Fiberglass hull blistering, often called “osmosis,” is a common problem affecting boats kept in the water. Osmosis occurs when water penetrates the gelcoat and reacts with uncured resins or contaminants, producing acidic fluids that create pressure pockets.

Blister symptoms include:

• Raised bumps on the hull surface
• Soft or spongy laminate around blistered areas
• Cracked or crazed gelcoat
• Fluid weeping from blisters with noticeable odor when punctured

If left untreated, osmotic blistering spreads, weakens fiberglass laminates, and devalues the boat.

Captain Dave and Captain Levi repair fiberglass osmosis blisters by:

• Grinding out all blisters to solid laminate
• Thoroughly drying hulls to prevent recurrence
• Rebuilding with epoxy or vinyl ester resin and fiberglass fabrics
• Fairing with epoxy filler for smooth, fair surfaces
• Applying barrier coats to protect against future osmosis penetration
• Spraying protective finishes, wet sanding, and buffing to restore yacht‑quality gloss

Professional blister repair restores structural strength and preserves boat value. With proper barrier coating, blister damage is permanently stopped.

From our Largo, Florida shop and boat yard, Captain Dave and Levi dispatch mobile crews to customers throughout:
Belleair, Belleair Beach, Belleair Bluffs, Belleair Shore, Clearwater, Dunedin, Gulfport, Indian Rocks Beach, Indian Shores, Kenneth City, Largo, Madeira Beach, North Redington Beach, Oldsmar, Pinellas Park, Redington Beach, Redington Shores, Safety Harbor, St. Pete Beach, St. Petersburg, Seminole, South Pasadena, Tarpon Springs, Treasure Island, and Tampa.