Do Fiberglass Boats Rot?

Fiberglass is a popular choice for hull construction on a boat. Its durability and light weight make it a great choice for maximizing a boat’s power-to-weight ratio on the water. But how long does it last?

Rotting fiberglass boat

A well cared-for fiberglass boat can last more than 50 years, but there are some vulnerabilities that can shorten its lifespan.

What Damages Fiberglass Boats?

UV rays will damage a boat, and that’s tricky because most people do their recreational boating on sunny days. Another thing to think about is water saturation. 

Fiberglass boat damage

When water gets into the hull and the boat’s surface isn’t cared for, water can react with materials in the fiberglass and cause it to break down. If your boat is in saltwater, the salt can get into the pores of the fiberglass and cause damage.

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How to Inspect a Fiberglass Boat

There are three telltale signs of damage to a fiberglass boat:

Cracks — The first signs of cracking in fiberglass will be small, almost invisible hairline cracks. But once they form, they grow and flex, creating more and more stress on the surrounding fiberglass.

Fatigue — Over time, vibration from engines and rough water can stress and fatigue fiberglass, causing it to become weak and brittle.

Water damage — Water can get behind the resin that protects the fiberglass and infiltrate it, which eventually leads to blistering and cracking.

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You want to look everywhere for warping that may be a sign of heat damage from long-term exposure to the sun. Gelcoat repair products and fiberglass repair kits are available to help you deal with damage to the hull.

Will the Fiberglass Itself Rot?

Fiberglass is vulnerable to damage, but because it’s made of plastic, glass fiber and resin, it’s probably not going to rot. On the other hand, the wood behind the fiberglass that’s often used to give a boat its shape can rot. So it’s important to inspect for water damage to make sure your boat’s integrity isn’t compromised.

Fiberglass boat water damage

How to Protect a Fiberglass Boat

Cleaning a fiberglass boat is a great way to keep it in good shape. Doing so keeps contaminants that get picked up in the water off of the hull when you pull it from the water. Pay special attention to the area between the railing and the waterline. The combination of spray from running your boat and exposure to sun make this area and the decks especially vulnerable to oxidation and fading. 

Fiberglass boat in water




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