Osmosis Treatments & Hull Coatings

Protection below the waterline

Osmosis is a problem that develops in a GRP hull that is immersed in water long-term. The main symptoms are blisters over the affected hull surface, which when opened or pierced give a smell of vinegar or acetic acid. There is no real benefit in attempting to treat small localised areas. The solution lies in removing the outer barrier layer (the gelcoat), drying the underlying laminate and actively removing the chemicals that have drawn moisture through the gelcoat barrier. Finally, reinstating the outer barrier with a specifically developed epoxy coating system that is superior to gelcoat in terms of moisture protection and adhesion to the hull surface.

In some cases there may be a requirement for the replacement of laminate that has been damaged/previously removed or for the application of additional laminate to the existing hull layup, either over the entire hull surface, or locally. This process is carried out under closely monitored and recorded conditions using the best materials and techniques.

The filling/fairing process completes the surface preparation prior to the application of epoxy barrier coats, usually Hempels Gelprotect SFE200.

Once this has been completed, the hull is then ready to re-apply your choice of antifouling system.

There is a huge choice of antifouling paint to choose from, we usually use Hempels products and have found them to be excellent performers in the local area.
Coppercoat™ is an epoxy based antifouling system that has a number of benefits – additional epoxy barrier to resist future moisture ingress, no seasonal re-application tasks, smooth surface for better hull speed and fuel economy; the list goes on. Frequently, after an osmosis treatment is the time (economically) to apply Coppercoat™ to your hull. When the surface preparation has already been done, the Coppercoat™ itself provides a superb hull finish.

Steel or wooden hulls obviously are not prone to osmosis. They do however have their own issues relating to corrosion of material, fixings or rot and these concerns need to be inspected and assessed in some detail before a course of action is proposed. Never-the-less, we have the facility and resources to carry out most kinds of repair work in timber and steel on site. If the boat can be transported to us, we can fix it…

Osmosis Treatments and Hull Coatings Osmosis Treatments and Hull Coatings