The latest reported keel loss of a sailing yacht has been analysed by an award-winning journalist for the leading US yachting journal, Sail. Ran Tan II lost her keel in mid-Pacific in May last year and her three crew were rescued from a life-raft.
Journalist Rebecca Hayter interviewed the 50ft Elliot race yacht’s designer, Greg Elliot and also a leading expert on design, Andy Kensington. Elliot revealed the lifting keel had been modified to a canting keel.
Kensington, consultant with the America’s Cup defender, Emirates Team New Zealand, said canting keels underwent much higher stress levels than fixed keels.
Such keels go through what is known in the industry as ‘cycles’, ie the number of times it bends. Remarkably these cycles are notched up every time the boat tacks, gybes or even goes over a wave!
Some experts say such keels should be replaced every 30,000 miles because of the number of cycles the boat will have accrued in that time, Hayter reports.
The article concludes Ran Tan II’s keel failed not because of strength, but fatigue.
