Composite materials have been used successfully in marine and offshore applications for several decades. The use of Glass fibre composites (GRP) in marine applications was one of the first significant areas of GRP use. It has revolutionised the industry from a craft-based activity to one of mass production. All variety of boats and vessels can be manufactured using composite ranging from the 'do-it-yourself' dinghies to the latest class of minesweeper with a hull of over 60m in length.
The main advantages of GRP for marine applications are:
- Environmental resistance, including freedom from rotting, corrosion, etc.
- Ability to mould seamless, complex shaped structures
- Ability to tailor strength to suit loading conditions
- Excellent strength to weight characteristics - GRP marine structures generally half the weight of equivalent steel structures.
- Low maintenance and ease of repair
- Excellent durability
Racing yachts use composites more extensively than any other marine structure. The materials used are not typical of marine construction because of special requirements. Minimal weight and maximal stiffness are crucially important in their design so that they can sail with maximal speed and resistance to the impact of waves and other elements in marine environments. Instead of conventional glass fibre reinforced polyester composites, racing yachts are made from advanced polymer composites similar to aerospace materials. Carbon fibre reinforced epoxy composites are usually used in the hull cored with honeycomb or foam, frames, keels, masts, poles and boom, carbon winch drums and shafting. The use of FRPs can contribute to improved performance and minimise the danger of sailing drawbacks and failure in the different international sailing conditions.
The main subsea application of composites has been as protection structures for subsea wellheads and valves. The advantage of using composites is weight saving which can give substantial savings in installation cost through the use of lower cost lift vessels. The cost of manufacture is competitive with that of conventional steel and concrete technology.