How Do Boat Trailer Guide-Ons Work?

How Do Boat Trailer Guide-Ons Work?

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After a day of boating it's usually time to put the boat on the trailer and head home. Depending on the conditions, loading a boat on a trailer can be a difficult task. As the front of the boat is put on the trailer, the rear of the boat can swing in either direction, making it hard to center the boat on the trailer. Trailer guide-ons are aftermarket additions to a boat trailer, that keep the boat steady while loading.


Trailer guide-ons attach to each side of a trailer. Guide-ons are normally put towards the rear of the trailer but can be mounted in other locations. To load the boat with guide-ons one person backs the trailer into the water. Another person drives the boat onto the trailer. The front of the boat is then attached to a rope that pulls the boat to the front of the trailer using a winch. The guide-ons keep the boat centered on the trailer as it is being cranked forward.


There are two main types of guide-ons. The post guide-on is a single vertical metal or PVC post attached to each side of the trailer. These posts prevent the boat from moving laterally as it slides on the trailer.The bunk guide-on is the second type. These act much like the side rails on a bunk bed. Bunk guide-ons are supported by two small posts on either side and normally have a carpeted board between each post. One bunk guide-on is mounted on each side of the boat.


Guide-ons come in several heights. Post style guide-ons normally range from 36 inches to 60 inches in height. The higher the guide-on, the easier it is to see. Bunk style guide-ons are normally much lower and are usually at a height of 18 inches to 24 inches. Bunk style guide-ons have less visibility but usually supply more lateral stability.


An excellent feature of guide-ons is their ability to act as light mounts. Trailer lighting is notoriously susceptible to malfunction. Trailer lights fail because they are immersed in water everytime a boat is launched or recovered. Mounting trailer lights on guide-ons raises the lights much higher. This reduces the number of times the lights are immersed in water and lengthens their service life.


Metal guide-ons are extremely stable but can cause scratching on the exterior of boats as they are loaded. This scratching can be eliminated by covering the guide-on with PVC or foam.

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