I was actually sitting on my front porch, working on the list of five boat-trailering tips to offer you in this column, when the sound of aluminum clattering in pavement caused me to look down the block. There I saw a truck accelerating across the intersection, pulling an empty boat trailer. The boat was resting in the street. “Boat falls off trailer” is not a common problem, but it illustrates that there are many, many ways things can go wrong when a boat is being transported on wheels. In fact, I could write a book. But for today, let’s stick to these five issues that, in my experience, most frequently ruin the day of a trailer-boater.
1. Low Air Pressure is the frequent cause of trailer tire failures, and is especially prevalent in the spring. Your tires will leak away two or three pounds of air pressure a month on their own. So if your trailer has been sitting all winter, by Memorial Day your tires could be significantly low. Under-inflated tires get hot at highway speeds, and eventually fall apart – an inconvenience at least but a potentially deadly situation at worst.
Check out this column on my neighbor’s low-tire-pressure nightmare for more details. You want to keep your tires filled to the maximum air pressure as indicated on the sidewalls, which is usually about 50 psi. Fully inflated tires will also improve your towing fuel mileage.
2. Failed Wheel Bearings can lead to the wheel coming off the trailer. Because the bearings are often submerged during launch and retrieval, boat trailers are usually equipped with pressurized hubs, often referred to as Bearing Buddies, which is a trademark for a popular brand. These devices hold grease under pressure in the hub, which keeps water from contaminating the bearing. You want to keep these hubs lubed per the manufacturer’s instructions. Once or twice a season, I like to jack each trailer wheel off the ground and try to wiggle the wheel back and forth to make sure the bearing is still tight. I got a new trailer last year, and in reading the owner’s manual discovered that I should re-tighten the axle spindle nuts after towing about 100 miles. I am always suspect of the wheel bearings on a used trailer, and have an auto repair shop inspect the bearings and brakes. While on the road, I check my bearings at every gas stop by feeling the hubs to make sure they are not getting very hot. I have replaced a failed trailer wheel bearing in a parking lot, and now carry a spare bearing assembly and tools on long trips.
3. Leaving home with No Spare Tire seems like an obvious mistake, but I frequently see forlorn trailer boats abandoned by the side of the road, left perched on one wheel. This is a sign of spring here in Wisconsin, because the owner did not check his or her tire pressure (see Tip #1). Now they have a flat and no spare. Or no way to jack up the trailer to change the wheel. Or no wrench for the lug nuts. They have to leave the boat and drive on for tools or a new tire. And while they are gone, the prop and fish finder are stolen. So…you want to be ready to change a flat trailer tire. Carry a spare inflated to the correct pressure. Make sure your tow-vehicle jack can be used to jack up the trailer, or better yet carry a bottle jack rated to lift your rig. Try it at home to make sure it will fit under the axle. If the lug wrench in your tow vehicle is not the right size for the trailer lug nuts or bolts, you’ll need the correct-size tool. I’ve started carrying a battery-powered impact wrench to do this job. Once a season put some grease on the lug nuts or bolts so they don’t get bound up with corrosion.
4. High-balling is the term used by trailer manufacturers to describe a mistake I have made twice over the years. I set the trailer coupler on the hitch and assumed it had dropped over the ball, and even flipped down the coupler latch. But the coupler was in fact just resting on top of the ball, probably because the mechanism inside the coupler was a little corroded and not moving freely. In one case, my safety chains arrested the trailer when the coupler lifted off the ball at a stop sign. In the other, I cheated death again and drove more than 200 miles without realizing my mistake. Now I double-check the hitch every time. On smaller trailers, you can lift the trailer tongue to make sure it’s tight on the ball. On bigger trailers, bend down to get down a hitch-level view of the situation. Or screw your trailer jack back up after latching the coupler to make sure it’s tight on the ball. And hit the inside of the coupler with some spray lube once in awhile.
5. I have spent untold hours trouble-shooting Trailer Lights, which give boaters fits because lights and water, especially salt water, are not compatible. New trailers have modern sealed connectors and LED lamps and are less problem-prone than older rigs, but not perfect. You want to check that all of your trailer lights are working before every trip. I find this is a good job for a trustworthy child, who feels very important standing behind the trailer while you test the turn signals. If just one of the lights is not working, you’ve got either a bad bulb, a corroded bulb socket, or a loose or shorted wire to that lamp. I start by using a test lamp to see if I’ve got juice to the socket. If the test lamp glows, it’s a bad bulb or a bad connection in the socket. You can use a pencil eraser to clean corrosion off the contacts within the socket. Install a new bulb with a dab of dielectric grease. If all of the lights are not working, I start by checking the ground wire (the white one) between the trailer and the tow vehicle. Some trailers are grounded through the hitch, and I’ve seen a rusty hitch ball or receiver prevent that ground from working until a few miles of driving wears through the corrosion. For this reason, I prefer a separate ground wire. Check the wire to make sure it’s securely attached to the trailer, usually through a bolt or screw to the trailer frame, and that it’s got a clean connection under that bolt. Corrosion in the wiring harness plug is another cause of general light failure. Look for green goop in there, which you can try to clean up with a shot of WD-40 and a toothbrush. I keep my plug coated with dielectric grease to protect it from salt water and winter road salt.
If these obvious solutions do not get your trailer illuminated, start trouble-shooting at the harness plug on the tow vehicle, using a test lamp. If there’s no juice making it to the plug, you know the problem is in the wiring on the vehicle. Otherwise, start working your way back on the trailer, checking for a broken wire or a wire that has worn through its insulation and is shorting on the trailer. Good luck. In my trailer tool bag I carry spare bulbs, dielectric grease, a length of multi-strand trailer wire with a plug, and some wire splices, all to make road-side repairs.
Editor’s Note: Charles Plueddeman, our Outboard and Trailer Expert, is the editor at large for Boating, the nation’s largest recreational boating magazine