Yacht Osmosis Survey
Based in Falmouth we provide bespoke yacht osmosis surveys covering Cornwall and the whole of the South West of the UK
About our yacht osmosis surveys
Osmosis treatment for GRP (Glass Reinforced Plastic) yacht hulls involves a process of assessing the extent of moisture ingress sustained by the laminates. The primary objective is to evaluate the level of water penetration and provide expert advice on the most effective method for drying the hull, ultimately restoring the substrate to a strong, fair, and water-resistant condition. Given the complexity of osmotic conditions, there is no one-size-fits-all treatment method for reversing the effects of ingress.
Instead, our approach at Falmouth Marine Surveys is tailored to the specific circumstance of each yacht in order to deliver an optimal marine survey at the end of the process. This undertaking can sometimes be labour-intensive or time consuming and it is important to gain a firm perspective of the hulls condition prior to planning any remediation.
Most hulls built before the mid 1990’s were constructed with Orthophallic polyester resin, this is more prone to ingress into the laminate whereas modern hulls built in the last 30-years are constructed with Isophtalic polyester resin.
Our osmosis treatment service will offer a range of solutions tailored to your budget and timescale, this will begin with the initial recording of moisture levels in the GRP hull. Following this assessment, we carefully monitor the drying process before providing informed recommendations on the application of new coatings that will be up to date with modern products available on the market from manufacturers such as International Gelshield 200, Hempel High Protect II or Coppercoat.
This approach ensures that the treatment aligns with the specific requirements of the job in hand to facilitate an effective and lasting solution. By combining our expertise in moisture level assessments, drying procedures, and re-coating applications, our service aims to bring your GRP yacht hull back to an optimal condition while prioritizing resistance against future concerns with moisture ingress.
Osmosis occurs when water penetrates a boat’s fibreglass hull, reacting with chemicals in the laminate to form acidic fluids. These fluids create pressure, causing blisters and softening the laminate structure. While not immediately catastrophic, prolonged osmosis can degrade the structural integrity of the hull, particularly around high-stress points like the keel, stringers, or bulkheads. Left untreated, it may lead to delamination, reduced hull strength, and costly repairs. Early detection and treatment—such as peeling the gelcoat, drying the hull, and applying epoxy—can prevent further damage. Regular inspections are essential to assess risk and ensure long-term seaworthiness and safety of the vessel.