With fishing seasons nearing, now’s the time to give some thought to the parts of boat trailers that cause the most problems: lights and wheel bearings.

Lights

The most common headache with boat trailers is the struggle to keep the lighting system in working order.

Corrosion and oxidation attack the weak links of the system — plugs, bulb terminals, splices — robbing them of solid connections. Take preventive measures by keeping the four-flat plugs and receptacles clean by giving them an occasional spray with penetrating oil, then with battery terminal spray, which is available at auto parts stores.

Another option is a thin coating of dielectric grease. While this grease is nonconductive, a thin coat won’t prevent a good connection between clean metal. It’s commonly used for marine-related applications.

Many tow vehicles used today feature a round blade-terminal receptacle, meaning an adapter is needed, creating more contacts. Be sure to service these as well.

Splices are vulnerable to corrosion. They are most common where the plug pigtail joins the main wiring and in hookups between individual lights and the wires that feed them.

Typically, crimp-on butt connectors are used to make these connections. These have a nasty habit of pulling apart as well as corroding.

When replacing butt connectors, buy the good ones from an electrical supply store. Butt connectors that feature a heat-shrink insulating sleeve are available, too. I’ve used these with success.

Bulb filaments break from vibration or they simply burn out. Typically, it’s a simple matter to disassemble a light to get at the bulb. Since there are many similar bulbs, take the bad one to the auto parts store and have the employee help with the replacement. When you’re sure it’s the right one, buy some spares. Dab the connectors with dielectric grease when you replace them.

Wheel Bearings

A bad wheel bearing can cause a major dilemma, especially when it’s not discovered until it damages the axle spindle, the part the bearings ride on.

Bearings rely on grease to prevent failure. Boat trailers present a challenge, since the wheels are regularly subjected to water during the launching process.

There are two common means of maintaining proper grease loads in wheel hubs. Some axles feature a grease fitting on the end of the spindle. To access the grease fitting, you remove the neoprene dust cap. Grease pumped into this fitting reaches the inside of the hub through holes drilled in the spindle, ones located to lubricate both the front and rear bearings.

The other system is of the “bearing buddy” design, in which the dust cap is replaced with a spring-loaded cartridge that is filled with grease. The cartridge acts as a reservoir, with the spring providing the force to load grease into the hub as needed.

I’ve only had three bearing breakdowns, and I’d say all were the result of water getting into the hub, which breaks down the grease.

For that reason I now keep two extra hubs for each of my two trailers. The hubs already have the bearings installed. Each spring, it’s a simple matter of popping off the tire, removing the hub and then replacing it with the spare.

The “old” hub then becomes the spare after it’s had new bearings installed.

While the dust cap (or bearing buddy) keeps water from entering the hub from the outside, a grease seal is used on the inside of the hub. When you are buying components to service the hub, make sure you get a double-lipped grease seal, which is designed to seal from both inside and out.

Standard grease seals are made only to keep the grease in the hub, not to prevent water from getting in from the outside.

Make a habit of inspecting the trailer wheels after you’ve launched the boat.

Once you’ve dropped your boat and parked the rig, give the trailer a shove with your foot to check for any side play.

Watch the tires in the mirror for any wobble as you back down the ramp. Keep your ears tuned for funky sounds back there.

Catch things early and it’s a simple matter of replacing the hub on site with a channel lock, punch and hammer.

Wait too long and the axle spindle will be toast, resulting in a tilt-bed service tow, a trip to the weld shop to have the spindle replaced or even a new axle.

Jeff Knapp is an outdoors columnist for the Butler Eagle.