Do It Yourself Boat Trailer Tongue Extension

Boatload of apples
Aaron McCoy / Getty Images

While the rare trailer comes with a built-in, slide-out tongue extension, many boat trailers are simply too short for boaters to easily launch and retrieve their boats at shallow ramps without driving at least the rear wheels into the water—or worse. This is especially true for sailboats, which typically sit higher on the trailer. And amazingly, only one company can be found online making a bolt-on kit, ExtendaHitch, but it's rather expensive and may require other trailer modifications, such as sawing off the "skid leg" typically found beneath the trailer's tongue.

You could take your trailer to a welding shop to have the receiver for a removable extension welded in place, but that costs more too and is inconvenient.

Instead, you can build your own removable extension with simple tools and readily available parts that bolt together. The 6-foot extension shown here along with its own hitch coupler and the receiver hardware attached to the trailer cost only $120 for parts and took about an hour to assemble. (Important: An extension like this is only for use at the ramp, NOT for towing.)

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The Receiver Tube Mounted on the Tongue


The extension itself is a heavy steel square tube of appropriate size for the trailer. The one shown here is 2 by 2 inches square (outer dimension) of steel a quarter inch thick and 8 feet long, providing a little more than 6 feet of extension. If you can't find heavy steel square tubing like this locally, you can order it online as low as about $75 for this length. On the vehicle end of the extension is mounted a standard hitch coupler, available in different bar sizes and for different size trailer balls.

The other end of the steel extension tube slides into the steel receiver tube that is mounted on the trailer tongue—this receiver is just like the receiver piece on many trailer hitch class 2 or 3 receivers mounted on vehicles. It comes with a half-inch hole in which you place a standard trailer hitch pin like the one shown (after drilling a hole in your extension tube to match).

You may have to get creative with where and how you mount the receiver (available in 12- and 18-inch lengths) on top of or below the trailer tongue. (You don't want it to mount if on the side, normally, because the greatest torque forces are vertical, and a side-mount could twist free or distort under stress.) In this example, the owner mounted the receiver above the tongue to avoid having to remove the triangular skid leg under the tongue. The spacers are needed to raise the receiver such that the extension clears the latch on top of the original trailer coupler. These spacers were scrap steel—very heavy rectangular tube cross-sections. Hardware-store brackets were used to bolt the receiver in place.

Can you spot the flaw in this arrangement?

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A Heavier Receiver Mount


The previous photo showed the receiver mounted with 3/8-inch bolts through clamp pieces from a U bolt— the heaviest off-the-shelf clamps from the local big-box hardware store. An engineer who was consulted was concerned what would happen with any twisting or sideways force on that mounting, so the boat owner decided to beef up the mount as shown here. Quarter-inch steel bar was cut and drilled to make the clamp pieces, secured with 1/2-inch galvanized bolts. The original two clamps were kept for added strength but repositioned. For straight in-and-out trailer use at the ramp, this arrangement has proved more than strong enough for this owner's boat under 2000 lbs, though of course it should not be used for trailering the boat more than the short distance up and down the ramp.

If you have a larger boat or want an extension as strong as can be, you can have the receiver welded to the trailer in an appropriate place.

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Welded Receiver


In this trailer, there was not a convenient place to mount the receiver on the trailer's tongue, so the owner had it welded farther back at the front of the trailer's frame. This required a longer extension tube to achieve the desired extension, but the long extension piece is easily stowed along the bottom of the trailer as shown here. In principle, this works just the same as the bolted-on version.

A tongue extension is easy to use and makes launch and retrieval much easier. To launch, simply back the trailer to the head of the ramp at a level point, aligned so that you will go straight back. Chock the trailer's wheels and uncouple it from your hitch, pull forward and slip the extension bar in place, pin it, and hitch the extended coupler to your vehicle and back it in.

Ultimately this is a much more controlled launch than the alternative chain or rope/webbing some boaters use to let an unhitched trailer roll down the ramp away from the vehicle. The problem is that the tongue of the trailer must be held up, requiring the use of a wheeled tongue jack or other wheels once the trailer is unhitched. Wheeled tongue jacks are not designed for the loads involved and seldom last long. Some boaters go to the trouble to mount other, large wheels to support the tongue and then use a chain extender to let the trailer roll down and to haul it back up, but the chain approach doesn't offer the same control—and ultimately costs as much as or more than the simple tongue extension you can craft yourself.