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Boat Trailers Are Not to be Ignored

Date Published: January 5, 2002

Boat Trailers Are Not to be Ignored

Rob McCarter

Fisheries Aide
District VI, Enterprise, Alabama


One of the most commonly overlooked, but probably most important, pieces of boating equipment is the boat trailer. Without the trailer, the boat would not make it to the water. Trailers consist of a frame, axles, bearings, hubs, tires, runners, rollers, winch, and lights. Some boat trailers are equipped with trailer brakes. Each piece of the trailer is important and demands periodic inspections.

Most modern boat trailers are built from galvanized steel or aluminum to prevent rusting. Some older trailers were made from mild steel and had to be painted to prevent rust. Regardless of the material used, the frame needs to be inspected for cracked joints or rusted pits in the metal. If welding is required to repair a trailer, a qualified welder should be utilized. Visual inspections of the axles and springs need to be made as well.

Pictures taken by Billy Pope
Marine Police mechanic Brady Lindsey sprays the spring and shackle assembly with lubricant.

The bearings and hubs are the most problematic parts of the boat trailer. They are packed with grease to reduce friction. Tremendous heat builds up in the bearings at highway speeds, which results in grease breakdown. Water from repeated submersions will also flush grease from the bearings. As grease breaks down, heat is increased resulting in the bearing locking to the spindle, ruining the hub, and possibly the axle. To prevent bearing lock-up, bearings need to stay full of grease. The easiest way to keep bearings packed is the use of buddy bearings. Buddy bearings replace the dust cap on the outer end of the hub and are equipped with a grease fitting. The fitting allows grease to be inserted into the hub with a grease gun. One or two shots of grease before each use can prevent an expensive hub or axle replacement.

Pictures taken by Billy Pope
Marine Police mechanic Patrick Mind pumps grease into the bearing buddy on this boat trailer.

If buddy bearings are not used, bearings need to be repacked each year. Repacking the bearings is performed by raising the trailer with a jack, removing the tire, dust cap, cotter pin, nut, washer and outer bearing. After removing these parts, the hub will slide off the spindle. The inner bearing will stay inside the hub behind the grease seal. A brass drift should be used to knock the seal out of the hub. Brass will not mar the bearing races. Clean the bearings, hub, and other parts in solvent and inspect each piece. Check the bearing races inside the hub to make certain they do not spin inside the hub. If the races spin, the hub is worn and needs replacing. Inspect the bearings for pits or hot spots and replace if necessary. Repack the bearings with factory specified boat trailer grease. Replace inner grease seals each time bearings are repacked. Reinstall inner bearing and seal into hub with a generous amount of grease. Next, replace outer bearing, washer, nut, and a new cotter pin. When tightening, snug the nut down until resistance is barely felt. Turn the hub on the spindle a couple of revolutions to seat the bearings. Then, loosen the nut and re-tighten until a slight resistance is felt in the bearing. Finally replace cotter pin and reinstall dust cover. The packing procedure needs to be followed, even if buddy bearings are used, just not as often.

Tires need to be inspected for tread wear and separation before each use. They need to be properly inflated, including the spare. Periodically check the torque on the lug nuts as well. Boat trailers equipped with trailer brakes need to be monitored for brake shoe wear. Make sure everything inside the drum remains free. Trailers are submerged in water repeatedly and may rust or lock-up inside the drum. Replace any worn or needed parts.

Other aspects of the trailer that require attention are the runners and rollers. Check these for breaks or cracks and, if necessary, replace with new equipment. Broken rollers or runners can cause problems launching and loading the boat and may cause damage to the hull.

Pictures taken by Billy Pope   Pictures taken by Billy Pope

Always keep the winch in proper working order. Pay close attention to the winch strap or cable. If the strap or the cable is worn or frayed, replace it. Worn or frayed cables and straps can break causing injury or damage.

The final step in trailer maintenance is checking all running and brake lights. Make sure all bulbs are burning. Replace blown bulbs immediately. Blown bulbs propose a safety risk on the highway. Most trailer light assemblies are not water tight, so always unplug trailer lights before launching or loading. Bulbs get hot when the brakes are applied, and if they are suddenly cooled by water, a blown bulb may occur. Unplugging the pigtail can save the brake light bulbs. Upon inspection, if no lights burn, check wiring and ground on trailer with a test light to find the problem and repair it.

Pictures taken by Billy Pope   Pictures taken by Billy Pope
Marine Police mechanic Brady Lindsey test the running lights on a boat trailer.

Boat trailer maintenance is very important and cannot be overlooked. Spending a little time to perform routine boat trailer maintenance can prevent leaving the boat and trailer by the roadside while trying to find replacement parts miles away.

Boat Motor Maintenance

Pictures taken by Billy Pope

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