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How to Measure a RIB Boat?

How to Measure a RIB Boat?

If you are considering getting a Rib boat, of course, you want to check out every angle before making your decision.

The boat’s condition, age, and accessories are all important. But when you get ready to measure the Rib boat’s size, it is important to know the best way to measure and to know why it’s so important to measure the Rib boat in that way.

Let’s take a look at the unique way to measure a Rib boat, and see why this is so important to your investment.

How to measure a RIB boat?

There are general rules to measuring any boat. Two terms are typically used. Length overall refers to the maximum length of the hull. This is measured parallel to the waterline. Length at the waterline is usually shorter because it does not account for bow or stern protrusions.

Measure in a Straight Line

measuring RIBs in a straight line

Start by extending a tape measure in a straight line, according to Boat Safe. You should create a firm line through the middle of your boat. Avoid the temptation to measure around the hull. This will yield an inaccurate measurement because Rib boats are naturally rounded.

You may consider using masking tape to keep your tape measure sturdy as you measure. Just secure one end of the tape measure as you extend it forward, and then secure the other end to easily view the length of the boat.

Start at the Bow

start to measure RIBs at the bow

Begin your measurement from the tip of the bow. Extend the tape measure all the way to the back of the Rib boat. Be careful to include any reinforcement your Rib boat may have on the stern.

This is where measuring a Rib boat is different from measuring other boats. When measuring a Rib boat, do not include the outboard motor, motor brackets, the bowsprit, or any handles or attachments.

But you should include in your measurement the anchor in the front, and anything that is hanging over the back of the boat. Include rollers, and complete your measurement at the tube cone. You can include anything that improves the Rib boat’s buoyancy.

Some exceptions

An exception occurs if your brackets extend beyond the end of the tube. In this case, do not include the brackets. If you have a swim platform attached, do not include that either.

Also, exclude the bow planks and the rudder. So, with those exceptions, use your tape measure in a straight line right through the Rib boat’s centerline.

Why Measure a Rib Boat?

The most coveted Rib boats are long and narrow, usually with V-shaped hulls.

When buying or selling a Rib boat, length is a primary factor in determining the Rib boat’s value. So you want to be sure to follow these measuring guidelines in order to get the best Rib boat for your money.

The value of long and narrow Rib boats is recognized by many groups, because of their speed and flexibility. Rib boats are used by the military and by law enforcement to catch lawbreakers. Commercial and recreational users select Rib boats to increase profits and to have more fun.

Why is Boat Size Important?

There are four major reasons why boat size is important.

Choose an appropriate boat cover

Seamax Inflatable Boat Cover

The first is so you can choose an appropriate cover. You will want to cover your boat if you are storing it outside. This is to protect the boat from the sun and weather conditions.

Selecting a cover that is too large can cause the cover to balloon. It can also result in pesky water accumulation.

Selecting a cover that is too small is equally undesirable. Besides being tight, covers that are too small are difficult to keep in place.

Boat Size Affects Insurance Rates and Market Value

Emaxusa Inflatable Boats for Adults Aluminum Transom 4 Person Mini Fishing Boat

Insurance rates are the second reason that size is important. A longer boat may result in a higher insurance price. State laws often base equipment mandates on boat length.

If you are looking to sell a Rib boat, you will want to know its length, width, and height. Buyers will want this information to compare with other Rib boats. You will also want to include these dimensions in your sales advertising.

Boat Size Is Important When Choosing an Anchor

Boat size Is important when choosing an anchor

The third reason that size is important is you need to know it to buy an anchor. Longer boats normally need longer chains, while shorter boats require fewer chains. If you decide to dock your Rib boat, length is the primary factor in space selection and dockage fees. Of course, you will also need to know the boat length to select the right-sized trailer.

Longer Means Faster

the length of a boat has a direct correlation to its speed

The fourth reason size is important is the length of a boat has a direct correlation to its speed. Simply put, if everything else is equal, a longer boat may go faster.

But why is this? According to Sailing Magazine, as a boat moves a wave is produced beneath it.

The speed of this wave determines how fast the boat will go. As the length of the wave increases, the boat’s speed increases. The boat’s hull acts as a piston because it pushes this wave up at the bow. This creates a crest at the front of the boat.

The length of this wave is determined by how fast the boat is going and by how long the boat’s waterline is. A longer waterline makes a longer wave. For example, a boat that has a 20-foot waterline would result in a hull speed of six knots. In comparison, a boat that has a 40-foot waterline would generate a hull speed of 8.5 knots.


When measuring a Rib boat, use a tape measure and measure in a straight line. Measure through the center of the boat from the tip of the bow to the stern. Don’t alter your measurement for curves or bumps.

Knowing the correct measurement of your Rib boat is important when choosing a cover, purchasing insurance, and docking. The length of your Rib boat is a major factor in determining how fast it can go, due to the wave that is created beneath it as it moves forward.

When selling a Rib boat, include its size in your advertisements as this will be important to potential buyers.

So measure your Rib boat accurately and, above all, have fun with it.