Composite materials for marine use

Currently, many markets are benefiting from advances in composite materials, but perhaps none have benefited more than the leisure and commercial marine industries. Building ships that can meet the demanding requirements of water environments, especially salt water environments, has always been a challenge. Life at sea means constant exposure to harsh environments, including direct sunlight, wind and water pressure, the corrosive effects of salt water, and human factors such as diesel fuel, lubricants and other chemicals.

Composite materials offer some of the best solutions to the problems caused by these marine conditions. From stronger FRP (fiber reinforced polymer) hulls and interiors, to corrosion-resistant marine components, to specialized submersible components, marine composites have revolutionized everything possible.

The impact of marine composites on the marine industry is most evident and can be observed under the hull, deck and interior of most recreational and commercial boats in production today. The use of composite materials, including glass fiber, carbon fiber or glass/carbon hybrid composites, can be found almost everywhere. Classic wooden boat building will never go out of style, but commercial production of FRP hull boats has increased substantially since the 1950s. While some people prefer aluminum and fiberglass hull construction for certain boats (particularly shallow-water riverboats), overall, fiberglass composites offer the widest range of design and style options, as well as the most comfortable ride.

When it comes to seawater-resistant engineered components, composites definitely have advantages over conventional materials. Composite materials for marine use can be customized to: resist corrosion, withstand deep water pressure, provide a watertight seal, and meet many other special requirements. For example, many traditional rubber parts that were once used as marine gaskets are now being made from stronger composite materials. The same goes for components of marine engines and pumps. As the marine industry continues to push for more energy-efficient engines and better prefabricated components, the reliance on composites to improve efficiency is increasing.

Composite materials have been used in the marine industry for many years. More traditional applications of composites include gratings, pipes, shafts, ship hulls, etc. for decades. But wood and reinforced concrete are still used in marine applications as traditional technologies.

Marine composite:

--Reinforced concrete

Reinforced cement was probably the earliest composite material used in the marine industry to develop low-cost barges. The steel frame formed by the rebar is covered with barbed wire and is used as a "formwork", by pouring cement around the formwork to form the hull. It is then plastered with wire mesh and then cured. Although it is an inexpensive composite material, armature corrosion is a common problem in chemically aggressive marine conditions. Today, some iron ships are still in use.

-- Fiberglass reinforced plastic

Fiberglass was introduced after polyester resins were developed. Soon, glass reinforced plastic boats have been around since the early 1950s and continue to be an important composite construction technology in marine applications today.

Fiber-reinforced polymer composites (FRPs) have been successfully used for decades in marine applications such as radomes and mass structures, superyachts, work boats and recreational boats. More recently, FRPs have been used in lesser-known applications such as bearings, propellers, commercial hatch covers, exhaust and superdeck structures. The use of glass fiber composites (GRP) in marine applications is the first significant area of GRP use. It has revolutionized the ability to design and manufacture large composite structures in several sectors. Boats are built through a variety of processes, including hand-laid GRP, resin infusion, thermoplastic and high-performance carbon fiber prepreg racing yachts.

-- Wood/adhesive composites

Wartime demands led to the development of "hot form" and "cold form" shipbuilding techniques based on laying veneer veneers on the frame. On the other hand, high-performance urea binders are also widely developed for forming ship hulls and aircraft manufacturing to help speed up the production process and reduce reliance on aluminum and steel.

-- Aramid fiber composite material

Aramid fibers are widely used to strengthen sailboat structures such as the keel and bow sections. In addition, the aramid fiber composite has improved shock absorption properties, making it ideal for marine racing applications.

For example, the performance of Kevlar marine composite materials is very good. In marine composites and marine marine composites, Kevlar helps provide the ideal balance of strength, stiffness and lightweight properties for many marine applications. In patrol boats and service boats, higher speeds can be achieved by increasing engine power - an option that can be quite expensive. Another approach is to reduce weight by incorporating Kevlar reinforcement into existing laminate structures or new designs. DuPont helps ship hulls reinforced with Kevlar fibers to be lighter, tougher, more damage-resistant, and perform better under hydrodynamic fatigue loads.

The use of aramid fibers in recreational and racing galleons, sailing and motor boats has gained wide acceptance in the racing world. Sailing's prestigious events such as the America's Cup, Glove Challenge, and Whitbread Cup, as well as powerboats for numerous maritime world championships, attribute their success to the use of aramid fibers in the construction of the hull and superstructure. If speed is the main criterion for using advanced composites, their resistance to harsh environments is a close second.

--Carbon fiber

Carbon fibers are increasingly used in sailboats, furniture and high-strength interiors on superyachts, as they provide boat stability benefits and high performance with minimal weight. Carbon fiber is also seen as a fashionable material that is often replaced not only for its superior material properties, but also for the aesthetic component of woven materials.

Rowing boats use composite materials more extensively than any other marine construction. Due to special requirements, the materials used are not typical marine construction materials. Minimal weight and maximum stiffness are critical in their design so they can travel at maximum speed and resist the effects of waves and other factors in the marine environment. Carbon fiber reinforced epoxy composites are commonly used in honeycomb or foam core hulls, frames, keels, masts, poles and arms, carbon winch drums and shafting. In different international navigation conditions, the use of FRPs helps to improve performance and minimize the risk of navigational obstacles and breakdowns.

In luxury yachts and larger vessels of 96 feet or more in length, the hull and superstructure weight is a smaller percentage of the total weight than a patrol or service boat. Larger boats still need to be built at a minimum weight or within certain weight limits. In this case, however, weight reduction is usually to achieve an increase in speed, or to improve fuel economy, to increase payload, or to reduce weight to carry more accessories. Carbon fiber can be very effective as construction hulls, such as superstructures, bulkheads, and furniture, helping to make them both tough and durable.

-- Underwater application

The main subsea application of composites is as protective structures for subsea wellheads and valves. The advantage of using composite materials is that they are light weight, which can lead to significant savings in installation costs through the use of lower cost lift boats. Manufacturing costs are competitive with traditional steel and concrete technologies.