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Know Your Tow Vehicle

Got enough power to pull the boat? A little bit of math will show if you can do this safely.

Truck and trailer with boat illustration

Everyone looks at the boat. Some look at the tow vehicle. As for the trailer? But the three of these have to operate as one unit. So let's start where everything starts: with the vehicle that gets you, your passengers, the boat, and, yes, the trailer to the water

Gross Vehicle Weight

The truck's Gross Vehicle Weight Rating (GVWR) is equal to the curb weight of the truck, plus the payload capacity. The payload capacity tells you how much the people, gear, pets, and everything else in or on the truck can weigh before the truck is overloaded.

Gross Combined Weight Rating

The truck's Gross Combined Weight Rating (GCWR) is the maximum amount of weight at which the truck can safely get moving (and stop!) The tow vehicle plus the boat/trailer combo must be added together to arrive at this weight. This number is frequently, but not always, equal to the vehicle's curb weight, plus the towing capacity, plus the weight of the driver (180 lbs.) You'll notice that this leaves no room for any gear or passengers. Therefore, don't try to exactly match the truck's tow capacity with the weight of your boat and trailer. Experts suggest that the fully loaded boat/trailer be no more than 85 percent of the tow capacity (GTWR).

Gross Trailer Weight Rating

This is the truck's tow capacity: This is the maximum weight that can be towed by the tow vehicle, also called Gross Trailer Weight Rating (GTWR). The truck's tow capacity has to be greater than the total weight of the boat, trailer, engine(s), fuel, and equipment on its trailer.

Do the Math

1. Gross Vehicle Weight

(Curb weight + payload + tongue weight)

2. Towing Weight

(Weight of fully loaded boat, motor, and trailer)

3. Gross Combined Weight

(Answer from Line 1 plus Line 2, minus tongue weight)

Your answer from Line 1 must be LESS than the vehicle's Gross Vehicle Weight Rating. Your answer from Line 2 must be LESS than its Towing Capacity, and your answer for Line 3 must be LESS than its Gross Combined Weight Rating (and ideally no more than 85% of that number).

How Do I Find All Of This?

Every new tow vehicle's tow capacity can be found on the manufacturer's website but it can be confusing. Usually, it's located under "specifications" or "capacities"; but a few manufacturers list it under "dimensions" as a subcategory or "exterior measurements."

Tongue weight ...

Is defined as the weight of the trailer tongue on the hitch of the tow vehicle. You want a tongue weight equal to 7-12% (for single-axle trailers) of the total weight of the fully loaded boat/motor/trailer combo.

Be sure to include:

Your water tank on the boat: 1 gallon of water weighs about 8 pounds. Your fuel tank on the boat: 1 gallon of fuel weighs about 6 pounds.

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John Tiger

Contributor, BoatUS Magazine

John Tiger is a freelance boating writer and frequent contributor to many magazines.