UNTIL 1921 all the Institution's motor life-boats were of a weight which made it necessary that they should either lie afloat or be launched down a slip-way.

In that year, the first boat was sta- tioned at Eastbourne of a new type, which was sufficiently light to be launched off a carriage or the open beach. This boat was experimental.

She was followed by another, an im- provement on the first boat also experimental, which was stationed at Scarborough in 1923.

The difficulty in designing this new type was to get her sufficiently light for launching and at the same time to keep her construction sufficiently strong.

The first experimental boat was just under 7 tons, with crew and gear on board. The second was over a ton lighter, 5 tons 17 cwt., but after experience with her it was found necessary to strengthen her framework.

Then in 1929 a third boat was built, with important modifications. This boat was stationed at Hythe, Kent, and with her the experiments had reached a suc- cessful conclusion. There have been minor modifications since, but theHythe boat is the standard to which the Insti- tution has since built this light type.

Her weight, with crew and gear on board, is 6 tons 14 cwt. The first experimental boat was 35 feet by 8 feet 6 inches. This was increased to 35 feet 6 inches by 8 feet 10 inches. In the latest boats of the type it has been found possible to increase the beam to 9 feet 3 inches, thus adding con- siderably to the stability of the boat, although without diminishing her self- righting power, and in future boats of the type the beam will be still further increased to 9 feet 6 inches.

This type is built with a double skin of mahogany, keel of teak, ribs of Canadian rock-elm, stem and stern posts of English oak, and air-cases of Columbian red cedar, which is now being used instead of white deal as being a lighter wood. She is divided into six watertight compartments and is fitted with 110 air-cases. She has twenty-four relieving scuppers and these can free her entirely of water in 20 seconds. If she is bottom up she can right herself in 4J seconds.

The first boats of the type were fitted with 35 h.p. engines built for racing cars, but these were not found very satisfactory, and as a result of this experience with them the Institution has designed its own engine. It is a 6-cylinder high-speed engine running at 3,300 revolutions a minute, as com- pared with 1,200 revolutions a minute in the 60 h.p. and 40 h.p. engines used in the larger types of life-boat. It develops 35 h.p. with a combined self-contained reduction gear, giving a propeller speed of 900 revolutions a minute. The engine is water-tight, and would continue running even when entirely submerged, for the air-intakes are well above the water-line even when the boat herself is water-logged.

The maximum speed is 7£ knots, and, as with all the Institution's motor life-boats, there is a great reserve of power, so that the maximum speed can be maintained even in very severe weather. The boat carries 48 gallons of petrol, and the engine's consumption is just under 3J gallons an hour at full speed, so that she can travel 106 miles at full speed without refuelling.

The boat is fitted with a drop keel, and carries a fore lug and jib which can be used either with the engine running or as auxiliary power in the event of any failure of the engine.

She carries a crew of from seven to ten men and in rough weather can take thirty people on board.

Since the Hythe boat of this type was completed in 1929 more life-boats have been built of this type than of any other, and it has made it possible to replace pulling and sailing life-boats with motor life-boats at a large number of stations where, owing to the launch- ing conditions, it was impossible to place motor life-boats of the heavier types.

There are now ten of this type on the English coast, four on the Scottish, three on the Irish and one on the Welsh coast..