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Saturday, October 21, 2017

Incat Crowther Powers Waterski Record

April 14, 2010

Photo courtesy Mark Seaton Photographics

Photo courtesy Mark Seaton Photographics

Incat Crowther supported the Horsehead Water Ski Club as it recently set a new water ski world record on the 28th of March 2010. The club had already set the mark of pulling 120 skiers from a deep start in January this year (the most ever pulled behind one boat), but with only 99 making it through the required nautical mile it was two skiers short of setting a new record. For the successful attempt in March, the club managed to get 116 skiers started and still had 114 up at the conclusion of the nautical mile, smashing the 100 skier mark set in 1986.

The record was set behind Eagle, an Incat Crowther designed 118 ft catamaran tour vessel that operates in Strahan, Tasmania. The powerful yet efficient vessel was fitted with a custom fabricated boom across its stern to spread the large number of skiers out. Incat Crowther provided structural design support for the boom and provided detail drawings for the manufacturing of all components and attachment points.

Incat Crowther Naval Architect Kristian Fet spearheaded the support effort of the Sydney-based design office. “The club came to us with technical questions, and we welcomed the opportunity to get involved in a world record,” he said. “As well as designing a boom that would be strong enough, we had to come up with a way of attaching the boom that minimized the need for any modifications to the vessel.” The club had previously attempted to set the record using Eagle but was restricted to using boom designs not rigidly attached to the then brand new boat. This raised a number of issues and all the three previous attempts on breaking the record were halted by boom or rope failures.

Following these first unsuccessful attempts, the committee finally obtained permission from the operators of Eagle to attach a more substantial boom to the vessel. The organizers then turned to Incat Crowther for design help. Fet was handed a conceptual design and through extensive finite element analysis was able to simplify the original concept into a boom that was both easy to construct and that can be assembled in a short amount of time. A nonlinear static solver in combination with cable elements for the support ropes enabled an accurate prediction of the boom’s behavior as it is gradually loaded up with the drag from 120+ skiers. “The use of stepped load increments allowed us to view the transition between only gravity acting on the boom setup and the full design loads applied. Having satisfied ourselves that all forces and stresses observed had comfortable safety factors on failure attention was then turned to the finer details of attaching the boom system to the boat.”

The attachment is so simple that the ski team was able to do the record run at 7.30am and remove the boom setup in time for the ferry’s regular tourist run at 9am! Disassembled, the complete boom and mast fits comfortably on the back of a small truck.

The Horsehead club’s achievement continues a long association between Incat Crowther and the world record. The record of 100 skiers, which stood for nearly 24 years, was set by the Cairns and District Powerboat and Ski Club, using an Incat Crowther designed vessel. Prior to the 100-skier record being set, an attempt was made in San Francisco Bay using an Incat Crowther vessel. In 2000, Incat Crowther affiliated yard Nichols Brothers, made an attempt using the 40m Klondike Express.

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