Boat building
Boat building is one of the oldest branches of engineering and is concerned with constructing the hulls of boats and, for sailboats, the masts, spars and rigging.
Part of a boat
Each part of the hull has a different name and purpose:
- bow - the front and generally sharp end of the hull. It is designed to reduce the resistance of the hull cutting through water and should be tall enough to prevent water from easily washing over the top of the hull
- chines - are long, horizontal strips on hydroplaning hulls that deflect downwards the spray that is produced by the hull when it travels at speed in the water
- deck - the top surface of the hull keeps water and weather out of the hull and allows the crew to stand safely and operate the boat more easily
- gunwhale - the sides of the hull are mostly concerned with preserving the buoyancy of the hull by keeping water out
- keel - the main central member along the length of the bottom of the boat. It is an important part of the boat's structure which also has a strong influence on its turning performance and, in sailing boats, resists the sideways pressure of the wind
- keelson - an internal beam fixed to the top of the keel to strengthen the joint of the upper members of the boat to the keel
- rudder - a steering device at the rear of the hull created by a turn-able blade on a vertical axis
- stem - a continuation of the keel upwards at the front of the hull
- transom - a wide, flat, vertical board at the rear of the hull, which, on small boats, is often designed to carry an outboard motor
Construction materials
A wide variety of materials are used in boat building:
- wood - the traditional boat building material that was and is still used for hull and spar construction. It is buoyant, cheap, widely available and easily worked. It is not particularly strong and it deteriorates if water is allowed to penetrate the wood. Glue, screws and nails are used to join the wooden components.
- steel and before that iron - either used in sheet for all-metal hulls or for isolated structural members. It is strong. The material rusts unless protected from water. Modern steel components are welded or bolted together. Until the mid 1900s, steel sheets were riveted together.
- aluminium - either used in sheet for all-metal hulls or for isolated structural members. Many sailing spars are made of aluminium. The material requires special manufacturing techniques, construction tools and construction skills.
- glass-reinforced plastic (GRP) composite - used to create a smooth and hydrodynamically efficient hull shape.
- steel-reinforced concrete - strong but heavy and prone to internal corrosion. It is not often used for boat building.
Construction methods
There are several hull construction types:
- clinker - overlapping wooden planks are attached to a frame.
- carvel - a smooth hull is formed by wooden planks are attached to a frame.
- GRP mould - glass reinforced plastic is moulded into a hull shape.
- inflatable boat - the hull is created from rubber air-tight tubes that are inflated with high pressure air. For simple inflatable boats, the flooring often consists of plywood or aluminium sheet. For rigid-hulled inflatable boats, the flooring is part of the GRP hull.
- lapstrake - planks are fixed to each other and then a frame built inside the hull.
- plywood - sheets of plywood are fixed to a frame built forming a smooth hull.
- stitch-and-glue - pre-shaped panels of plywood are edge glued and reinforced with fibreglass without the use of a frame.
- strip-built - thin, flexible lengths of wood are secured together and reinforced with fibreglass.
See also sail, sail-plan, ship building, outboard motor, propeller
