Osmosis Treatments

Osmosis is a common issue for older GRP hulls, but can also occur in newer boats under certain conditions. It is caused by water penetrating the gel coat and breaking down the laminate over time. 

If left untreated, it can lead to blistering, softening of the laminate, and eventual structural damage. We can offer full-service osmosis treatment—from early-stage blistering to more advanced delamination.

Every job starts with a proper inspection to determine the extent of the problem. Once assessed, we mechanically strip back the affected areas and remove moisture-contaminated laminate. 

A substantial drying period may be required depending on the extent of the damage and the moisture content within the hull. We can make visits to monitor progress and advise when the hull is ready for rebuild and recoating.

All rebuild materials are selected to match the original layup and the structural demands of the area being repaired. For smaller or superficial repairs, we typically use chopped strand mat on its own. 

In cases of more severe delamination or structural damage, we use a combination of CSM, biaxial cloth, and woven roving, laminated with marine-grade epoxy or polyester resins, depending on compatibility with the existing hull. 

This approach ensures proper bond strength, structural integrity, and long-term durability—whether we're reinforcing flat sections or rebuilding curved areas of the hull. 

Once the repair work is complete, the hull is faired and prepped for coating. We apply a robust epoxy barrier system—such as International’s Gelshield or equivalent—to seal the hull and protect it from future water ingress.

We don’t rush drying times or take shortcuts on materials. Osmosis repair is structural work, not just cosmetic, and we treat it with the care it deserves.

Whether you're dealing with a few isolated blisters or full hull treatment, we carry out the work methodically to ensure your boat is properly restored and ready for the long haul.