Designer clarifies cause of keel failure
Published on January 9th, 2020
Following the 628nm Rolex Sydney Hobart Yacht Race, when storms buffeted yachts being delivered home along the eastern Australian coast, the Ker 40 Showtime got the worst of it when its keel broke off and capsized.
While the seven crew on board were able to activate the liferaft and be safely rescued, the question lingers why the boat broke. In this report, Jason Ker of Ker Yacht Design offers some clarity to the question.
I’d like to make clear that the keel lost by the Ker 40 Showtime was not designed by Ker Yacht Design. The yacht had a retrofit keel fitted, designed by its owner’s local design office near Sydney and built by a local fabricator.
We have designed a great many keels over the last 23 years which have been constructed by many different builders around the world, and none have ever failed. To the best of our knowledge, Showtime is the only yacht designed by us to have had a keel fitted that was not designed by us.
Showtime’s keel was configured as a vertical hollow strut welded to a horizontal mounting plate, which in turn was sitting in a shallow recess in the boat’s hull and bolted to the boat’s structure. This is not a design approach we would ever endorse as the high stress point at the junction is coincident with the horizontal welded joint.
The skipper of the delivery voyage Rob Buchanan and his crew only survived through extremely calm thinking and bravery under stressful circumstances. Rob woke hearing a metallic ‘ping’ just before he was thrown across the boat from his windward bunk as they capsized.
While they made their plans to escape, it was apparent to Rob that the inverted boat was holding air pressure in the hull, so the top plate of the keel can only have remained fully bolted to the yacht. When the crew swam down out of the boat, they saw that the vertical part of the keel was missing, revealing that the keel had failed at the welded joint between the exposed vertical and the recessed horizontal parts.
Ker Design would support any World Sailing move to ban this low cost but high risk style of ‘welded T’ keel construction.
The 2019 fleet for the 628nm Rolex Sydney Hobart Yacht Race saw 157 starters for the 75th edition on December 26. From Sydney Harbour, the fleet sailed out into the Tasman Sea, down the south-east coast of mainland Australia, across Bass Strait (which divides the mainland from the island State of Tasmania), then down the east coast of Tasmania. At Tasman Island the fleet turned right into Storm Bay for the final sail up the Derwent River to the historic port city of Hobart.
Attrition list in 2019:
· Faster Forward, Sydney 38 – Steering problems
· Hollywood Boulevard, Farr 55 – Broken rudder
· Minerva, DK 43 – Reason not listed