12 moving parts in a drum brake. Fewer moving parts equate to fewer potential failure points and a longer overall life span. Friction pads and calipers are readily accessible for inspection, cleaning, and maintenance. Disc brakes are self-adjusting whereas drum brakes require periodic manual adjustment. The advantage of being self-adjusting other than the obvious time/maintenance factor is that they offer more even and consistent braking on each axle resulting in a smoother operation. Disc brakes are also less likely than drums to be affected by rust, dirt, or corrosion. The disadvantage to disc brakes is their relative initial cost; they can be twice as much as drum brakes to install.


Regardless of the type with which your trailer is equipped, the most important thing is to keep the brakes clean. If you're using your boat in salt water your brakes should be rinsed with fresh water after each use in the same way that you would flush your engine. Some marinas supply fresh-water wash-down facilities, and these should be taken advantage of every time the trailer comes out of the water. Salt water reacts quickly with metal and will begin deteriorating your trailer and all of its components in the parking lot while you're out on the water. If possible, hose down the trailer, brakes, hoses, and so on with fresh water immediately after launching your boat. Disc brakes are easier to rinse because all the parts are exposed. If your marina doesn't supply fresh-water wash-down facilities, a pump sprayer, like the kind used to spray garden chemicals, can be filled at home and brought to the boat ramp.

Some companies offer spray kits, such as Starbrite's Trailer Spa, which consists of a network of hoses that attach permanently to the trailer. A garden hose attached to a single inlet on the trailer distributes water to a number of spray heads mounted to strategically rinse brakes, springs, and other vulnerable areas. There are also some commercially available products that will not only break down the residual salt, but also leave a protective film against further corrosion. Fresh water is less corrosive than salt water but dirt and sediment can still build up on drums and rotors causing premature deterioration; they should be rinsed after each use.

Visual inspection of your brakes should be a routine part of your boating experience. While hosing your brakes down at the end of the day check for worn parts, rust, and corrosion. Older style brake lines were often constructed from galvanized tubing and in many cases ran internally through the frame of the trailer. Areas where the brake lines are exposed may be vulnerable to rust, which may eventually compromise the integrity of the lines causing hydraulic fluid to leak out of the system. No brake fluid means no brakes. Newer brake lines are often constructed of non-metallic DOT-compliant flexible rubber hose. While these hoses are impervious to rust and corrosion, they should be routinely inspected at any point where they contact the steel frame of the trailer to insure that friction against the frame is not wearing a hole in the tubing. Rubber tubing is also susceptible to dry rot if exposed to salt water and sun and should be rinsed after each use. Stainless steel hydraulic lines offer the greatest longevity but are considerably more expensive than galvanized or rubber tubing. Plus, stainless tubing cannot be easily cut and flared by a DIY'er and needs to be purchased in pre-measured lengths or installed by a professional. Hydraulic lines are typically attached to the trailer frame using tie wraps and/or clips attached to the trailer and should be replaced if damaged or missing.

Warning Signs

Trailer brakes differ from automotive brakes in two ways. First, they're not equipped with audible sensors to warn you when pads and rotors become worn. Second, you drive your car or truck every day, which keeps your pads and rotors clean. If you're like most recreational boaters you submerge your trailer in water on the weekend, then let it sit for a week or two — ample time for a thin layer of rust or corrosion to build up. This may cause some squeaking for the first couple of brake applications until the film is worn away, which is normal. What isn't normal is excessive noise, which can occur when the brake lining is worn down to bare metal. Brakes that grab or lock up can indicate a failure in one or more of the moving parts or, in the case of a trailer that's sat unmaintained for a long period of time, enough rust may have built up between a caliper and rotor to cause irreparable damage. Another visual cue: Look for uneven tread wear on your trailer tires — another sign that a brake is dragging on a particular axle.

Brake caliper

Even stainless steel is not entirely immune to corrosion, and requires regular inspection and cleaning. The hydraulic fitting on this caliper is rusted to the point that fluid can no longer pass through it, rendering it useless.

So, What Do I Need?

If you're towing a bass boat or a small bow rider with a gross trailer weight of less than 3,000 pounds and launching in fresh water, drum brakes may be perfect for you. In fact, drum brakes appear to offer greater stopping power for loads under 3,000 pounds. In salt water or towing above 3,000 pounds, consider disc brakes. A point that bears repeating is that almost every state has laws governing trailer brakes, and it's important to know what the laws are in all of the states you use your boat. Keep in mind that if you take your boat with you on vacation and cross state lines, what's legal in one state may not be in another. Ultimately, the goal is not only to get your boat to the water, but to be able to stop when you get there.

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Scott Henze

Contributor, BoatUS Magazine

Award-winning BoatUS Magazine is the official publication of Boat Owners Association of The United States. The magazine provides boating skills, DIY maintenance, safety, news and more from top experts.