When it was first used in boat hull manufacturing fibreglass was immediately touted as a miracle building material that reduced the price of boat-building into the affordable range. The first fibreglass boats began being sold on mass as early as the 1960s. Earlier models existed as far back as the 1930s but commercial success began 30 years later.


Fibreglass can and does suffer from age, elements, and wear and tear. This process of breakdown is the result of cracking. The deterioration initially seems minor, with microscopic cracks in the formed fibreglass fabric. Over time, these cracks get bigger, separating fibres and the resin that hold them together. The bigger the cracks get, the more stress occurs to the remaining material. Eventually, a significant break occurs when the integrity can no longer hold together. Boat owners have to regularly monitor their fibreglass boats for these cracking problems and fill them in when found.


Boat hulls are exposed to two categories of stress: vibration and impact from the ocean. Impact tends to cause the greatest damage over time, especially from the constant and regular slapping of waves against the hull. Working boats, such as fishing units, also carry significant strain due the equipment they operate and the pulling involved with fishing net weight, etc. Fatigue cannot be avoided; it can only be addressed when weakness signs start to show strain on a boat hull.

Fibreglass hulls tend to also suffer aggregate stress over time from fatigue, studies have shown that fibreglass hulls will lose their rigidity against the outside ocean with the weakness growing gradually. This basically means that such hulls have a set utility life and then are no longer safe, period.


Generally, the resin used tends to be waterproof. But once water gets in, its corrosive nature begins to enhance the damage. Over time, the boat hull absorbs moisture, which causes penetration to expand further. This damage occurs below the waterline of the hull where the boat is constantly exposed to the ocean. Waterproof painting of the hull can help fend this off, but barnacles and the water eventually break through such a thin barrier. Eventually, blistering occurs as moisture creeps between resin layers. Drilling into the hull for fixtures only adds to the problem as water then entered through the drill holes as well.


The foams and plastic composite used inside fibreglass for hull rigidity don’t do well under intense heat. The direct sun temperature can reach over 65 C on white colour. Black can double the surface temperature. This cooking eventually begins to warp fibreglass cores, regardless of being inside fibreglass layers. Once distorted, the cores cannot be repaired.

If you think you have signs of fibreglass fatigue on you boat or Jet Ski give us a call for advice.