×

How to Adjust a Jet Ski Trailer

by Will Charpentier
The fun really begins when you load your jet ski onto its trailer.

The fun really begins when you load your jet ski onto its trailer.

Your jet ski may be a blast on the water, but getting it to the water safely means adjusting the trailer to meet the towing needs of a jet ski. When you tow a jet ski, its hull must be supported from side to side. Its fore and aft position on the trailer influences the trailer's tongue weight and, consequently, the safe handling of the trailer and vehicle combination. Proper adjustment requires only an adjustable wrench and a bit of brawn. Without proper adjustment, you risk wrecking the trailer, damaging your jet ski and vehicle, and suffering personal injuries.

Trailer Architecture

The trailer for your jet ski provides longitudinal and lateral support to the jet ski's hull while supporting its weight. The support comes from three or more padded skids, called bunks, that lie parallel to the trailer's center line. The bunk on the center line is called the keel bunk and is not adjustable. It bears most of the jet ski's weight that's transferred to the bunk and the trailer through the jet ski's keel. You can adjust the other bunks on the trailer to fully support the sides of the jets ski's hull. These adjustable bunks provide side-to-side support for the loads on the jet ski.

Bunk Adjustment

To determine the proper position of the two adjustable bunks, locate the two V-shaped creases -- the chines -- running the length of the jet ski's bottom and measure the distance between the first and second "V." Divide by two. The result is the number of inches you must move the two adjustable bunks from the center of the keel bunk to support the sideways loads on the hull as you tow the jet ski. For example, if the distance from the higher chine to the lower chine is 18 inches, you should loosen the nuts that hold the adjustable bunks in place on each side of the keel bunk, using an adjustable wrench. Move each of the bunks so they are 9 inches from the center of the keel bunk and re-tighten the nuts.

Tongue Scale

Stand a concrete block on end and set a bathroom scale on top of it. Set the trailer tongue on the scale so that you can adjust the tongue weight as you position the jet ski on the trailer. Look in your owner's manual and locate your jet ski's weight. Multiply your jet ski's weight by 0.10. This is 10 percent of the jet ski's weight and the maximum weight you should show on the scale when the jet ski is loaded onto the trailer. Multiply the jet ski's weight by 0.007. The result is 7 percent of the jet ski's weight, which is the minimum tongue weight for the trailer. To adjust the tongue weight, move the jet ski forward or backward on the trailer, checking the scale with each move until it shows that you have between 7 and 10 percent of the jet ski's weight on the tongue.

Adjust the Winch Bed

Remove the adjustment bolt from the trailer's winch bracket adjustment bracket using an adjustable wrench. When you do so, slide the winch drum toward your jet ski; it should touch the jet ski's bow. Slip the adjustment bolt back into the winch bracket's lowest adjustment hole. Tighten the bolt and clip the winch wire to the jet ski. Strap the jet ski into place, tighten the straps and tie the loose ends of the straps over the cam-lock buckles used to tighten the straps.

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

Photo Credits

  • Stockbyte/Stockbyte/Getty Images