Derek Kelsall

Derek Kelsall (15 May 1933 – 11 December 2022) was an English multihull sailboat designer latterly resident in New Zealand. He began his career in surveying and in the oil industry. Born in north Wales on 15 May 1933, he died in Thames, New Zealand on 11 December 2022, at the age of 89.

Toria Toria was a trimaran sailboat designed by Kelsall and launched in 1966. It was named after Kelsall's daughter. In 1966 Toria won the first RWYC Two-Handed Round Britain Race.

Trifle Toria led directly to the design of Trifle, a trimaran sailboat designed by Kelsall and produced in 1966 as a further development of his first trimaran. Its load waterline length was .