Osmosis Repair
In this article we explain what osmosis is in GRP boats, how it forms, diagnostic methods, full repair procedure and epoxy barrier coating for permanent protection.
1. What Is Osmosis?
Osmosis is a slow water-permeation damage in fibreglass (GRP) boat hulls. Hygroscopic substances within the laminate draw water molecules into the hull through osmosis. Over time, pressurised water pockets form under the gelcoat, creating blisters. Left untreated, osmosis can reduce structural strength by over 50%.
Minimum drying period for complete osmosis repair
Standard number of barrier epoxy coats
Laminate strength loss from untreated osmosis
2. Repair Process
Moisture measurement (moisture meter; above 4% is suspicious) → blasting/grinding to sound laminate → controlled drying (minimum 6–12 months) → laminate repair with epoxy and fibreglass → 5 coats of epoxy barrier coating (each coat fully cured) → antifouling → guaranteed delivery.
⚠ Critical: Insufficient Drying
If epoxy is applied before the laminate is sufficiently dry, the moisture trapped beneath creates a new osmosis cycle. This is the most common cause of osmosis repair failure.
3. Conclusion
Osmosis repair gives permanent results when performed with correct technique and sufficient drying time. DR.YACHT guarantees all osmosis repairs with moisture measurement documentation and epoxy barrier application.
Service Summary
- Duration PROJECT-BASED
- Warranty 2 - 5 YEARS
- Location SHIPYARD / MARINA
- Standard ISO 12944
Technical Support
Let us determine the most suitable technical method and material selection for your project.
0538 357 86 88