How Long Can You Leave a Fiberglass Boat in the Water?

Fiberglass is lightweight, durable, and perfect for recreational boats. If you have a fiberglass boat that you use occasionally, you may want to leave it in the water between trips. But how long can you leave a fiberglass boat in the water before damage occurs?

You can leave your fiberglass boat in the water for a month without causing any damage. Fiberglass boats are durable, saltwater resistant, and don’t leak easily. However, leaving it in the water for too long can cause cracks, hull damage, rusting, and water saturation. 

In this article, I will discuss the factors affecting how long you can leave a fiberglass boat in the water. I will also explain what happens if you leave your boat in the water for too long and give you some tips on strengthening your fiberglass boat to make it last longer. 

How Long Can a Fiberglass Boat Be Left in Water?

You can safely leave your fiberglass boat in freshwater for more than a month and in saltwater for a couple of weeks. Fiberglass is water repellant and won’t get damaged easily even if left in the water for several weeks. 

Some boats can be left in the water for several months and will still be seaworthy. However, constant exposure to the sun’s UV rays may damage the paint, cause minor cracks and give your boat a faded look. 

If you use the boat regularly, you can leave it in the water for longer. However, algae and barnacles may grow on the hull if it’s docked for long periods of time. 

Also, avoid leaving your fiberglass boat for too long in areas where waves or tidal changes can damage the hull over time. In general, you can leave your boat docked for longer in calm freshwater than in rough seawater. 

What Happens if You Leave a Fiberglass Boat in Water for Too Long? 

If you leave a fiberglass boat in the water for too long, it can result in hull damage, water saturation, or cracks forming on the hull. Leaving it in saltwater for too long may corrode the metal parts, even if they’re galvanized. 

Let’s go into detail about some common problems you’ll face from leaving a fiberglass boat in the water for too long: 

Hull Damage

Algae, barnacles, and other organisms can cause hull damage over time. They can widen microscopic cracks, causing the inner fiberglass layers to get damaged. These organisms take time to grow on the boat’s hull, so avoid leaving your boat in the water for too long. 

Water Saturation

Fiberglass can absorb water, so the resin coating is applied to protect it. Leaving your boat in the water for too long can cause cracks in the resin, resulting in water saturation. If the cracks are minor, they may only cause boat blisters. However, in extreme cases, it may result in structural damage. 

Cracks 

Cracks can form when you leave your boat for too long in rough water. These cracks are microscopic at first and slowly widen until they become a major problem. Always repair cracks as you notice them to prevent long-term damage. 

Rust 

While fiberglass won’t rust, the railings, engine parts, and other metal areas may. Leaving your boat in the water (particularly saltwater) for too long may cause these parts to rust, even if they’re covered with a protective zinc coating. 

How To Preserve Your Fiberglass Boat for Longer?

Fiberglass boats are built to last more than 50 years. However, there are ways to prolong your boat’s life, especially if you leave it in the water for extended periods. 

You can preserve your fiberglass boat by washing it regularly, applying gelcoat to protect the bottom, using a growth repellant, and waxing the boat regularly. Regular maintenance checks and fixing minor cracks will also prolong the boat’s life. 

Here are some tips to help you maintain your fiberglass boat for longer: 

Wash the Boat

Washing fiberglass is easy and helps expose any cracks or damaged areas. You can use a normal brush to scrub the algae off the hull. Remove any barnacles to prevent them from damaging the boat. 

Apply Gelcoat to the Boat 

Gelcoat is the perfect paint to protect fiberglass boats. It’s a shiny liquid that hardens and can leave your boat looking brand new. Apply gelcoat to form a protective coating on the underside of the boat. It can help to reinforce and strengthen the hull.

Prevent Algae and Barnacle Growth With a Growth Repellant

Growth repellent (aka anti-fouling paint) will reduce the growth of algae, barnacles, and other organisms on the boat’s hull. Apply it thoroughly on the underside of the boat when you know that you have to leave it in the water for a long time, and it will help prevent these organisms from damaging your boat. 

Wax the Boat 

Waxing your boat’s deck can prevent paint damage and will combat fading caused by sun exposure. Wax your boat every few months to prevent discoloration and rust. If you don’t have time to wax the boat, use a buffer and boat polish instead. 

Fix Minor Cracks 

Minor cracks may look harmless, but they can widen over time and cause saturation. Inspect your boat regularly for minor cracks, and you’ll prevent boat blisters and other water saturation problems. 

Do Fiberglass Boats Absorb Water? 

Fiberglass boat hulls do absorb water over time, even if they’re painted thoroughly, or epoxy coated. However, this won’t damage the boat since most fiberglass boats will only absorb 10 – 15% of their weight in water. 

This may cause boat blisters which may affect the aesthetics of your boat. However, boat blisters aren’t a major problem in most cases and won’t affect the boat’s performance. They may cause structural damage in severe cases, but this is rare. 

Conclusion

Fiberglass boats are designed to last for several decades. However, leaving your boat in the water for longer than a month can cause hull damage, faded paint, and water saturation. It may also cause structural damage in rare cases. 

To prevent damaging your fiberglass boat, avoid leaving it in the water for more than a month and clean it regularly.

Painting it with gelcoat, waxing the deck, and applying growth repellant to the hull bottom can preserve your fiberglass boat for longer.