The 46 ft 9in Watson-class lifeboat was a non-self-righting displacement hull lifeboat, built between 1947 and 1956, and operated by the Royal National Lifeboat Institution (RNLI) between 1947 and 1989.
Description 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 an aft cockpit, turtle shaped shelters, and funnel exhausts. The first boat, William Gammon – Manchester and District XXX, was placed on service at in 1947.
From 1948, the design was completely revised. A new aluminium structure provided a midships steering position in an open cockpit. There was a large aft survivor cabin, which also housed the radio. At the rear of this cabin was a small aft cockpit, with a hatch for access for stretchers, and an emergency helm position. A smaller forward cabin gave access to the engine room and contained the engine controls.
The boats were powered by the same twin 40-bhp Ferry VE4 4-cylinder diesel installation as the earlier boats, but the exhaust was taken up the foremast to outlets well above the deck.
The last boat on service was the Greater London II (Civil Service No.30) (ON 921), built in 1955, and withdrawn from in 1989.
Modifications The 46 ft 9in Watsons had long lives and were updated through their careers. The first major modification was the enclosing of the cockpit, done to all boats from 1960 onwards. The wheelhouse fitted resembled that of the 47ft Watson but there was no room to install sliding doors, weather shields being installed instead.
Radar was installed on most boats, fitted on the wheelhouse roof, with the original aerial rigging and the aft mast removed and replaced by pole aerials. Most, but not all, boats were re-engined, with various examples of the Ford-based 6-cylinder diesel engine as described below.
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.
Engines The 46 ft 9in Watsons were the final boats to be equipped with RNLI designed engines, in this case, the twin 40-bhp Ferry VE4 4-cylinder diesel engines. The lifeboat, introduced in 1954 was the first type to use commercially available engines, followed by the in 1955 and the 52-foot Mk.II in 1957. These all used the Gardner LW engine, in four, five and six cylinder forms respectively.
The Gardner engines were too large and heavy for the earlier types and were only ever used in new build boats. However, in the mid 1950s Ford had introduced new 4- and 6-cylinder diesel engines for their Thames light truck and coach chassis. These soon attracted the attention of marine engine companies and many marinized versions were on the market. In 1961 the RNLI re-engined a , Canadian Pacific (ON 803), with the 4-cylinder Ford-based Parsons Marlin, and in 1963 a programme began to re-engine the and other boats with the Parsons Porbeagle. This 4-cylinder engine was adopted for the 37 ft Oakley-class from 1964 onwards.
The 6-cylinder version was small and light enough to replace the 4-cylinder Ferry VE4 engines, and after the trial installation, again in Canadian Pacific (ON 803) in 1963, a programme to re-engine some s began in 1965. This was extended to the 46 ft 9in Watsons and in 1965 two boats, Tynesider (ON 852) and ''Duchess of Kent (ON 908), were re-engined with these 6-cylinder Ford-based Parsons Barracuda diesels. Rated at 65-bhp, these gave a 62½% power increase, making the boats more powerful than the newer 47 ft Watsons, and between 1965 and 1968, seven boats were re-engined with Barracudas.
In 1969/70, four boats received another 6-cylinder Ford based unit, the Watermota Sea Lion, rated at 70-bhp. From 1971, seven boats were equipped with 70-bhp Ford Thorneycroft 380s, the last as late as 1982, while in 1972 three boats received 70-bhp Ford Mermaid 595s. A feature of the re-engine programme, was the replacement of the foremast exhaust system, by outlets on each side of the hull, similar to the 37 ft Oakleys. This allowed a slimmer, lighter foremast to be fitted. The exhaust system on some boats like the Howard Marryat remained unchanged.
Fleet Aft cockpit type ON Name Built Stations Shelter Radar Comments849William Gammon – Manchester and District XXX1947 1947–1974 19681973Gift of the Manchester and Salford LB fund, built by Groves and Guttridge of Cowes, with internal rudder, costing £16,962. Twin 65-hp Parsons Barracuda Ford 590E 6-cyl. diesel engines, 1968. Sold February 1984.In storage for Swansea Museum, December 2025. 1974–1982 Relief fleet852Tynesider1947 1947–1979 19651980Gift of the Tyneside Blitzed LB fund, built by J. Samuel White of Cowes, with internal rudder, cockpit, costing £16,367. Twin 65-hp Parsons Barracuda Ford 590E 6-cyl. diesel engines, 1965. Sold February 1984.Unaltered, under restoration at Iron Wharf, Faversham, December 2025. 1979–1983 Relief fleet853Winston Churchill1947 1948–1979 19671975Gift of the Civil Service LB fund, built by J. Samuel White of Cowes, with internal rudder, costing £16,535. Twin 65-hp Parsons Barracuda Ford 590E 6-cyl. diesel engines, 1967. Sold July 1983.Renamed Watson Explorer. Stored for restoration at Titchmarsh Marina, Walton-on-the-Naze, August 2025. 1979–1982 Relief fleet 854 Sarah Tilson 1949 1950–1978 No NoLegacy of Mr Tilson, built by Alexander Robertson & Sons of Sandbank, Argyll, with internal rudder, costing £17,790. Sold December 1979.Renamed The Sarah. Unaltered as The Sarah Tilson at Medway Bridge, Rochester, Kent, October 2025. 1978–1979 Relief fleet 855 W. M. Tilson 1949 1950–1969 No No Legacy of Mr Tilson, built by Alexander Robertson & Sons of Sandbank, Argyll, with internal rudder, costing £18,057. Sold August 1970.Last reported as semi-derelict at Magerascouse Road, Comber, County Down, October 2012, now believed broken up.
Midship steering cabin type