The Humphreys designed IOR Maxi Rothmans
Rothmans rounding the Fastnet Rock
The Humphreys designed IOR Maxi Rothmans
Wind tunnel testing Rothmans' L Keel

While Rothmans was still under construction Rob Humphreys embarked on an intensive appendage-testing program, using a high-speed wind tunnel at Farnborough. A series of half-scale keel models were built to get as close to real life Reynolds Numbers as possible and one of these models was an unusual filleted bulb form, developed with technical input from Obara and Van Dam of the United States.

This configuration tested really well and Humphreys had no compunction in committing the yacht’s keel to this concept. It is believed to be the first such keel to have been built, yet now the basic form is almost universally adopted by other designers.

Humphreys has developed the form subsequently and has employed the basic concept on a considerable number of racing and cruising yachts, including the new Oyster fleet.