Title: Improvement of the speed and safety of sailboats using canting keels
Grade level: high School - Grades 10-12
Academic Level: Ordinary
Project Type: Experimental
Awards: Google Science Fair 2011 finalist
Affiliation: Google Science Fair
Equipment, Materials and Techniques: Remote control ship model, 3 hp. 160 GPM pump, force sensor, flow meter, digital scale, computer with Vernier LabPro, Strait Line Laser level 120.
Description: An external adjustable ballast system for keeled sailboats comprising a weight that is designed for low hydrodynamic drag, mounted through a beam to a shaft running down the leading edge of the fin keel. Turning the shaft moves the weight to optimize hull trim, both fore/aft and athwartships, for a particular point of sail. If the weight and beam are shaped as a lifting body and mounted to the shaft such that it pivots as it rotates to optimize angle of attack, the dynamic balancing component can allow for a lighter weight. Ballast weight and beam can be raised or lowered to optimize performance for expected wind conditions. The leading edge of the fin keel is a rotatable non spherical shaft. When rotated, the shaft creates an asymmetric cross section which improves hydrodynamic efficiency of the keel. (Patent 7513205)
A canting keel is a form of sailing ballast, suspended from a rigid canting strut beneath the boat, which can be swung to windward of a boat under sail, in order to counteract the heeling force of the sail. The canting keel must be able to pivot to either port or starboard, depending on the current tack.
The current canting keel technology is far from perfect. At least three of the seven boats in the 2006 Volvo Ocean Race, one of the first major long term races allowing canting keels, had problems with the keels. One area in particular, the plates sealing the opening through which the keel passes, are prone to leaks. Unlike a centerboard or daggerboard trunk, the opening for a canting keel must allow significant lateral motion, which requires sliding seals.
The boat movistar had problems on Leg 4 of the Volvo Ocean Race, 200 miles off Cape Horn, during the night on 2 March 2006. It sprung a significant leak when the sliding plates that covered the keel opening fell off in the middle of the night. This was a problem that had occurred earlier. movistar's aft keel pivot broke loose and began flooding the boat. They made repairs in Ushuaia on the Beagle Channel. Later on, in Leg 7 the same problem occurred in the north Atlantic. This time the decision was made to abandon ship, and the crew transferred to ABN AMRO TWO. movistar continued to broadcast its position for several days, but an aerial search failed to find the vessel, and it was lost.
In the 2006/2007 VELUX 5 Oceans Race (a single-handed, round the world race), the Open 60 yacht Hugo Boss, skippered by Alex Thomson, had to be abandoned in the Southern Ocean due to the snapping of the hydraulic rams that controlled the keel, which caused the catastrophic failure of the keel. When this failure caused the yacht to nearly capsize, the boat was abandoned; Thomson was rescued by fellow competitor Mike Golding. On the 25th November 2006, the boat's Sat C transponder stopped transmitting, and the hull has to date not been salvaged.
Movable ballast in a sailing vessel (US Patent 7513205)
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