What are effective methods for storing a boat with a fiberglass hull to avoid cracks?

Fiberglass hulls are durable, but improper storage can lead to stress cracks, spider webbing, or structural damage. To avoid cracks, focus on three main principles: supporting the hull correctly, controlling the environment, and managing temperature and moisture shifts.

1. Use Proper Support Systems

The single most common cause of fiberglass cracks during storage is uneven support. A fiberglass hull is designed to flex slightly under water, but on land it requires consistent, full contact support.

• Trailer storage: Ensure your trailer bunks or rollers are adjusted to match the hull’s contours exactly. The hull’s weight must be spread evenly across all bunks. Check that the keel sits centered on the trailer’s rollers. If bunks are too short or misaligned, concentrated pressure points can cause cracking.
• Indoor or outdoor rack storage: Use a purpose-built cradle or padded stands that conform to the hull shape. Avoid using concrete blocks, narrow jack stands, or any hard, small contact points. The goal is a large surface area for support.
• Dry stack storage: Reputable dry stack facilities use specialized cradles and forklifts designed for each boat model. Verify the facility inspects and adjusts cradles regularly. Many owners report crack damage from facilities with outdated or poorly maintained equipment.
• Marina slips: For wet storage, ensure your boat is properly moored to prevent constant rubbing against docks or adjacent boats. Use fenders appropriate for your hull size and hull shape, and double-check slip width.

2. Control Temperature and Moisture

Fiberglass expands and contracts with temperature changes. Repeated cycles can create microcracks that widen over time.

• Indoor storage is the most effective way to avoid temperature swings. Climate controlled indoor facilities keep both temperature and humidity stable, drastically reducing risk.
• Outdoor storage requires a snug, breathable cover. A cover that flops in the wind can abrade the gelcoat, leading to stress cracks. Use a cover that is specifically sized for your boat model, and tie it down with straps that do not chafe. Allow air circulation underneath to avoid moisture buildup, which can cause gelcoat blistering.
• Dry stack storage offers moderate temperature control because boats are stored indoors but not climate conditioned. Still, it is far better than full outdoor exposure.

3. Avoid Direct Sun and Chemical Exposure

Prolonged UV exposure degrades gelcoat, making it more brittle and prone to cracking. Outdoor storage in direct sun accelerates this process. If you must store outdoors, use a high quality, UV resistant boat cover and consider a storage facility that offers shade or partial covers. Also keep the hull away from fertilizers, deicing salts, or other chemicals that can attack the gelcoat.

4. Perform Pre-Storage Winterization and Checkups

Before storing, thoroughly inspect the hull for any existing chips, scratches, or cracks. Small damage can worsen under the weight of the boat during storage. Winterization is also critical if you store in freezing climates. Water trapped inside the hull (in blisters or voids) can freeze and expand, causing internal cracks. Ensure all plumbing, through hulls, and bilges are drained and dry.

5. Choose the Right Facility

Not all storage provides the same level of hull protection. When evaluating a facility, ask specific questions:

• What type of cradles or racking do you use? Are they padded or form fitted?
• How often are cradles inspected and adjusted?
• Is the storage area climate controlled? If not, what are the typical temperature swings?
• Are there any known issues with rodents or pests that could damage gelcoat?

Facility practices vary widely, so always visit in person and review the storage contract carefully.

6. Insurance Considerations

Most boat insurance policies cover storage related damage, but exclusions are common. For example, gradual cracking from improper support or neglect may not be covered. Confirm that your policy includes coverage for physical damage while the boat is in storage, and ask specifically about crack coverage. Some policies offer “mysterious disappearance” or “full coverage” provisions, but do not assume.

As a general rule, the best way to avoid cracks is to invest in a storage method that supports the hull evenly, controls the environment, and includes routine inspections. Reputable facilities with modern equipment and a focus on boat care are worth the extra cost.