With the building of a 48 foot 6 inch steel-hulled life-boat the Royal National Life-boat Institution has introduced a new class of boat into the service. A life- boat of this type was shown to the press at Southampton on 17th July, 1969.

She was built at the yard of Messrs. Camper & Nicholson in Southampton and cost about £70,000.

The new life-boat for Rosslare Harbour is the Mark III type. Life-boats of the 48 foot 6 inch class are the largest size of boat being built under the Insti- tution's current building programme, and these boats are equally suitable for slipway launching stations and for stations where the life-boat is permanently afloat. The Mark III life-boat has a steel hull of all-welded construction, a cast-iron ballast keel and aluminium superstructure.

The use of steel for the hull of the Mark III type is a major change from the Mark I and Mark II versions, which had wooden hulls. This change has been brought about largely by the declining numbers of craftsmen boatbuilders available in this country. It also reduces the number of man-hours involved in building the hull.

The hull is sub-divided by watertight longitudinal bulk-heads into centre and wing compartments, and further sub-divided by four main watertight bulkheads, by a watertight double bottom in way of the engine room and a watertight flat in way of the after cabin.

The double bottom compartments in way of the engine room, the fore peak compartment and the void compartments outboard of the longitudinal bulk- heads are all completely filled with rigid polyurethane foam by the in-situ process, to provide reserve buoyancy in the event of hull damage.

EXCELLENT STABILITY Watertight doors are fitted between the wheelhouse and after cabin, the wheel- house and engine room, and the engine room and forward cabin. As the door between the wheelhouse and the aft cabin is one which is frequently used for access by the crew, it was decided to arrange two doors with a cofferdam space between them so that it is possible to keep one or other of the doors shut at any one time, to prevent flooding of the aft cabin in the event of a capsize. Warning lights are fitted in the wheelhouse to show whether any other door or hatch is open.

A watertight hatch is fitted at the aft end of the after cabin. This is large enough to allow a stretcher to be passed into the cabin. A watertight hatch is fitted over the fore cabin for emergency access.

The life-boat has excellent stability properties, having a metacentric height of 3.4 feet and also natural self-righting ability from any angle of capsize.

The machinery installation consists of two Gardner 6LX engines with Gardner2 UC reverse and 2:1 reduction gearboxes. Each engine develops 110 b.h.p. at 1,300 r.p.m. Propellers are 28 inch diameter aluminium bronze and the stern gear consists of oil-lubricated stern tubes, which extend to the shaft brackets, and stainless steel propeller shafts.

All instruments and gauges are mounted on a watertight bulkhead between the wheelhouse and the engine room. Remote controls for the engines are mounted alongside the steering position in the wheelhouse.

The steering gear is of Mathway manual type and the boat has twin spade rudders. The use of twin rudders is a change from the Mark I and II versions which had the more usual single large rudder mounted abaft the stern port.

Trials so far with the Mark III type indicate that a useful improvement in manoeuvrability has been obtained by the use of twin spade rudders.

The life-boat is equipped with the following navigation aids: two compasses, radar, M.F. radio, V.H.F./U.H.F. radio, echo-sounding equipment.

This class of life-boat has a seven-man crew and can carry a maximum of about 100 survivors..