Boat Trailer Bunks,
Installation and Adjustment

Boat trailer bunks need to be properly installed and maintained to provide proper support for your boat, and to allow for safe transport and easy launch and loading. There are two basic types of trailers, one that uses a series of rollers to support the entire weight of the boat, and a bunk style, which uses carpeted or padded supports. We will discuss the bunk trailer and how to properly adjust the bunks and other trailer components.

A bunk style trailer typically uses carpeted 2x4's or 2x6's to support the weight of the boat. Bunks need to be adjusted properly to prevent damage to the boat, and also to facilitate easy launching and loading. On a typical 2 bunk trailer, each bunk would be positioned one on each side, half way between the chine (outside edge of the boat) and the keel (center). If the boat has strakes along the bottom, then the bunks can be positioned against the outside edge of the strake to help guide the boat on the trailer when loading. Keep in mind that you do not want to position the bunks too far out from the center of the boat, as this will make it more difficult to center the boat when loading.

Be sure to adjust the height of both the front, and the rear bunk support, as well as the tilt from right to left, so that the bunk conforms to the bottom of the boat, allowing the weight to be distributed evenly. This will help prevent hull distortion over time, while also providing a more stable platform for the boat to sit upon.

Rollers are used on a bunk style trailer to help the boat roll on and off when loading or launching. It is very important that the rear rollers be adjusted so that they are NOT supporting the boat when it is completely on the trailer. The weight of the boat should be supported completely by the bunks, which distribute the weight evenly over a larger area. On "V" bottom boat, the rollers will support weight only when the boat starts to move backward when launching, or when the boat is coming onto the trailer while loading. Only the forward most roller or rollers which contact the keel of the boat, should bear any weight. Use the hand winch to pull the front of the boat securely against the bow stop, which is usually a "V" shaped roller or a "V" block, so the boat will not bounce up and down on the trailer.

Many trailers today are custom fitted to the boat, and require no adjustment. You should still periodically check the condition of the bunks and rollers, as well as all your trailer components including tires, rims, jacks, lights, winches, and tie downs, so that you can make it to and from the lake safely.