Kelsall Catamarans design company was established in Cornwall, United Kingdom in 1965. Operated boat building company alongside the design company for 20 years, producing a wide range of craft, all based on the use of PVC foam and the expertise in using it. Three projects by this company were the largest of type at the time. Kelsall CatamaransThe company has operated continuously since, moving to New Zealand in 1998.

As designer, as builder, as sailor and as one of the most innovative of the very small band of men who can claim to have played an important pioneering roll in the development of the modern multihull, Derek Kelsall offers experience and style along with very effective and original ideas. The most effective build methods, which are just as applicable for the professional as the first time builder, are combined with a wide range of designs to fill the requirements of almost anyone wishing to take to the water in catamarans.
Derek took part in the single handed trans Atlantic Race in 1964 and won the first Round Britain Race on his own first design in 1966. This multihull was the first to win a major offshore race and the first yacht built of foam and fiberglass. The pioneering work with these materials lead to major design and build contracts for racing yachts, included winners of the Solo Atlantic Race and the first Whitbread Around the World race.