Ridetheducksofseattle is reader-supported. When you buy through our links, we may earn an affiliate commission. Learn more

How Wide Is a Boat Trailer? Important Things to Know!

Written by Anthony Roberts / Fact checked by Jonathan Larson

how wide is a boat trailer

A boat trailer is needed by every boater to transport a boat. It also helps with storage and cleaning and maintenance. When you get one, you have to think about ‘how wide is a boat trailer?’

Most states set the standard boat trailer width at 8.5 feet. But Hawaii, New Jersey, and New York set the width of a boat trailer at 10 feet.

When you move or visit another state, you have to confirm their requirements. Some boat owners have a trailer with a wider beam. They will be allowed by the local authority after they secure a wide-load permit. To know more about this matter, read on.

How to Measure a Boat Trailer

Besides the requirement of your local authority, you have to know the boat trailer dimensions to ensure that it does a good job in carrying your boat. In this process, you have to measure the length and width of your boat to know if it matches the trailer.

  • Use a measuring tape to get the exact measurements. Put the tape along the trailer’s centerline and the front side up to the center of the back rail to determine the boat trailer length. The length should be enough for your boat. If it’s insufficient, the trailer will hit the back of your car or other vehicles.
  • Next, you have to check the trailer’s outside width. You can do it from fender to fender or side rail to side rail.
  • You’ll also need to measure from the upper part of the trailer to the ground. In a launching ramp before submerging into the water, a trailer that is 3.5 feet above the ground goes farther down compared to thr one that is only 2 feet away from the ground.
  • When it comes to the weight that a trailer can carry, refer to the placard that shows its GVWR or Gross Vehicle Weight Rating. When getting the boat’s weight, make sure it’s the wet version, which includes the engine, equipment, and fuel.

Important Things About Boat Trailers


1. Types of boat trailers

  • Bunk trailers

Due to the simple design and lower number of parts, this is an affordable type of boat trailer. Because it has a less complicated structure, it means minimal repair and maintenance are needed. Your boat can go deep into the waters whenever you launch and retrieve it. The credit goes to the drive-on capability of this trailer.

You may be impressed by a bunk trailer but its strength has a downside. Submerging it deep into the water makes running gear susceptible to damage. especially if it happens in saltwater.

  • Roller trailers

When you usually launch and load your boat on low tides or at shallow ramps, this is the type of trailer you have to get. It doesn’t need to be submerged in the water, and so, there’s a low chance of its running gear being exposed to saltwater and harmful elements that cause premature damage.

2. Axles and spring

  • Torsion

The torsion axle has rubber cords inside the tubing. A smooth ride is guaranteed as the wheels move up and down while the cords are compressed. Even though every wheel moves independently, shock can be absorbed. The axles are directly mounted on the frame so only a few parts are moved.

Torsion axles are entirely made of galvanized steel so no corrosion will bother you. You’ll notice that hitting the curb won’t cause impact distribution because the impact is on one wheel or more. But with all these advantages, you have to pay more.

  • Spring

The solid performance of spring has been proven by continuous usage for centuries. You can depend on it for steady rides, especially if there are multi-axles on your trailer.

Springs are great at taking shock and load from a pothole or uneven ground. But when the trailer is empty, there will be a bouncy ride.

Repairs on leaf springs are easy but they may be frequently needed due to the all-metal design.

3. Material

  • Galvanized steel

This material can protect the brake lines and light wiring placed inside the tubing. Sadly, it resists corrosion but not rust. Note that galvanized steel is heavier than aluminum, so it has the towing ability to bear a certain weight.

  • Aluminum

Aluminum is lightweight so many find it easy to maneuver in various geographical areas. It can’t give you problems with rusting but it’s prone to corrosion. Due to its weight, it improves fuel economy. Compared to galvanized steel, this is more aesthetically appealing.

For more weight of a boat trailer, check out this article!

What Is the Standard Width of a Boat Trailer?


To get the right thing, you may have been looking for boat trailer width standards. You would likely find the 18 ft boat trailer, which means that it suits vessels up to 18 feet long. This kind of trailer usually has a width of 6 to 8 feet. These numbers represent the average width.

Here’s the size chart for you to know the maximum boat trailer width.

Single Axle Bunk

Boat Length Width Between Fenders Overall Width Weight Capacity
14 – 16 ft 4 ft 5.17 ft 1,000 kg
14 – 15 ft 4 ft 5.17 ft 1,300 kg
15 – 16 ft 5 ft 6.5 ft 1,500 kg
16 – 17 ft 5.59 ft 7 ft 1,800 kg
16 – 17 ft 5.59 ft 7 ft 2,000 kg
17 – 18 ft 5.59 ft 7 ft 2,200 kg
17 – 18.5 ft 5.59 ft 7 ft 2,400 kg
18 – 19 ft 7 ft 8.5 ft 2,600 kg
19 – 20 ft 7 ft 8.5 ft 2,800 kg
20 – 21 ft 7 ft 8.5 ft 2,800 kg
18 – 20 ft 7 ft 8.5 ft 3,000 kg
20 – 21 ft 7 ft 8.5 ft 3,100 kg
20 – 21 ft 7 ft 8.5 ft 3,300 kg

Tandem Axle Bank

Boat Length Width Between Fenders Overall Width Weight Capacity
18 – 20 ft 7 ft 8.5 ft 3,600 lb
21 – 23 ft 7 ft 8.5 ft 3,700 lb
21 – 23 ft 7 ft 8.5 ft 4,200 lb
21 – 23 ft 7 ft 8.5 ft 4,700 lb
21 – 23 ft 7 ft 8.5 ft 5,200 lb
21 – 23 ft 7 ft 8.5 ft 5,600 lb
24 – 25 ft 7 ft 8.5 ft 5,900 lb
25 – 26 ft 7 ft 8.5 ft 6,400 lb
25 – 27 ft 7 ft 8.5 ft 7,400 lb
25 – 27 ft 7 ft 8.5 ft 7,900 lb

Use this chart as a size calculator and determine if you have the right trailer size. A 16-foot boat is the smallest on the chart and it needs the lowest width of 48 inches or 4 feet from fender to fender.

If you have 18-foot, 19-foot, and 21-foot boats, the width is 84 inches or 7 feet, regardless of the type of axle.

But the difference is in the load capacity. If it’s with a single axle, the capacity is 2,600 to 3,300 lb. With tandem axles, it starts at 3,600 and can range to 5,600 lb.

The Takeaway for the Right Boat Trailer!

How wide is a boat trailer? It’s crucial to know the answer to this question so you can transport your boat safely. Moreover, it’s to prevent damage to your boat or vehicle and others that you meet along the way. Trailers usually have a width of 6 to 8 feet. Hence, it’s not complicated to choose one that is perfect for your boat size.

Furthermore, if you want to know the wide of pontoon trailers, don’t forget this article to learn more.

5/5 - (1 vote)