Boat Trailering: Tongue Weight

weight distribution

Too much tongue weight (top) will cause dive, and to little will cause sway, both dangerous.

In my continuing search for the perfect tow vehicle for my 5,000-pound boat and trailer combo I’ve been concentrating on tow vehicle suspension systems. One of the nicest rides I’ve found is an adjustable self-leveling air system on Toyota’s big SUV, the Sequoia. Why is this important? One of the keys to handling is a nice level ride with weight evenly distributed between the tow vehicle’s front and rear wheels and the trailer’s wheels.

To get a level ride, you don’t necessarily need a fancy air suspension system. The position of the boat on the trailer affects tongue weight (TW). Tongue weight is defined as the weight of the trailer on the hitchball. So, even a slight change in the position of the boat on the trailer can affect the balance and tongue weight. In most trailering scenarios a tongue weight of 10 to 15 percent of the total load is ideal. So for my 5,000 pound boat, a tongue weight of 500 pounds or so is acceptable.

weight-distribution-hitch

A load-leveling hitch is designed to spread the load between the trailer and tow vehicle.

With motor boats, where the weight of the motor is farther aft on the trailer, tongue weights of only 6 to 10 percent of the load are more typical. Too little tongue weight can also be a problem, causing “sway.”  When using a deadweight hitch, too much tongue weight can cause “dive” and negatively affect steering, handling, and braking.  Most vehicle manufacturers provide a recommended maximum deadweight tongue rating (stated in pounds). Make sure your tow vehicle and hitch are rated for the tongue weight you will be pulling, and don’t just look at gross vehicle weight rating (GVRW)  on your tow vehicle.

Adjusting the boat on the trailer to balance tongue weight is the first option.  Positioning onboard equipment and even draining bilge water can help. If you are still not getting a level ride, and you don’t have a fancy air-spring system, you might consider a weight-distributing hitch with a spring bar assembly. Spring bars (also known as equalizing bars) are available in different tension ratings. Choose bars that are rated equal to or more than the tongue weight of the trailer. Too stiff or set with too much tension, spring bars can cause loss of rear wheel traction. If your trailer has a surge brake system, beware of using a weight distribution system that is not properly adjusted—it can cause brake failure on the trailer.  Make sure the bars are set perfectly parallel to the trailer’s surge coupler, or the trailer brakes may not work properly. Check with the manufacturer of your surge brake coupler for information on how to set the spring bar chains for your particular equipment.

If the size of your boat makes you a little nervous in using an ordinary bathroom scale to measure tongue weight, click here for a few tips on measuring tongue weight. And here are some more tips on loading a boat trailer. Paying attention to tongue weight and getting a nice level ride will make all the difference in how your tow package performs.

Comments

  1. Richard says:

    I’ve always enjoyed towing with a Land Rover Discovery (3.0 V6 TDi). We don’t often tow a boat but when towing a race car on a trailer it’s easy to forget that you’re towing anything at all! So much power and stability for such a big vehicle. Before the Discovery was a Range Rover Vogue which was equally as good.

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