Designed by RNLI naval architect James Rennie Barnett, the boats pioneered many features which were to become standard on future lifeboats.

They were, however too large to be slipway launched and had to be moored afloat at a time when the RNLI preferred to keep lifeboats in boathouses and consequently, only four were built.

The class was powered by two 60 bhp Weyburn CE6 6-cylinder petrol engines with a single exhaust funnel ahead of the aft shelter.

However, it was overtaken by events as James Barnett turned to midships cockpits and the new boats emerged as the 52 ft [15.8 m] class the following year.

In 1976, ON 860 also received Barracudas while serving in the relief fleet and this boat was the final member of the class in service when retired in 1981.