What is Twin keel?

Twin keels or bilge keels are two keels that emerge at an angle from the hull of a sailboat , at or near the bilge. The angle allows the boat to have a shallower draft while still allowing for minimum leeway while sailing. The placement of the twin keels also allows the boat to stand upright when out of the water without additional support, as opposed to a single-keeled boat that would fall over if water levels dropped. Twin-keeled boats are typically used in coastal areas that experience extreme changes in tide. When the tide is low, the boat will sit on her keels and remain stable and upright. This configuration is especially useful for sailors in Britain and might in the future be applied in the parts of the Atlantic North America that are extremely tidal such as the Fundy waters that are shared by Maine, New Brunswick, and Nova Scotia.

Twin keels are meant to make sailing safer and easier in shallow or extremely tidal waters while preserving the stability and performance of deep-keel vessels. Yet, twin keels are often shown to provide better theoretical performance on paper, and, in reality, are only slightly slower performing when compared with single keels on identical vessels. They are also said to be safer in downwind conditions as they are more resistant to rolling, and hence should not broach as easily.