Hitch And Go
Break down your off-season trailer maintenance into these four simple parts so you won't be breaking down when boating season hits.
by Chris Caswell
February 1, 2004
Many skippers spend hours working on their boat, yet give only a cursory thought to the
trailer. Too often, this leads to a boating experience that isn't much fun.
A trailer may seem as complex to maintain as your family car, but if you break it down into
the various systems, you'll not only make the job easier, you'll simplify your maintenance. There
are four basic systems: the metal frame, the wheels, the wiring and the boat supports. Taken
individually, there's nothing mysterious about maintaining your trailer.
The Frame
The backbone for your trailer is the frame, which is usually welded and bent from structural
steel channel. You already know about steel and water - especially salt water. Your battle against
rust will never be won, so you need a good delaying campaign.
Assuming that your trailer started with a good undercoat and a thorough coating of paint,
your anti-rust efforts are likely to be directed toward dings from road gravel or that scratch you
made while loading the anchor. Keep a can of gloss white Rustoleum in a storage box on your trailer
and use it to touch up these spots as soon as you find them. By topcoating the bare metal before it
rusts, you can stave off those rusty stains in the future. Hosing your trailer off thoroughly with
fresh water after launching in salt water is good preventive medicine, too.
While you're giving your trailer an examination for dings, take a moment to look at the
welds, too. Hot gasses formed during the welding process can sometimes cause minute pinholes that
need to be covered with paint so they don't rust internally. Watch for fractures on or near the
welds, which can indicate a serious problem that needs rewelding, and perhaps the addition of
triangular gussets to spread the load more evenly.
The springs on most modern boat trailers use nylon insert bushings in axle springs, which
need little more than an occasional inspection for wear. If your trailer springs have grease
fittings at the forward spring mounts or at the rear spring shackles, a quick shot from a hand
grease gun every few trips will protect against frozen spring mounts.
Wheels
As is the case with most things nautical, the simplicity of maintaining your wheels and
bearings is inversely proportional to the amount of neglect they have received. If the bearings
have been woefully neglected, for example, they can freeze to the spindle and you'll need tools
such as gear pullers and cold chisels to get them free.
If you've take care to inspect and repack the bearings on a regular basis, then your chores
are short and simple.
The basic parts to a wheel and axle assembly consist of the spindles, which are attached to
each end of the trailer axle, the hubs that slip over the spindle and to which the tire rim is
bolted, and a pair of tapered roller bearings - inner and outer - that allow the hubs to spin
freely on the spindle. All of this is held in place by a single nut on the end of the spindle,
which in turn is prevented from unthreading by a cotter pin. To retain the lubricating grease, a
seal is used on the inner side of the hub, and a dust cap is placed over the outside.
The two keys to protecting the bearings from rust are to make sure that both seals are in
good condition (check for leaks on both sides) and keeping the bearings packed in grease. Many
trailers have specially enclosed bearings that either claim to be waterproof, or have fittings that
allow you to pump grease into the bearing area on a regular basis to displace water. These are
worth the investment, but you should still take the assembly apart every few thousand miles and
repack the bearings. At that time, you can inspect them for roughness caused by grit or rust, which
signals time to replace the bearings.
Trailer rims, which are run over curbs and immersed in salt water, are subjected to more
abuse than those on your car, so inspect them for dents and touch up the paint regularly.
Tires are usually overlooked. Check the capacity rating molded into the sidewall. If that
capacity, multiplied by the number of tires, doesn't exceed your boat/trailer package's weight,
you're in for trouble.
If you have a choice of tire sizes, pick the largest diameter available to reduce tire and
bearing wear at highway speeds. Invest in a pocket tire gauge, and use it regularly (with the tires
cold) to check your pressures, because even a few pounds difference can cause trailer sway.
Most states require brakes for loads over 3,000 pounds, so you'll probably have surge brakes
that don't require the tow car to be modified as with hydraulic or electric brakes. Surge brakes
vary from trailer to trailer, and because they are both tricky and crucial, leave the brake
adjustments and maintenance to a pro unless you're an experienced mechanic. When having your brakes
serviced, be sure to have the breakaway chain (which sets the brakes if the hitch fails) tested.
Wiring
The wiring harness on your trailer can take a real beating because water and
electricity just don't mix. If your trailer lights aren't waterproof, then they should be
removable. Immersing non-waterproof lights is an invitation to shorts and malfunctions.
Start at the tow car end of your wiring harness, and trace it carefully, checking for wiring
that has turned brittle with age or heat or that has been abraded by dragging as you cross a
driveway. Trying to patch up sections of bare wire with electrical tape is a stop-gap measure at
best: Replace that section with new wiring of the proper size (and use the right color wiring; more
on that later). As you trace the wiring, check for connections that are loose or corroded, and make
a note to replace them as well. Last, track down the ground wire and remove the screw or bolt that
holds it to the frame. You may find that the attachment is so rusty or corroded that it no longer
grounds anything. Once you've assured yourself the basic wiring is sound, you can move to the light
fixtures.
If you have clearance lights along the side of the trailer, unscrew the plastic lenses and
inspect the bulbs. There is likely to be corrosion in the sockets since these bulbs are rarely
replaced, so spray the sockets with a corrosion inhibitor and replace the bulb.
If the tail lights are removable, check the plug-in connection for corrosion. If the plugs
are greenish and coarse textured, sand them lightly with fine sandpaper, swab the sockets with
sandpaper wrapped around a Q-Tip stem, and spray both with more corrosion inhibitor. If you've
removed the tail lights with every launching, they're probably good. If not, give the sockets and
wiring the same refurbishing.
Waterproof tail lights rely on a gasket to keep the water out, but to inspect it, you must
unscrew the lens assembly, being careful not to tear the gasket, which may have adhered to the
surfaces. If the gasket has turned brittle, buy a replacement or cut one from a sheet of rubber
gasket material at an auto parts store.
When replacing wiring (or trying to sort out the wiring on an old trailer), remember the
color for the left turn signal and brakes is yellow, the right turn signal and brakes are green,
and the tail lights (and clearance lights and license plate light) have brown wiring. White is the
ground, and it's important to have a separate ground wire going to your tow car. Many trailers use
the trailer ball hitch as a ground, but with water and dirt on it, it's a poor ground.
Boat Supports
Rollers are a contradiction in terms because, in the case of trailers, they usually don't.
Most of the hard rubber rollers on trailers need regular lubrication, and squirting them with
bearing grease occasionally can't hurt.
The bunks on a trailer are usually carpeted and, after some use, the carpet starts getting
stiff. When the boat is off the trailer, hose the carpet to get rid of the salt crystals, sand and
other junk that can scratch your hull. Inspect the carpeting often, both for signs of wear and for
loose staples, which can pull out of the bunk and gouge your hull. When the carpet starts to wear
or gets too stiff, replace it with remnants from a local carpet store (try to use synthetics like
nylon or polyester).
With regular maintenance, there won't be any surprises when you hook up the trailer. The
lights will work, it will tow smoothly, and while it may not sparkle, it won't be a rust bucket
either.