daggerboards

Daggerboards are vertical retractable keels used on certain sailboats to provide lateral resistance and directional stability while sailing, and to reduce draft when retracted. They are usually installed in twin configurations, one on each side of the hull, or as a single centerboard on some designs. The blade slides vertically within a trunk through the hull and is raised or lowered by lines or a winch; a pin or clamp locks the board in place. Unlike swinging centerboards, daggerboards do not pivot; they move straight up and down.

When deployed, daggerboards increase lift and lateral resistance, improving upwind performance and stability, particularly in light-to-moderate winds. They also allow the hulls to plane more efficiently by reducing drag when raised. When raised, the boards reduce underwater draft, enabling beaching and navigation in shallow waters. On multihulls, boards on each hull can be operated independently to adjust balance and leeway.

Materials and maintenance: blades are typically aluminum or composite; trunks are glass or fiberglass with seals and guides. Regular inspection of slides, pins, and seals is required to prevent leaks and jammed movement. Safety considerations: ensure boards are fully secured before sailing; check for damage after grounding.

Applications: daggerboards are common on performance dinghies, racing catamarans, and some trimarans, where predictable lateral resistance and shallow draft are advantageous. They are contrasted with centerboards, which hinge or rotate.