SINCE the first experiments with motor life-boats in 1904, the Institution has used petrol engines. Diesel engines, although they have important advan- tages have, until recently, not been possible, because, with their low speed of revolution, they have been too heavy for life-boats. In recent years, how- ever, the speed of the revolutions in the Diesel has been greatly increased, and, as a result, the weight has been reduced to little more than the weight of the petrol engine of the same horse- power.

In 1934 a six-cylinder 85-h.p. Diesel engine was installed in a reserve motor life-boat, and during the greater part of the year experiments were carried out with this life-boat at various stations. She then became the Yarmouth, Isle of Wight, life-boat. As a result of the success of this life-boat it was decided to order a pair of 40-h.p.

Diesels to instal in a new motor life- boat, and this life-boat was stationed at Yarmouth, Isle of Wight, last summer, the previous Diesel-engined life-boat returning to the reserve fleet.

Of the ten motor life-boats under construction at the end of last year six will have Diesels, and of eight more laid down in February this year five will have Diesels. These life-boats are all of the 46-feet Watson cabin type. The Diesel engine would be too heavy for any of the lighter types of life-boat These Diesel engines are 40-h.p.

four-cylinder engines, running at 1,200 revolutions to the minute, the same number of revolutions as the 40-h.p.

four-cylinder petrol engines. They weigh 20 cwts. as against the 19 cwts.

of the petrol engine. The life-boats develop the same speed, approximately 8j knots, whether fitted with petrol or Diesel engines. The Diesel has two great advantages for life-boat work.

It uses heavy oil, which is much less inflammable than petrol, so that the risk of fire is much smaller. It is much more economical of fuel, so that, carrying the same amount of fuel, a life-boat with Diesel engines can travel nearly twice as far as the same life- boat with petrol engines. With petrol engines the 46-feet Watson cabin life- boats can travel 116 miles at full speed.

With Diesel they can travel from 210 to 230 miles..