Abstract: Disclosed ia a keel for a sailing boat having a hydrofoil section. The thickness to chord ratio of the keel increases from the top to the bottom creating a vortex trap and thus reducing the drag of the keel. A generally horizontal plate at the bottom of the keel is also disclosed and further reduces the drag induced by vortex shedding. In one form the camber of the keel is adjustable. The mechanism for adjusting the camber includes rotatable forward and aft sections faired to a center section of the keel by sheets with a length being a small portion of the total cordal length of the keel. The fairing sheets are fixed along one vertical edge and tensioned by rods located within the rotating forward and aft sections of the keel.

Abstract: An outboard computer system which combines the outputs from onboard course, performance and wind measuring instruments to determine a sailing vessel's instantaneous rate of progress to windward when beating. This information is then used to produce audible and/or visual signals indicating to the crew when the optimal track and sail setting for the conditions has been attained, enabling them to beat optimally under the current ambient conditions. The system is also used to control automatically the settings of each of the sailing variables: rudder, main sheet, traveller, jib sheet, etc. in order to sail the vessel optimally when beating without the intervention of the helmsman or crew. A facility is also provided for recording the instantaneous rate of progress to windward in coincidence with any other variables of interest for the purpose of post evaluation and assessment of a variety of boat related equipment and procedures. The system also provides displays relating to wind history and wind prognosis.