Boat

For other uses, see Boat (disambiguation).

A boat is a craft or vessel designed to float on, and provide transport over, water.

A boat's propulsion can be by propellers, oars, paddles, setting poles, sails, paddlewheels, or water jets. Boats are generally smaller than ships.

A wooden boat operating near shore.

Parts of a boat

A boat in an Egyptian tomb painting from about 1450 B.C.E.

The roughly horizontal, but cambered structures spanning the hull of the boat are referred to as the "deck". In a ship there are often several, but a boat is unlikely to have more than one. The similar but usually lighter structure which spans a raised cabin is a coach-roof. The "floor" of a cabin is properly known as the sole but is more likely to be called the floor. (A floor is properly, a structural member which ties a frame to the keelson and keel.) The underside of a deck is the deck head.

The vertical surfaces dividing the internal space are "bulkheads". The front of a boat is called the bow or prow. The rear of the boat is called the stern. The right side is starboard and the left side is port. Many boats have a section called the gralper, designed to reduce water flow to the non-hydrodynamic parts of the boat.

Types of boats

A passenger boat to the islands off the coast of the Sai Kung Peninsula of Hong Kong.

A sailboat (racing dinghy) and barge share the Mississippi River, USA.

Air boat Banana boat Bangca Bareboat charter Barge Bow Rider Cabin cruiser Canoe Cape Islander Car-boat Caravel Cargo Boat Catamaran Catboat Coble Center Console Coracle Cruiser Cuddy Cutter (pulling boat) Cutter (sailing boat) Dhow Dinghy Dory Dragon boat Dredge Durham Boat Dutch Barge Express Cruiser Felucca Ferry Fireboat

Fishing boat Folding boat Go-fast boat Gondola Houseboat Hovercraft Hydrofoil Hydroplane Inflatable boat Jangada Jetboat Jet ski Jon boat Jordan Sales Junk Kayak and Sea kayak Ketch Lifeboat Log boat Longboat Luxury yacht Motorboat Narrowboat Norfolk wherry Outrigger canoe Padded V-hull Panga Personal water craft (PWC) Pinnace Pirogue Pleasure craft Pontoon Powerboat Punt

Raft Rigid-hulled inflatable boat (RHIB) Riverboat Runabout Rowboat, rowing boat Sailboat, sailing boat Sampan Schooner Scow Semi-dory Sharpie Shikaras Ship's tender Ski boat Skiff steam boat Sloop Submarine Surf boat Swift boat Tarai Bune Tjalk Trimaran Trawler (fishing) Trawler (cruising) Tugboat U-boat Waka Wakeboard boat Walkaround Water taxi Whaleboat Yacht Yawl

Unusual boats have been used for sports purposes - for example, in "bathtub races" which use boats made from bathtubs. Pumpkins have been used as boats as in the annual Pumpkin Boat Race on Lake Otsego in New York state, USA. In this race, very large, hollowed out pumpkin shells are used for boats, powered by canoe paddles.

Boat building materials

A ship's lifeboat, built of steel, rotting in the wetlands of Folly Island, South Carolina, USA.

Until the mid 19th century all boats were wooden. As the forests of Britain and Europe continued to be over-harvested to supply the keels of larger wooden boats and the Industrial Revolution cheapened the cost of steel, the age of the steel ship began. In the mid 20th century aluminium gained popularity, being lighter and easier to work with than steel. Around the mid 1960s, boats made out of glass-reinforced plastic, more commonly known as fiberglass, became popular, especially for recreational boats. The coast guard refers to such boats as 'FRP' (for Fiberglass Reinforced Plastic) boats.

Fiberglass boats are extremely strong, and do not rust, corrode, or rot. Fiberglass provides structural strength, especially when long woven strands are laid, sometimes from bow to stern, and then soaked in epoxy (i.e., plastic) to form the hull of the boat. One of the disadvantages of fiberglass is that it is heavy and to alleviate this, various lighter components can be incorporated into the design. One of the more common methods is to use cored fiberglass, with the core being balsa wood completely encased in fiberglass. While this works, the addition of wood makes the structure of the boat susceptible to rotting. Similarly, 'advanced composites' are simply other methods designed to introduce less expensive and, by some claims, less structurally sound materials.

Severn class lifeboat in Poole Harbour, Dorset, England. This is the largest class of UK lifeboat at 17 metres long

Boat propulsion

The most common means are:

• Human power (rowing, paddling, setting pole etc.)
• Wind power (sailing)
• Motor powered screws
  • Inboard
    • Internal Combustion (gasoline, diesel)
    • Steam (Coal, fuel oil)
    • Nuclear (for LARGE boats)
  • Inboard/Outboard
    • Gasoline
    • Diesel
  • Outboard
    • Gasoline
    • Electric
  • Paddle Wheel
  • Water Jet (Jet ski, Personal water craft, Jetboat)
  • Air Fans (Hovercraft, Air boat)

Why boats float

See also buoyancy

A boat stays afloat because its weight is equal to that of the water it displaces. The material of the boat itself may be heavier than water (per volume), but it forms only the outer layer. Inside it is air, which is negligible in weight. But it does add to the volume. The central term here is density, which is mass ('weight') per volume. The mass of the boat (plus contents) as a whole has to be divided by the volume below the waterline. If the boat floats than that is equal to the density of water (1 kg/l). To the water it is as if there is water there because the average density is the same. If weight is added to the boat, the volume below the waterline will have to increase too, to keep the mass/weight balance equal, so the boat sinks a little to compensate.

External links

• Hull Identification Numbers Explanation of International HIN formats
• University of Washington Libraries Digital Collections — Freshwater and Marine Image Bank — Vessels Images of boats and vessels.

Credits

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