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All About Boat Trailers - One man's perspective...

When we shop for boats, we look critically at the boat. We scrutinize its condition and whether it will meet our needs. On the other hand we probably don’t pay as much attention to the trailer as we should, which is interesting given the ratio of how much time the boat spends on it compared with the amount of time it spends on the water.

Imagine the havoc it would wreak if you dipped the back of your truck in water as often as you do your boat trailer.

If what you’re carrying is important — and a boat certainly counts — you should spend some timing thinking about what kind of trailer you’ll need. Like so many other products, the quality of trailers varies widely, and if you look closely in all the right places, you can spot the differences. As simple as it sounds, a decent rule of thumb when trailer shopping is, “you get what you pay for.” Let’s look at the subject in terms of size and type, safety, and maintenance.

First is size. Of course, the boat determines the size of the trailer you need. Dual-axle trailers are nice, but they have twice the number of tires that eventually need to be replaced, and I don’t know anyone who relishes buying trailer tires. So, unless your boat is at least 20 or so feet or longer, or inordinately heavy, or unless you do lots of long-distance trips with your boat, you can economize by going with a single-axle trailer. It just doesn’t look as cool as the Jones’ trailer. Fight the urge. If you don’t need one, don’t bother. It’s cheaper to operate long-term.

However, if you do take long trips, a dual-axle trailer is more stable at highway speeds, and if you get a flat on the freeway, dual axles offer a measure of safety you don’t get with a single-axle trailer. Dual axles spread the load more effectively over the four-tire contact patches. Dual-axle trailers also can be equipped with brakes on both axles, which great decreases stopping distance and enhances safety.

Unless your boat is longer than 20 feet, inordinately heavy, or you regularly take it on long road trips, you don’t really need a dual-axle trailer. A single-axle trailer is cheaper to operate and maintain. Photo: C.E. Smith.

That, of course, necessitates that the boat be tied down tight. I towed boats for a long time without the stern being attached to the trailer, but now I almost insist on it, for the same reasons we wear seat belts. It’s only slightly discernible, but you really can feel the difference from behind the wheel. You hear one thump when going over bumps instead of two. The boat and trailer move as one, and if you ever get into a situation that involves a panic stop, or worse, a collision, there’s one less moving object in play.

If you don’t need a new trailer, but yours doesn’t have a way to tie down the stern, you can buy straps from West Marine or another such retailer. It also points up the need for a good bow attachment point. That means a sound crank mechanism, roller, strap, and bow eye.

How to Choose

When it comes to the type of trailer you want, let’s just outline what types are available and you can figure out for yourself what you want. I’ve written about this before, but focused a bit more on axle types and light packages, and before that on brake systems.

Unless you know something I don’t, there are two materials from which to build a boat trailer: steel and aluminum. Obviously steel is usually stronger, but because it is a ferrous metal, it will rust. Aluminum corrodes, but it won’t rust. Raw steel is a cheaper material than aluminum, but that doesn’t mean all steel trailers are cheaper than their aluminum counterparts.

For longer distance trips and for larger boats, a dual-axle trailer is the safer choice. Photo: LoadRite.

As a general rule, if you do all of your boating in fresh water, you can more easily get away with a steel trailer. It will rust if you leave scratches in the paint unattended, but a decent steel trailer should last the life of your boat if you maintain it properly.

Conversely, if you do your boating on the ocean or the Intracoastal Waterway, you should opt for an aluminum trailer. They’re not as pretty as a steel trailer with paint that matches your boat and tow rig—think I-beam aesthetics—but as we mentioned earlier, they don’t rust.

You also need to choose the trailer’s support system: rollers or bunks. Rollers tend to make loading and offloading a bit easier, but they don’t cradle a hull like bunks do. Four Winns boat company, which makes its own trailers, engineers them so that the bunks align with the linear stringers to provide support in places where the boat is strongest.

Also, rollers do not distribute the boat’s weight the way bunks do. Boats that sit unused for a long time on roller trailers (as they often do in winter) can develop a “hook” in the running surface at the transom, or other imperfections. For the amount of money you spend buying a boat that goes fast, and on modifications to make it go faster, the last thing you need is a tweaked bottom. Have we talked you into bunks yet?

Rollers make boats easier to load and launch, but for long-term storage, longitudinal bunks will support a boat more evenly. The biggest negative with rollers is maintenance and failure. They are costly to maintain where bunks require almost no maintenance.

For suspensions, two types of systems are used, and each has a record of reliability. Torsion-bar systems, in which a torsion bar runs inside the axle, allow for a lower ride height. The drawback is that the system is more costly than leaf springs but they do last approximately twice as long.

Leaf springs have been used for centuries, and they are solid performers. Be sure to get a setup that can handle the weight of your boat. A lot of manufacturers put three-leaf springs on trailers, but you can find better models with five-leaf springs, which are stronger and less likely to fail over time.

While you’re crouched beneath the trailer counting leaves, also make note of the trailer’s hardware. Does it have stainless Bearing Buddy caps or chintzy stamped steel caps that leak water into your bearings? Or does it have the really slick industrial, sealed oil-bath bearings, such as those that come on Extreme Custom Trailers. How thick is the metal? Are the welds neat or do they look like a third-grader laid them? Quality is important.

Pay attention to the thickness of the metal used in the trailer’s main construction, including the cross-members, and compare trailer-to-trailer. A lot of manufacturers are using thin stuff simply because it’s cheaper. This logic applies to aluminum trailers, too. Not only should you look at the thickness of the aluminum, but also at the height and the width of the supports. Taller, thicker I-beams are stronger.

It’s also important to inspect a trailer’s hardware. Lots of manufacturers used galvanized fasteners. Sure, they won’t rust anytime soon, but galvanized fasteners can cause corrosion between dissimilar metals. You want stainless steel, always.


In terms of maintenance, the three most critical items on a trailer are wheel bearings, wheel bearings and wheel bearings. Why? Because bad wheel bearings will keep you from getting to the lake. They stand between you and precious time on the water. Tires are critical, too, but you generally have a spare, so a flat or blowout can fixed by the roadside. Bearings? Not likely.

Wheel bearings are the most critical maintenance item on a boat trailer because they can leave you stranded by the roadside and keep you off the water. Service your bearings with fresh grease before each boating season and replace them as necessary.

Grease is actually about 90-percent oil. The other 10 percent is comprised of thickening agents, performance additives, oxidation inhibitors, components to help prevent wear, and rust-inhibiting compounds. Grease works by releasing its oil, so in a bearing application you get a little bit of oil released by the grease, and that oil is what lubricates the balls or rollers in a bearing. As oil is released, you have a reduction in oil content, and you only have to reduce that oil content by about 15 to 20 percent until it reaches a point at which point it no longer lubricates. Service your bearings with fresh grease before each boating season and replace them as necessary.

The rest of a trailer can be maintained by “keeping an eye on things.” Inspect bunk carpeting when the boat is in the water. It it’s torn, replace it. Check your brakes and lights each time you go out. Lubricate the coupler and the tongue jack a couple of times per season. Inspect your bow strap and roller mechanisms each time you use the trailer.

By keeping an eye on things all the time, you don’t have to set aside a valuable weekend day for trailer maintenance. You can spend that time with your trailer parked and your boat on the water — where it should be.

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