What Is the Correct Way To Measure the Overall Length of a Boat?

Measuring the length of your boat is not exactly fun or easy, but it’s something necessary that you need to do when you get a boat. However, if you’ve just bought a boat for the first time, you may have a hard time figuring out where to start and how to proceed. Fortunately, there is one correct way to measure the length of your boat that is easy to understand.

The correct way to measure the overall length of your boat is to determine the distance between the tip of the bow and the stern of your boat. As you measure, you should not follow the curve of the boat and instead stay in a straight line. You should not include outboard motors in the measurement.

In the rest of this article, I will show you the best way to measure your boat and guide you through the whole process, step by step. Moreover, I will answer some additional questions you may have and show you how to measure other parts of your boat.

The Best Way To Measure the Length of a Boat

Measuring the overall length of your boat may seem pretty straightforward, but when you start to consider all the aspects, it may seem quite challenging. Your boat is made of several different parts and you may wonder which should be measured and which should not.

If you’re thinking of just winging it and measuring the boat length according to your own ideas, you will be making a mistake. There is a correct way of measuring the length of your boat, which is determined by authorities and laws. Any other ways will be flawed and will not be able to measure your boat correctly.

The correct way to measure the overall length of your boat is to measure a straight line from the tip or the bow of the boat to the stern. This distance from one end to the other determines the exact length of the boat that you will need to use for different reasons, which I will explain below.

Steps To Measure the Overall Length of Your Boat

Although this way of measuring your boat seems easy, it may be more complicated in practice, because of the shape of your boat. Here are the steps that you should follow to measure the length of your boat:

  1. Find a measuring tape or something else to measure the boat with. If your boat is relatively small, you can easily use a typical measuring tape, but you may need special equipment for a larger boat.
  2. Start measuring from the tip of the bow and go in a straight line until you get to the stern. Make sure the line is completely straight.
  3. You may consider following the curve and measuring around the hull, but that will not result in an accurate measurement. Keep the line straight at all times.
  4. Avoid any obstacles. The boat has plenty of bumps and curves, as well as appendages. Make sure to avoid them and not include them in the measuring process. You only need the length from the tip to the stern.
  5. If your boat has an outboard motor, it should not be included in the measurement. The motor is considered a removable appendage, so it’s not a permanent part of the boat; hence, it’s not to be included in the overall length.
  6. If you have a very large boat, you may need the help of other people to complete the measurement. The special measuring equipment itself may require at least two people to measure the length of your boat.

Should I Measure the Deck Extensions Like the Swim Platforms?

While measuring from tip to stern seems reasonable, sometimes it’s not as simple. Some boats have swim platforms or other deck extensions, which can add to the overall length if they are included in the measurement. Should they be included?

A swimming platform or other similar type of deck extension is typically a permanent part of your boat, so they both should be included in the length measurement. The measurement process does not change, you still need to measure in a straight line, but you should include the platform as well. 

As for motor brackets or outboard motors, they should not be included, as I explained above. Legally, these parts are not required to be measured when sailing. However, you may need to include them in your measurement if you’re going to move your boat using a truck. In this case, you must include every potential part that can add to the length of your boat.

Why You Should Know the Length of Your Boat

There are several reasons why you need to know the length of your boat. The first and most important reason is the fact that the law requires it. When you buy a boat, you are required to register it, to use it without authorities stopping you and seizing it. When you register your boat, you need to include the overall length in the description.

Secondly, you need to know the exact measurements of your boat in case you decide to dock it at a pier while you’re sailing. You should know the space that your boat takes to arrange for a spot at any pier that you find. 

You should also know the length of your vessel to buy the right insurance for it. Your boat must be insured to make sure your investment is protected in any case, but you can’t properly insure your boat until you know exactly how large it is. The larger the boat is, the more expensive the insurance is going to be.

Additionally, you need to know the length and other measurements of your boat to make sure you buy the right equipment. To make sure you always sail safely, you should include several life-saving additions, like lifeboats, life jackets, anchor chains, and more. However, you can’t decide what to get until you know how much space there is inside your boat. You also need to know the exact length to buy a proper boat cover.

Finally, you need to know the length of your boat to be able to list it for sale. If or when you decide to sell your boat, you need to provide all the necessary information so that potential buyers know exactly what they are dealing with. The length is probably the most important measurement you need to include.

Other Important Measurements

Besides length, there are a few other ways in which you need to measure your boat to have more information about the equipment you need to use and to be able to list it for sale. For instance, you also need to know the height and width of your boat, as well as the load waterline. Let me explain what these measurements are and how to do them correctly.

How To Measure Your Boat’s Height

The height of your boat is the distance between the bottom of the keel or backbone and the highest point of the vessel. It’s important to remember that you should only measure up to the highest part that is non-removable; any removable or non-permanent part should not be included in the measurement.

You should know the height of your boat because of the reasons listed above, especially if you’re planning on sailing under bridges. Additionally, it’s very helpful if you’re transporting your boat from one place to another. To measure the height, you may need measuring equipment as well as a ladder.

How To Measure the Beam

The beam or width of your boat is measured by determining the distance between two sides of your boat at the widest part. Typically, this part is near the middle of the boat, but you need to make sure you measure the outer extremities, not the inner ones.

You should know the width of your boat so that you can sail through canals and narrow passages with confidence, knowing that your boat is not likely to be stuck or to just avoid any of these passages if you know that your boat won’t fit. This measurement is also important for transporting the boat and letting potential buyers know exactly how large the boat is.

Take a look at our article: What Is The Beam Of A Boat (Full Breakdown)

How To Measure the Load Waterline

The load waterline is the length of the boat when it’s on the water. To measure the load waterline, you need to measure the maximum length of the part of the boat that stays above the water. When determining the length of this part, you should keep in mind to always measure in a straight line, without following the curve of your boat; otherwise, the measurement will be wrong.

The load waterline is important to know because it can help you determine the amount of water your vessel displaces when it’s on the water. Additionally, it can help you decide how much paint you need to use for the underwater part of your boat.

Beam of a boat


It’s important that you know the basic measurements of your boat because they are essential for the registration of your vessel, but also because they can be a factor that determines the equipment you buy, the insurance, and how you use your boat.

The overall length is one of the most important measurements. The correct way to measure the length of your boat is to measure the straight line between the tip of the bow and the stern of the boat. Keep in mind that you should not follow the hull and just measure a straight line instead.

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Check out our article on: Best Deck Boats On The Market: (Top 6)

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Project Boating Editorial Staff

My name is Brad Visser the chief editor and owner of Projectboaing.com. We have an amazing team of writers that contribute to our website. This team is passionate about boating and have years of experience not only in boats, but in writing helpful, informative articles to answer questions you may have.

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