Glass Reinforced Plastic:
GRP is the mainstay of production boat construction through out the world. First introduced in the 1950's GRP is arguably the most forgiving of all construction mediums.
GRP can have a number of problems that usually stem from poor construction techniques, and some manufacturers still manage to repeat the problems on a regular basis.
During the 1970's and 1980's a large number of boats were built. Some were built without a full understanding of GRP construction requirements and have proven to be expensive to repair, as hull and deck cores became saturated and laminates blistered.
Some new boats are becoming harder to survey due to the use of inbuilt liners, which make the internal structure of the boat almost impossible to access. Surveyors are constantly challenged by the builders of these boats who insist on a 'fit and forget' method during construction.
A common fault in production craft is the use of 'flo-cote' as a coating over plywood. This product is not waterproof and any areas subject to wet and dry cycles such as bilges or cockpit lockers can have rot issues.
The repair of cored hulls can present some cost barriers if damaged by water. Balsa core can rot very quickly if left wet and any older GRP balsa cored hull needs to be checked thoroughly for moisture ingress.
Cored decks can also be expensive to repair and decks are often damaged from water entering the core from deck fittings that have not been bedded correctly or have not been maintained.