When in the mid-1960s the RNLI decided to have six fast steel lifeboats to a 44-foot design developed by the United States Coast Guard, the Lowestoft shipyard was chosen to build them—and two of the six went to East Anglian stations, the KhamHo Great Yarmouth and Gorleston and the Margaret Graham to Harwich. Since their introduction in 1967, the Gorleston and Harwich boats have respectively launched 102 and 79 times for 42 and 30 lives.BRITAIN'S lifeboat fleet is at present being re-equipped with new and faster boats, and the Lowestoft, Suffolk, firm of Brooke Marine Ltd. is playing an important part in the RNLI's development programme.

On May 4 the first of the new 50-foot Thames class lifeboats, now being built at the yards of Brooke Marine, was shown to the Press during routine capsizing trials. A series of photographs depicting the tests appear overleaf.

The design of the Thames class lifeboat resulted from a decision by the Committee of Management of the RNLI that there was a requirement for a lifeboat similar to but larger and faster than the 44-foot Waveney class.

The basic hull requirements were as follows: Length overall to be about 48 feet 6 inches; a speed of about 18 knots; to be a self-righter; radius of action of about 100 nautical miles; draught not to exceed 4 feet 9 inches; acrew of five; the machinery installation, equipment and navigational aids to conform to the Institution's normal standards.

The design was undertaken by the Institution's staff and was model tested by the British Hovercraft Corporation, of East Cowes, to confirm the performance characteristics.

Brooke Marine, of Lowestoft, were then given the task of developing a design study in detail. Various options were explored and after further tank tests some detail changes were made.

An order for two vessels was placed with Brooke Marine and the first was demonstrated on May 4.

The hull plating of this prototype (50-001) is of 3/16-inch Corten steel on longitudinal hull plate framing. A double bottom from the forepeak to the after end of the engine room is a feature of the design. The lining of the forward accommodation is of plywood panels covered with vinyl sheeting and the deck is of aluminium covered with non-slip paint.

Watertight transverse bulkheads subdivide the hull into: forepeak and cable locker, forward and amidships cabins,engine room, after cabin and tiller flat.

The watertight welded aluminium wheelhouse contains all instruments, controls and electronic equipment, and the boat can be navigated from this position without any member of the crew being required in any other part of the vessel.

The vessel depends upon the watertight integrity of the superstructure for her self-righting capability. The amidships cabin contains all the radio equipment and has a bench seat and table on the port side. The forward cabin is fitted with locker seats and the after cabin, as well as being fitted with locker seats, also includes a curtained-off lavatory.

To meet the manoeveurability requirements twin spade rudders are fitted. The twin main engines are General Motors 8V-71, each developing 390 shp at 2,300 rpm fitted with Allison hydraulically operated reverse reduction gearboxes giving a reduction of 2.00 : 1.00. The gearboxes are handed to give outboard turning propellers.

The engines are fitted with single lever engine controls operated from the wheelhouse.

The auxiliary is a Fetter PJ2W dieselwhich drives both an AC90 generator and a fire and salvage pump.

The main and auxiliary engines are arranged with electric starting facilities and a 24V DC supply from each of two separate 260 amp. hour capacity batteries.

Each main engine is fitted with a 90 amp alternator with built in diode rectification. Control equipment is transistorised. The auxiliary set is also fitted with a 90 amp alternator and by means of a Constavolt unit provides a 24V DC supply for battery charging.

Electrical services include: lighting throughout the vessel, instrumentation, circuit protection and warning systems, ventilation fans, heaters for all working spaces, glow plugs on the main engines for use in cold weather, a windlass and windscreen wipers.

Electronic equipment comprises: Kelvin Hughes type 17 W Radar, Dccca Navigation Mk. 21, Kelvin Hughes Falkland MF radio telephone, Pye Westminster VHP radio transmitter and receiver, Ferrograph echo sounder, and Easco Intercom five station unit.The prototype's other technical details are: Length overall 50 feet Breadth moulded 14 feet 6 inches Depth moulded 5 feet 5 inches Fuel capacity 400 gallons Drinking water 10 gallons Load displacement 23.5 tons Load draft aft 4 feet 6 inches Load draft for'd 2 feet Maximum speed 19 knots Range at full speed 198 nautical miles Cruising speed 17 knots Range at cruising speed 229 nautical miles..