boat factory

GRP shipbuilding

Most of today’s yachts and boats are built with fiberglass reinforced plastic (GRP). This strong, resilient material is a combination of a resin (which is manufactured to be chemically hardened or set) and a strong reinforcing material, usually glass fibers, giving the material its common name fiberglass.

The resin can include polyester, solvents, catalysts, and other additives. Reinforcement is fiberglass cloth (a smooth woven fabric), roving (a coarse, basket-like woven fabric), or mat (a random combination of many short fiberglass strands).

Production begins with the formation of a smooth female mold (usually made from GRP laminate) over a precision built wooden plug, which establishes the shape of the hull. The color of the helmet is established by means of gelcoat resin, sprayed against a release agent, previously applied on the surface of the mold.

The glass and resin are then combined in a hand-laying process to produce the hull structure. The thickness can vary according to the composition and the number of layers and is determined by the correct compromise between resistance and lightness required in the different sections of the hull. The cover is produced in the same way.

From then on, the real skill lies in equipment. This includes the construction of bulkheads (transverse hull reinforcement panels), interior carpentry and the correct connection of all GRP, wood and metal elements. ‘Sandwich’ construction involves GRP laminates enclosing a closed cell foam core or balsa wood. This provides a stiffer structure, weight for weight, but has reduced impact resistance. Fittings must be carefully attached to sandwich hulls and decks to prevent water from seeping in and degrading the core.

More and more advanced materials are entering the boat building trade. Epoxy resins and graphite-aramid fibers such as KevlarTM, carbon and other new reinforcements promise remarkable structural strength, stiffness and weight efficiency.

wooden boat building

Since the beginning of time, wood has been the traditional material for boat building. Ancient ships, and until the 19th century, commercial and warships, were built with wood. Interest in yachting and speed sailing led to lighter but solidly built and carefully designed wooden structures. Even 100-year-old yachts, if properly designed, built, and cared for, can still be repaired.

Carvel has always been the most common form of wood construction. Typically, a steam bent skeleton of oak is formed to support the planks from stem to stern. These are made from light wood in small boats and from harder woods, such as elm, in larger vessels. The joints between the planks are filled with putty to waterproof the structure.

Clinker/lapstrake construction, common for small boats in the past, is a method in which relatively thin molded planks overlap each other at the joint. Mechanical fasteners (often copper rivets) join the edges of the planks together, both to seal against leaks and to secure the shell to the internal bracing pieces.

A smoother finish can be achieved by using a molded wood construction, which involves manufacturing a single unit of glued plies for the entire hull.

Wooden boat building has had something of a renaissance in recent years with increasing numbers of people rediscovering the joys of the more traditional craft. Complete with rigging derived from the workboats of yesteryear, the original construction techniques are enhanced with the use of modern materials such as epoxy resins to increase strength and, perhaps most importantly, reduce maintenance while maintaining good looks.

The choice of good construction materials and a perfect fit between the members are essential for the durability of the yachts. Quality construction will go a long way in preventing water ingress and rot.

metal boat building

The strength and durability of metal construction are attractive, especially for larger yachts. Except in the case of small boats, traditional steel or aluminum riveted joints have given way to welded hulls.

Two types of hull structure are possible. The transverse structure involves curved, angled or T-section reinforcements within the hull in the same pattern as the conventional structure of a traditional wooden hull. The longitudinal framing extends forward and aft, supported by bulkheads.

Welding is initially used to join shaped and curved hull plates to the frame grill and to position the edges of the plates together. Welding passes are then made to fill all ends and seams, for hull strength and watertightness. Additional selective welds are made to ensure a satisfactory connection of the hull skin to the structure and reinforcements.

During welding, shrinkage of the weld metal as it cools is a critical problem for the final shape. Therefore, a proper welding sequence, from port to starboard and from deck to keel, must be followed on the skin to avoid distortion of the yacht’s shape from the desired geometry and to avoid build-up of internal stresses, that can limit the external load. load capacity of the hull structure.

Skillful lofting (the full-size drawing of the hull shape lines, precise frame formation and configuration) plus proper welding sequence can achieve a reasonably smooth and accurate hull surface. However, for a proper yacht quality hull surface, a coat of fairing compound over the metal skin is required. After a primer coat to inhibit corrosion and ensure proper adhesion, the filler material is troweled and finally hand sanded to the desired precision and smoothness using long, flexible sanding boards. Conventional or spray polyurethane paint coating finishes the job.

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