Gelcoat A boats gelcoat is the top ply of the fiberglass hull. It is the ply of pitch that serves as protection for the hull. The gelcoat is applied to moulds in the fluid state. Thus the fiberglass is protected from the water, moisture or the ultraviolet rays of the sun. Thanks to the effects of the gelcoat, the boat receives its color. It also gives the boat a glossy finish. The composition of the gelcoat is made up of OMC outdrive parts and unsaturated polyester resin chemistry. Both sea-going ships and OMC outdrive parts are produced by using composite materials. The top ply is usually a gelcoat. Its thickness makes up about 0.5mm - 0.8mm. Gel coats are intended to be solid and durable, being resistant to hydrolysis and ultraviolet rays. However it is worth mentioning that severe marine conditions can cause damage on the gelcoat. The negative influence on the gelcoat is particularly caused by the sun ultraviolet rays as well. In this case you may be faced with ...