WHEN diesel engines were first fitted into a life-boat in 1932 a new policy was adopted which was to be of the greatest importance in the history of life-boat construction. Just how im- portant this development has been isshown by the fact that every life-boat being built today is fitted with diesel engines.

The problem of finding the ideal method of providing a life-boat with mechanical power has occupied theminds of designers and engineers for more than a century. For many years experiments were made with steam.

At the Great Exhibition of 1851 a model of a steam life-boat, which was entered in the competition for the Duke of Northumberland's prize, was shown.

Steam life-boats had only a limited success, for many of the difficulties which they inevitably presented were found to be almost insurmountable.

Writing in 1874, Richard Lewis, who was then Secretary of the Institution, pointed out very rightly that the violent motion of a life-boat would often prevent air from being drawn in for the fires; that as a result engines would be disabled; and that there would always be difficulty in finding men with sufficient skill to work these engines among the fishermen and long- shoremen who formed the bulk of the crews.

First Steam Life-boat In 1886 the Committee of Manage- ment appointed a special Committee to inquire into the practicability of using steam power in life-boats. The first order was placed in 1887 for a steam life-boat, although the method of propulsion was that of hydraulic ejection, in itself a forerunner of the Hotchkiss principle later used by the Institution. By 1912 only four steam life-boats and a tug had been built.

It was in 1904 that an internal combustion engine was first installed in a life-boat. The experiment was not an immediate success, and it was not until 1910 that a boat fitted with a Blake motor made a passage of 538 miles in 11 days without any serious mechanical trouble. In the same year another boat fitted with a Tylor engine made a passage of 425 miles in 4 days without mechanical trouble, and from then onwards it became increasingly clear that the internal combustion engine provided the ideal method of driving a life-boat.

Risk of Fire Reduced During the last half-century there have been many developments in the design of life-boat engines, but none has been more important than that of the use of diesel fuel.

The petrol engine, although initially cheaper to make than the diesel engine, has a much higher fuel con- sumption for the useful work obtained.

It had been found that buses fitted with diesel engines were able to travel twice as far as those fitted with petrol engines, with the same fuel consump- tion. Diesel fuel was also cheaper, and because it is less volatile and inflam- mable the risk of fire was greatly reduced. In short, apart from the higher cost of the engines in the first instance, it was clear that the diesel engine would be in every way more suitable.

The first life-boat with a diesel engine was the Yarmouth boat, into which a single 6-cylinder cell-type engine of the Perry Engine Company's design was fitted in 1932. This boat gave good service both at Yarmouth and while she was in reserve. The fitting of this engine gave an oppor- tunity of comparing two boats built at approximately the same time, the Yarmouth boat and the Portpatrick boat, which was fitted with CE4 petrol engines of equal horse-power. The Yarmouth boat could continue at full speed for 118 miles using 29|- pints of fuel per hour. The Portpatrick boat could continue at full speed for only 57 miles with a fuel consumption of 64| pints per hour. At a cruising speed of 7| knots the difference in petrol consumption, and therefore radius of action, was even greater.

Twin Diesel Engines The single 6-cylinder cell-type diesel engine was followed by the develop- ment of twin 4-cylinder diesel engines, and the Institution has up to now placed orders for as many as 134 of these engines.

The earlier diesel engines were fitted into the larger life-boats, but it was clearly desirable that the smallest classes, the 35-feet Liverpool and self- righting types, should also be driven by diesel engines. Boats of these classes often have to be manoeuvred on a carriage and launched over shingle or sandy beaches, and the weight of the engine installation is clearly a matter of great importance.

A dozen years or more ago diesel marine engines in common use for commercial purposes were mostly of some 40 horse-power and weighing approximately a ton. The only really suitable diesel engine which could be developed for use in the smallest classes of life-boats was the FKR3 made by the Ferry Engine Company.

Weighing less than half a ton and developing 21 horse-power at 1,600 re- volutions per minute, the engine used in these small life-boats was a super- charged two-stroke high-speed engine with three cylinders, and a modified version of the four-cylinder unit de- veloped for the Admiralty and used in great numbers in 16-feet fast-planing dinghies. The engine used by the Admiralty was in itself a smaller and modified version of the General Motors GM6 engines.

Kadenacy Principle The life-boat engine worked on the principle developed by the Frenchman, Kadenacy, whereby a higher com- pression and higher power are obtain- ed. The essence of this principle is that if gases under reasonable pressure, having done most of their useful work, are suddenly released or exhausted there will follow a slight vacuum in the space previously occupied by the gases. If the inlet ports are made to open when the vacuum is created, the incoming air will rush in at increased speed, and if the ports remain open long enough a natural supercharging effect will result.

The first of the FKR3 engines was fitted in the Rhvl life-boat in 1949.

It has given good service ever since and there are now 24 life-boats fitted with these engines.

Commercial Engines Late in 1950 the Committee of Management gave close consideration to the possibility of fitting commercial engines into life-boats. The problems of cost, simplicity of maintenance and ready availability of spares influenced the decision which was eventually taken. It had also become clear that it was extremely difficult to maintain engines in a completely watertight state, and that certain, items such as ball-races and magnetos of the older petrol engines were tending to deter- iorate rapidly. It was apparent too that there would be advantages in adopting an engine in daily use in the commercial world which had survived the tests of competition.

Experiments Continue In 1954 a new type of life-boat fitted with two 4LW Gardner diesel engines was sent to Coverack. A full descrip- tion of this boat appeared in the September, 1954 number of the Life- boat. A boat of a similar type was later sent to Troon.

As in all matters connected with the construction and design of life-boats experiments continue, but there is now no room for doubt that the policy of fitting diesel engines has been an unqualified success..