How to Adjust Boat Trailer Bunks

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Like your boat, your boat trailer's bunks--the padded, adjustable skids the boat sits on while on the trailer--will require occasional adjustment to carry your boat properly. If the bunks are adjusted correctly, your boat will ride on the trailer roller beneath the keel, where the majority of your boat's weight is concentrated, and the boat will be cradled in a steadily on the trailer. Because the keel roller bears the weight, the bunks can be moved without moving the boat from the trailer.

Items you will need

  • Adjustable wrench

  • Torque wrench

Inspect the boat's keel--the lowest part of the bottom--to verify that the keel is resting on the line of rollers in the center of the trailer. If it is not, use your adjustable wrench to loosen the bolts that hold the keel roller in place. Starting at the front of the boat, raise the keel roller until it touches the bottom of the keel. Tighten the first bolt, move to the next bolt and repeat the process. After the initial tightening with the adjustable wrench, use a torque wrench to torque the bolts to the extent specified in your trailer's owners manual. Your boat will rest on the bunks while you adjust the keel roller, so no further adjustment of the bunks is necessary.

Adjust the bunks if your boat is setting on the keel, but is "tipsy" on the trailer. Use your adjustable wrench to loosen the bolts that hold the bunk supports in place on the trailer.

Raise the forward end of the bunk until it touches the bottom of the boat and tighten the forward-most bolt. Repeat until the whole bunk touches the bottom of the boat and all the bolts on the bunk have been tightened.


  • Though the weight of the boat is supported by the keel roller, don't put your fingers between the bunk and the boat.
  • Bumps in the road will eventually jar all the bolts on the bunks and keel roller loose.


  • Check the stability of the bunks each time you take the trailer out and adjust them if necessary.