How do I prepare a fiberglass boat for storage compared to an aluminum boat?

While the core principles of boat storage-cleanliness, winterization, and damage prevention-apply to both fiberglass and aluminum boats, the specific threats each material faces require distinct preparation steps. Understanding these differences is key to preserving your vessel’s value and integrity during any storage period, whether it is a few months or an entire season.

General Preparation Steps for All Boats

Before addressing material-specific concerns, complete these universal tasks for any stored boat. Consult your owner’s manual for exact procedures, but these steps form a solid foundation:

• Thoroughly clean and dry the entire hull, deck, and interior. Remove all dirt, salt, algae, and organic matter. Dirt holds moisture and can cause corrosion or mildew.
• Flush the engine’s cooling system with fresh water. For outboards and sterndrives, run the engine on a hose or in a tank to clear salt and debris.
• Stabilize the fuel system. Fill the tank to 90% capacity and add a marine-grade fuel stabilizer. Run the engine to circulate the mixture through the fuel lines and injectors or carburetor.
• Change the engine oil and gear lube. Old oil contains acids and moisture that can damage internal components over months of inactivity.
• Protect the batteries. Remove them, fully charge them, and store them in a cool, dry location. Use a maintenance charger if possible.
• Winterize all plumbing systems. Drain fresh water tanks, water heaters, and heads. Use non-toxic marine antifreeze in pump lines and holding tanks.
• Treat the interior. Leave cabinets and compartments open to prevent mold. Use moisture-absorbing products like DampRid in enclosed spaces.

Preparing a Fiberglass Boat for Storage

Fiberglass is durable but vulnerable to UV radiation, osmotic blistering, and stress cracks. Your preparation should focus on protecting the gel coat and preventing moisture intrusion.

Key Steps for Fiberglass Boats

1. Wash and wax the gel coat. Use a non-abrasive marine cleaner to remove all dirt, exhaust stains, and waterline marks. Apply a high-quality marine wax or polymer sealant to create a barrier against UV rays and moisture. Do not skip this step, as faded gel coat is more prone to cracking and staining.
2. Inspect for blisters and cracks. Osmotic blisters (small bumps under the gel coat) signal water absorption. If you find any, consult a professional before storage. Small stress cracks should be dabbed with gel coat repair material to prevent water from seeping into the fiberglass laminate.
3. Ensure proper drainage. Remove all drain plugs from the hull, bilge, and livewells to prevent water accumulation. If the boat will be stored outdoors, tilt or block it so the bow is slightly higher than the stern to allow any residual water to run aft and out the drain.
4. Use a breathable cover. Fiberglass traps condensation under non-breathable tarps. Use a fitted, vented boat cover or a breathable shrink-wrap system. Avoid black plastic sheeting, which can trap heat and cause the gel coat to “bake” in sunlight.
5. Support the hull properly on the trailer bunks or blocks. For long-term storage, ensure the hull is evenly supported to avoid stress points that can cause distortion or cracks. If stored on blocks, place them under the stringers where the hull structure is reinforced.
6. Protect all stainless steel hardware. Apply a light coat of marine-grade corrosion inhibitor (like Star brite or Boeshield) to hinges, cleats, and rail fittings. While aluminum boats are more prone to galvanic corrosion, fiberglass boats still suffer from stainless steel pitting in damp environments.

Preparing an Aluminum Boat for Storage

Aluminum is lightweight and corrosion-resistant, but it is susceptible to galvanic corrosion, pitting, and oxidation. Your preparation should prioritize electrical isolation, moisture control, and protecting the unpainted metal surfaces.

Key Steps for Aluminum Boats

1. Wash and rinse thoroughly. Pay extra attention to the bottom and transom areas where trapped mud, sand, or organic debris can hold moisture against the aluminum. Use a mild detergent; avoid harsh acids or alkaline cleaners that can etch the metal.
2. Inspect and clean anodes (sacrificial zincs). Ensure all anodes are tightly secured and not consumed. If they are more than 50% worn, replace them before storage. Without working anodes, aluminum boats develop rapid galvanic corrosion when in contact with dissimilar metals (like a steel trailer or stainless hardware).
3. Address scratches and bare metal. Aluminum oxidizes quickly in air, forming a dull white powder. For painted aluminum, touch up any chips or scratches with marine-grade aluminum primer and paint. For unpainted hulls, apply a marine-grade polish or oxidation remover, then a protective sealant to slow future oxidation.
4. Disconnect all electrical connections. Remove the battery and clean the battery posts. Separate any electrical connections at the hull, such as navigation lights, bilge pumps, and trolling motor leads. Stray electrical currents from a shore power charger or battery maintainer can cause electrolytic corrosion on aluminum components.
5. Prevent moisture entrapment between hull and trailer. Aluminum boats store well on roller trailers, but for bunks, ensure the carpet or padding is dry and not holding moisture against the hull. Consider using small pieces of rubber or PVC pipe to create air gaps under the hull if you expect extended storage.
6. Apply a light protective oil to unpainted aluminum. If your boat has bare aluminum surfaces (common on older fishing boats or jon boats), wipe them with a light coat of silicone-free corrosion inhibitor. Avoid petroleum-based products near the fuel system or rubber components.
7. Cover the boat loosely. Aluminum does not trap condensation like fiberglass, but it can still collect moisture under a tight cover. Use a breathable cover that allows airflow, or tie the cover loosely at the edges to prevent water pooling on top.

Key Differences in Facility Choice for Each Material

The storage facility you select also matters based on your boat’s construction. Fiberglass boats benefit from indoor or shaded storage to minimize UV damage. If outdoor storage is your only option, a premium shrink-wrap service or a top-quality custom cover is essential. Aluminum boats, while more tolerant of sunlight, suffer in humid environments where galvanic corrosion accelerates, so a climate-controlled indoor facility (or at least a dry, well-ventilated space) is preferable for long-term storage. Also, confirm that the facility’s yard does not use gravel or crushed stone that can hold moisture against the hull bottom; paved or concrete surfaces are better for aluminum.

Final Inspection Before Covering

Regardless of material, perform a final walk-through: confirm all drain plugs are removed, windows are secured, hatches are open, and the boat is stable on the trailer or blocks. A quick visual check of the hull for any standing water, cracks, or loose fittings can save you from damage later. Remember that local climate-humidity, temperature extremes, salt air-will dictate how aggressively you need to apply these steps. A boat stored in a dry, inland barn requires less frequent maintenance than one kept near the coast in a humid environment.