Photo: Brett Costello

Swiss army knife supermaxi

Bob Oatley's supermaxi receives a Dynamic Stability Systems foil

Wednesday August 14th 2013, Author: Rob Mundle, Location: Australia

Bob Oatley’s supermaxi Wild Oats XI has been retrofitted with a Dynamic Stability System retractible foil aimed at improving her performance downwind.

The foil will be put to the test for the first time under racing conditions at Audi Hamilton Island Race Week, starting on 17 August.

Wild Oats XI, the six-time winner of line honours in the Rolex Sydney Hobart race, will be subjected to an extensive analysis program when using the wing during the week. It will be an important part of her preparation for this year’s Hobart classic.

Dynamic Stability Systems is a collaboration partner in the project and will benefit from an exchange of data with the Wild Oats XI team.

The foil concept for Wild Oats XI evolved after months of research into finding a way to improve the yacht’s ability to surf when sailing downwind in strong winds.

"We considered many options while looking for a solution to the problem," said Wild Oats XI’s co-owner, Bob Oatley’s son, Sandy. "After weeks of deliberation the hydrofoil wing became the logical answer."

This has led to the fitting of the DSS system, a retractable foils that is mounted in a horizontal cassette that extends laterally across the yacht at the waterline, between the mast and keel. The DSS foil on Wild Oats XI is operated using hydraulic motors.

"The purpose of the wing is to provide hydrofoil-type lift to the forward sections of the yacht so drag is reduced and speed increased," Sandy Oatley said. "Its intended use is only for downwind sailing. On upwind legs it will be fully retracted and not project beyond the hull."

It was while Wild Oats XI was sailing downwind across Bass Strait in last year’s Rolex Sydney Hobart race – while heading to her record-breaking line honours victory – that it became apparent there was an opportunity for improvement. Senior members of the crew agreed that if a way could be found to increase lift in her forward sections then her average speed – which was at the time in excess of 20 knots – could only go higher.

The new carbon fibre foil was made in New Zealand and is 55cm wide, and when in use will extend 2.75m out from the hull on the leeward side.

It was tested for the first time during trials off Sydney a week ago, and the consensus was that it improved the yacht’s performance.

"There was a noticeable lift in the bow when we were reaching and running," said Wild Oats XI’s skipper, Mark Richards. "At this early stage it’s safe to say it makes a difference. We are certainly looking forward to putting the concept through a complete series of tests at Audi Hamilton Island Race Week."

The fitting of the wing is the latest in a string of modifications aimed at keeping the eight-year-old Wild Oats XI competitive against more recent designs. This recent change has led to Richards and his crew affectionately referring to the yacht as ‘the Swiss Army Knife’, because of the number of appendages she now boasts: the new hydrofoil wing, a retractable forward rudder, two retractable daggerboards, the canting keel, and the conventional rudder at the stern.


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