How To Measure A Boat

Ian Fortey by Ian Fortey Updated on December 13, 2022. In Boats

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At first glance you might think that measuring boat length is a simple process. Like everything else, you just measure from the tip to the other end, right? But there is more to it than all of that. In fact, there are different ways to measure a boat that will give you different measurements. These measurements are important depending on the information you need to know.

When you’re looking to measure your boat, you can measure the overall length. You can also measure the load water line. The overall length of your boat is measured from the tip of the bow to the stern of the boat down the center. The load water line measures the length of the boat as it rests on the water. Everything below the load water line will be underwater.

How to Measure the Length of a Boat

You need to remember when you measure your boat to keep your tape measure in a straight line down the center. There is a temptation to measure around the hull of a boat. You can’t do that. Your tape measure will curve around the bow of the boat. You’re not going to get an accurate length. You need to measure from the tip of the bow all the way to the transom in one straight line. No curves and no bumps. No need to include the motor if you have an outboard. Avoid anything in the way, like equipment or other parts. Anything that will skew a straight measurement.

What About Swim Platforms?

If you have an integrated swim platform, that will affect the measurements of your boat. You should include this when measuring the length of your boat. To be thorough, you can measure the boat from tip to stern, and then add the length of a swim platform as well. Swim platforms typically add a couple of feet.

What About Other Deck Extensions?

Your boat may feature an outboard motor and motor brackets. It may also have a bowsprit, or handles and attachments. Those are not to be included in the overall length when you measure your boat. However, there may be an exception. When it comes to a situation like transporting a boat, these attachments may be relevant.

For pontoon boats, a sailboat or a boat with outboard motors, dimensions are important. Moving a boat with a mast, pontoons, outboard motors is a different situation. It does not affect the laws and regulations around your boat, but it will affect transportation.

Measuring the beam. The beam refers to the width of your vessel. This should be measured at the widest point of the boat. The widest point is generally somewhere in the middle. If you can’t eyeball the boat measurements, try a couple of places. Eventually you will find the beam.

Measuring the height. The height of your boat is taken from the keel all the way to the boat’s highest point. This is important to know for transportation requirements. Boat height is especially relevant when dealing with sail boats. Boaters need to know if the height of their sailboat prevents travel in certain marinas. Or under bridges.

Why is Knowing the Measurements of a Boat Important?

Different types of vessels are grouped by their length. There are four basic category groupings based on this.

  • Pleasure craft that measures 6 meters or less in length.
  • Non pleasure craft that measure 6 meters or less in length
  • Pleasure craft that measure more than 6 meters in length
  • Non pleasure craft that measure more than 6 meters in length

Knowing the length of your boat is essential for several aspects of boating.

  • You need to know the overall length of your boat to properly fit a boat cover. If you do not have an accurate measurement of your boat, it could cause issues. Boat covers that are too large can balloon or collect water. Boat covers that are too small can be a struggle to get on and may pop off.
  • Knowing the correct length of your boat is also important for insurance purposes. A large vessel may have more costs than a smaller vessel. Also, there are state laws that apply to a larger vessel in terms of safety equipment. This means things like a fire extinguisher or an air horn.
  • If you ever want to list it for sale, having an accurate length, width and height is important. Buyers want accurate dimensions, and it will help you secure a sale if you have accurate details.
  • The length of the boat is an important factor in determining how much chain you need to buy for your anchor. The height of a sailboat is important for knowing things like how much sail you need.
  • Docking fees are based on the length of your boat. Larger boats take up more space and will cost more money. Storage costs for larger boats needs to be properly calculated.
  • The size of the trailer that you use for boat transportation is going to depend on the length of the boat. The beam is also a factor here. A vessel with a large keel cannot go on the same trailer for transportation purposes that a small boat can.
  • Along with the size of the trailer, you need to consider transportation costs for your boat. If you are paying to have your vessel moved, it will cost you more to move a larger boat. Smaller boats can often be moved more easily. Large vessels may require something like a flat rack.
  • There are also regulations regarding transportation when it comes to boats. Certain size boats are not allowed on certain roads. This may depend on the time of day. Transportation logistics need to be researched in advance. That’s why knowing accurate measurements is important.

About Ian

My grandfather first took me fishing when I was too young to actually hold up a rod on my own. As an avid camper, hiker, and nature enthusiast I'm always looking for a new adventure.

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1 Comment

  • Jay Vander Plaat on September 28, 2021

    I had a Triton 2286. It measured 22′ long. My wife retired and we looked for something more comfortable and bigger. We bought a 23′ Bryant. Loved it till the first choppy day. Ha it rode terrible. What I bought was a 21′ boat with a 2′ swim platform. Thought I was buying bigger better riding boat, in reality it was smaller. Needless to say, 4 boats latter I know have a Boston Whaler 280 Vantage. Still not sure if it rides better than the 22′ Triton? Ha. Difference between standing against a leaning post in the back of a center console vs sitting behind a windshield toward the front of the boat. Lessons learned. Money wasted. Becareful at Boat shows, even test rides can be misleading when the shiny new boat bug bites.


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