Trailer Sailer - Keels

Keels

To be trailable there is a limited number of alternative keels that can be used. In general there is the drop keel or swing keel . For any keel that retracts into the yacht a centreboard case to house it is required inside the yacht. For drop keels full cabin height cases are usually required under safety rules. Swing keel cases can sometimes be kept beneath floors and intrude less into the cabin, but are considered less efficient than a drop keel . Although keels must be locked down when racing, the swing keel has safety advantages for if it runs aground the keel will kick up and either slide over an obstruction or slow the boat, whereas a drop keel will stop a yacht abruptly. A drop keel can be sailed with the board partly raised without upsetting the centre of hull resistance and balance of the boat. A swing keel is a liability for if the yacht capsizes without the centreboard fixed, when inverted the board can swing in and damage the case top, leaving a leak below waterline . To enable sailing with the board partly raised yachts will sometimes carry extra ballast beneath the floors fixed inside the hull, or use a large bulb at the bottom of the board that contains most of the weight. Self-righting tests are sometimes specified for such arrangements.