Drop keel for yachts, partic. large ones - is constructed as an independent pre-stressed structure, usable at various depth settings

摘要

The drop keel unit comprises a ballast weight (9) suspended from a retractable structure made up of a centreboard (10), a flat rectangular extension to this (which may be a framework only, to minimise windage effects and interference with vision when the unit is raised) both of these being stiffened against bending/buckling, and tensioned wires (11, 11', 12, 12') run over spreaders (13) at each end to provide further stiffening. A deep box (15, 15') connected to but only interrupting the bottom (17, 17') and top (16, 16') fore & aft strength members houses the unit and embodies guide rails for the pintlers (23, 24) transmitting the centreboard loads to the hull. Raising and lowering is by (wire) ropes and winches the unit can be locked in place to unload the winches.