Your Ultimate Guide to Boat Transoms

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Learn what a transom looks like, what it does, and how to repair it if it gets damaged

Co-authored by Devin McSween

Last Updated: March 31, 2023

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Transom Definition

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Transom Uses

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Can a transom get damaged?

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Can you repair a transom?

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Caring for a Transom

You might be familiar with the hull and stern on a boat, but what is a transom? And is it important? On most boats, the transom is the vertical reinforcement at the stern of the boat. There’s definitely a lot of terminology to learn and remember when boating, so we’re here to tell you more about what the transom is and what it does. Then, to help you boat safely, we’ll tell you what to look out for and do if your transom gets damaged.

Things You Should Know

A transom is a flat structure at the back of a boat that motors are usually attached to. It reinforces and supports the back of the boat.
Over time, stress from the motors can cause cracks to form on your transom that water leaks into. As more water enters, the transom can rot.
The best way to repair a damaged transom is to replace it. Once water enters and rots the transom, its structure is difficult to fix.
To care for your transom, check it regularly for cracks and peeling seals. If you suspect it's wet, get a professional to take a sample.

Section 1 of 5:

Transom Definition

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The transom is the flat, vertical structure at the stern, or back of the boat. A transom is typically rectangular and sits at the very end of the boat. While its height can vary, it usually acts as a sort of wall to the back of the boat. Most motors are attached to the transom, which can make it easy to identify.^{[1]
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- Lots of boaters put the name of their boat on the transom, which is another great way to tell where it is.
- Transom and stern are separate things, though they’re often used interchangeably. The stern is a direction, while the transom is a structure on the boat.
- Transoms can come in many different shapes and sizes. Depending on the type of boat and its size, they might be rounded or square. They also aren’t all flat, as some are angled upwards or downwards.

Section 2 of 5:

Transom Uses

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Reinforces the back of the boat Because the transom is a structural piece, one of its main purposes is to protect and support the back of the boat. Mainly, it acts as a barrier that helps prevent water from entering the boat.^{[2]
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- If the boat has a motor, the sturdiness of the transom also helps to absorb the motor’s energy.
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Holds the outboard motor Most recreational boats like fishing boats, bowriders, and consoles have motors that propel the boat. Motors need a sturdy place to hold onto that can withstand their power, which the transom provides.^{[3]
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- The size of the transom often depends on how many motors are on the boat. A boat with 2 or more motors puts a lot of stress on the transom, so it needs to be thicker.
The support of the transom also makes it a great place to install ladders, rear doors, and swim platforms on recreational boats. This gives passengers an easy way to enter and exit the boat from the back.^{[4]
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Section 3 of 5:

Can a transom get damaged?

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Cracks and loose sealing allow water to leak in your transom, damaging it. Constant stress from the motor and supporting the back of the boat can cause cracks to form. Along with natural wear to the sealants and bolts, this allows water to enter the transom. With time, that water can cause your transom to rot. Your transom is a main support for your boat, so it can be dangerous for water to leak into it.^{[5]
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- Any damage to your hull can damage your transom, too. Scratching the bottom of your boat when you’re in too shallow water or hitting debris at high speeds can crack your transom.

Section 4 of 5:

Can you repair a transom?

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The best way to repair a damaged transom is to replace it altogether. Unfortunately, once water rots the transom, its structure is compromised. Even if you are able to dry it out, the transom no longer functions like it’s supposed to.^{[6]
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- Replacing your transom with a professional can cost around $1,500 to $5,000, depending on the size of your boat. While that’s certainly not cheap, it’s super important that you have an undamaged transom to boat safely!
This typically involves removing the rotting wood and fiberglass exterior, outlining the shape of the transom on 1.5-inch (3 cm) thick marine plywood, and cutting it. You then apply resin to the back of the transom to adhere the plywood to the boat. Then, apply fiberglass over the plywood to finish the repair.^{[7]
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Section 5 of 5:

Caring for a Transom

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It’s always best to catch any problems with your transom before they develop. Every time you take your boat out and bring it back in, inspect your transom. Look for any cracks, leaking, or peeling seals around bolts and screws, and any loose fittings, bolts, or screws.^{[8]
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Look for signs that your transom is wet. If you think your transom might have a leak, the best way to make sure is to get a professional to take a sample and see if it's wet. However, you can check yourself by knocking on the transom. If it sounds hollow, you might be dealing with rot. ^{[9]
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- Rust stains below screws and bolts, warping, and cracks are also common signs your transom is rotting.
If you keep your boat at home and transport it to a marina, your transom can also get damaged from road bumps and potholes. A transom saver is a small bar that you attach to your trailer, lifting the bottom of your boat further from the road. This relieves the pressure on your transom and protects it from any potential damage.^{[10]
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