After the final three 46ft Watson-class boats had been completed in 1945/6, production switched to the slightly longer 46 ft 9in type in 1947.

The first five boats were very similar in appearance to the final 46 ft types, with aft cockpits, turtle shaped shelters and funnel exhausts.

At the rear of this cabin was a small aft cockpit with a hatch for stretchers to be passed in and an emergency helm position.

Finally, from the early 1980s all of the midships steering types (except ON 908, lost in the Fraserburgh disaster) were fitted with an air bag on the aft cabin roof to give a once only self-righting capability.

The 6-cylinder version was small and light enough to replace the 4-cylinder Ferry VE4 engines and, after a trial installation in ON 803 in 1963, a programme of re-engining some 46ft Watsons began in 1965.

A feature of all of these re-engining programmes was the replacement of the foremast exhaust system by outlets on each side of the hull, similar to the 37 ft Oakleys.