Stopping that sideways movement through the water
A centerboard is a pivoting plate of wood or metal that is lowered into the water through a slot along the centerline of a sailboat. Its main purpose is to prevent the boat from being blown sideways, but you can also use a center-board to balance the helm by partially lowering or raising it, which moves the hull’s center of lateral resistance (CLR) forward or aft. If the centerboard is made of thick, heavy metal, it may also contribute to the boat’s stability.The centerboard is housed in a narrow case, or trunk, that necessarily protrudes into the footwell of a dinghy or the accommodation of a yacht. It is often used in place of a fixed keel on small sailboats to allow them easier access to a road trailer. Designers

Centerboards (pivoted) and daggerboards (sliding) stop sailboats from being pushed sideways by the wind. Weighted boards also act as ballast to aid stability.

also use the centerboard on craft used to explore shallow waters, where a deep fixed keel would make navigation impossible, or on boats used for sail-camping that are drawn up on a beach at night. There are also hybrid keel-centerboard designs in which a centerboard is housed entirely within a comparatively shallow keel and lowered when additional sailing efficiency is needed.On sailing dinghies, the pivoting centerboard is usually raised and lowered by hand, although a steel plate may require the use of a small tackle. Invariably, on larger boats, some form of block and tackle or mechanical device is used.Very small boats, say those 10 feet in length or less, mostly use daggerboards in place of center-boards. A daggerboard has no pivot and simply slides up and down in a close-fitting case, or trunk.See also Block and Tackle; Leeboards.

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