NEWS Multihull designer dies 03/01/2023 Save article Multihull designer and boat builder, Derek Kelsall, has died aged 89. SHOW FULLSCREEN Derek Kelsall with his wife Clare Derek is credited with creating the modern-day trimaran, introducing French sailing legend Eric Tabarly to multihulls and being one of the first to champion foam sandwich construction. Derek was born in North Wales in 1933, growing up in humble surroundings. He studied engineering at Bristol University but was unable to complete his degree when he ran out of money. After completing National Service in Kenya, he entered the oil exploration business working for BP in Libya. His career took him to Texas, at the time when his passion for boating was growing, along with an interest in multihulls, both sailing and building them in the Caribbean. This culminated in a decision to enter the second edition of the Observer Singlehanded Transatlantic Race (OSTAR) in 1964 racing Folatre, a 35ft plywood Arthur Piver-designed trimaran which Derek managed to prepare for the race in just two months. After the race, Derek’s interest in multihulls led to him attempting his own trimaran design. The 45ft Toria was one of the most influential multihulls ever, establishing the fundamental concept of what a racing trimaran should look like. SHOW FULLSCREEN Derek Kelsall’s trimaran Toria is believed to be the first boat in the UK to be built using foam sandwich construction The craft had twin crossbeams attaching the relatively high volume, fine bowed floats to the centre hull, their geometry such that at rest only two hulls ever touched the water. She is also said to be the first boat to be built in the UK using foam sandwich construction. Her success on the racecourse created great interest in offshore trimarans, including from French sailing legend Eric Tabarly who helped deliver the boat from Cornwall to the 1967 London Boat Show and who afterwards returned to France to work on his first trimaran with French naval architect André Allègre. Derek continued to enjoy further success with his small trimaran designs into the 1980s, including his Toria development Trifle. His greatest series of race boats were the various ‘Three Legs of Mann’ trimarans built and sailed by Isle of Mann-based Nick Keig. His use of foam sandwich construction attracted some of the top campaigns including Sir Thomas Lipson’s 1968 OSTAR victory which led to Derek building the 78ft long Alan Gurney-designed Great Britain II for Chay Blyth followed by two further large trimarans for the legendary sailor. From the mid-1980s for the rest of his career, Derek’s work as a yacht designer mainly focussed upon fast cruising catamarans, accompanied by further developmental steps in boat building techniques. KSS, the Kelsall Swiftsure Sandwich technique, used flat panels that could be laid up rapidly on a table, enabling construction time to be dramatically reduced, a process Derek first used in 1973 and constantly evolved over subsequent decades. He emigrated to New Zealand after the death of his wife Clare, from where he continued to design yachts and motorboats and promote the KSS. Derek is survived by his partner Paula, daughter Victoria Liepins and son Liam and Liam’s two children Elena and Libby. Meanwhile Derek’s designs, including many of his early work from the 1960s, thanks to their foam sandwich construction, have survived him and are still to be found in every corner of the globe. Topics BoatbuilderDerek KelsallIndustry Newstrimaran

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