Ever wondered what causes those annoying fine cracks in gelcoat? And more importantly how do you make them go away? Read on to find out about an easy solution to this age old problem.
What causes gelcoat cracks?Hairline cracks, stress cracks or spider cracks (star cracks) that occur in gelcoat surfaces on fiberglass boats or other water craft are often seen as a cosmetic issue. In most cases this is true, however it is important to seal them correctly otherwise water may penetrate into the fiberglass and cause more serious damage. Most stress cracks occur in the gelcoat layer of fiberglass surfaces and can be repaired by yourself. If structural damage is suspected, you should get your boat inspected by a qualified boat repairer. These problems occur as a result of:
- Manufacturing defects
- Environmental challenges
- Stress and movement
- Swelling of the resin due to water diffusion
- Wave action and rigging stresses
- Direct sunlight or thermal shock on darker colored gelcoat can cause warping, delamination and blistering
- Expansion or contraction
How do you tell what the cause is? By the pattern of the crack:
- Radial cracks (spider cracks, star cracks) – caused by impact or by a fixture / bolt that puts strain on a certain area of a boat and cracks occur around the hole.
- Linear crack – caused by flexural strain
- Thermal fatigue cracks – when gelcoat repeatedly expands or contracts. These might be in a parallel pattern or a non-directional pattern