Multihull World magazine - Issue #57 - August 2002

Sun Yachts and Imp Catamarans assist in Multihull Research

By Colin Ayres

While a great deal of recent research has been undertaken on large catamaran ferries, little study has been carried out on sailing multihulls, particularly in the region of motion prediction and slamming effects. Work in this area will not only assist in the design of faster racing multihulls, but safer cruising boats. To this effect a new Imp 55 was made available to Curtin University for sea trials.

Kristoffer Grande is a Norwegian Masters student at Curtin University, whose thesis is on the study of "Slamming Effects of Waves on Catamarans". He is also attached to the Centre for Marine Science and Technology.

Kristoffer is a keen sailor who has a special interest in large racing multihulls.

Sensors were mounted inside the catamaran to monitor the 3 axes of motion, and an external slam recorder was located forward. Due to the high bridgedeck clearance of the Imp 55, an artificial level was taken 400 mm above the water line.

A logger was deployed in the test area, to monitor wave height with time. The depth of the water was 22 metres, and the sea was typically 0.8m on a 1.5m swell. The wind ranged from 8 to 18 knots.
Various points of sail were undertaken, including powering straight into the wave action. After 3 hours of trials, enough data was stored to keep Kristoffer busy for a few weeks. The loggers were retrieve and the vessel headed for Fremantle Sailing Club.

Sun Yachts wishes to thanks Mr. and Mrs. Marcombe for the use of "Spellbound" during the trials. It is hoped that as more information is gathered on these sailing vessels, a better appreciation may be made of the various positive attributes of well designed and built multihulls.