How to Protect Boat Trailer from Salt Water

Remove the saltwater from your boat trailer after a day of fishing.

Saltproof Your Trailer
For a nominal cost, you can construct an effective rig to rinse the underside of your trailer using a garden hose, a Y valve, two lawn sprinklers and a PVC pipe.SWS Staff

Florida angler Joe Bak has a unique way of shedding salt water from his trailer after a day’s fishing in the nearby Indian River Lagoon. On the way home, he makes a quick stop at a convenient ramp on one of the area’s many freshwater lakes and backs his rig in as far as necessary to completely submerge all components of the trailer that were exposed to the salt and, at the same time, deep enough to provide sufficient cooling water for the engine. He runs the outboard for 10 to 15 minutes to flush the cooling system, removes the transom drain plug and turns on the bilge pump. This serves to rinse all of the salt water out of the bilges. Once he has completed these tasks, all he has left to do is drive home, wash down the boat and put it away. That’s one unique technique for boat trailer rust prevention.

Personally, I don't have a convenient freshwater ramp on my way home from salt water, so by necessity I use a different but just as effective approach. I take two lawn sprinklers rigged on the ends of a piece of PVC pipe and slide them underneath the trailer to cleanse it of salt water. The PVC pipe is just long enough to provide a slight overlap in the sprinkler's spray patterns. I use a Y valve to split the water from the faucet to two hoses so that I can flush the outboard while the sprinklers thoroughly soak the part of the trailer that came into contact with salt water at the ramp. Always keep in mind that if there are any weaknesses in your trailer, salt water will find them sooner or later (usually sooner). The best boat trailers for saltwater are those that are cleaned every trip with fresh water. Anything that can rust, rot or corrode will do so in surprisingly little time in saltwater environments, especially if you must submerge the trailer in order to launch the boat. If you fail to keep up with basic trailer maintenance, you are asking for problems.

Bearings and Springs Boat Trailer Maintenance

Florida resident and trailer expert Kevin Charlton (Strictly Trailers; 305-665-6313) says the trailer components most vulnerable to saltwater damage are wheel bearings, leaf springs and anything else not made of aluminum or stainless steel. In fact, most on-road trailer mishaps occur because of a wheel bearing failure due to the intrusion of salt water into the hubs while launching or recovering the boat.

There are two proven ways to prevent wheel bearing failure. The first is to service them annually. This entails removing the bearings and completely cleaning out the hubs before re-greasing and reassembling. Also replace the bearing seals with new ones; the old seals should never be reused. The second way is a bit easier and far less messy. Simply replace each hub every year with a new one that is pre-assembled (complete with grease and seals). You can even have the old hubs cleaned and re-greased (with new bearing seals) by a service station and recycle them onto the trailer the following year. In the meantime, you should carry at least one hub that has fresh grease and all-new internal components in place aboard the tow vehicle in case of an emergency.

As for the springs, by far the most saltwater resistant are the torsion variety. But if you have leaf springs, you can make them last at least a few years longer if you recoat them as often as necessary with a thick lubricating spray such as CorrosionX HD. A good coating will last for many trips (typically six months or more) before it begins to wash off. The rest of the trailer, especially nuts, bolts and other fasteners, should be sprayed regularly with a moisture-displacing lubricant such as WD-40 or CorrosionX. I buy WD-40 in a gallon can at Home Depot for about $15, and I use a hand spray bottle that I bought there to dispense the WD-40.

The most convenient time to get the WD-40 to those hard-to-reach places is at the end of the day just before you load the boat back on the trailer. The trailer is dry by then, and the lube will displace the salt water out of the cracks and crevices. Even though the trailer will get wet again when you reload the boat, the WD-40 has already started doing its job. I do this every three or four trips because this way it only takes a few minutes to hit those critical spots.

Frames and Fasteners Boat Trailer Maintenance

When it comes to trailer frames, aluminum definitely lasts longer than the best galvanized steel. However, if you keep salt water off the galvanized metal with regular washings and periodic lubrication of rust-prone areas, it will still last years longer than otherwise. I replaced the most vulnerable fasteners on my last galvanized trailer with stainless steel long before they became too rusty. If there are rust-prone steel fasteners and other components on the trailer for which there is no stainless-steel equivalent, use a paintbrush to cover them with a thick layer of waterproof grease. A good coating will last several years.

Coating galvanized wheel rims with grease is way too messy for me, but a thorough washdown with soapy water at the end of the day removes the salt well enough to keep the rust at bay for many years. I use dishwashing liquid in one of those hose-attachment spray rigs typically used for dispensing pesticides, and it works for the entire boat, inside and out.

Another good thing to do from time to time is to remove the lug nuts, grease the threads and replace them with stainless-steel acorn nuts.

All of these procedures are really easy and require very little time and effort. If you make them a regular part of your boat trailering routine, you will be handsomely rewarded in the long run with a boat trailer that limits the effects of salt water and rust.