THERE is one very important difference between the designing of a Life-boat and the designing of her engine.

The requirements of the Institution, so far as hulls are concerned, are quite special. No other small craft are built which would be in any way suitable for the Life-boat Service. In the case of the engine, however, this is not the case.

Any engine that was designed entirely to comply with marine conditions as met with in small open boats would be in every way suitable for the Life-boat Service, provided such engine were manufactured in accordance with the usual practice appertaining to auto- mobile engines.

This being so, it is very unfortunate that there does not exist, in the opinion of the technical officers of the Institu- tion, any standardised engine on the market which really meets the require- ments of small open boats and is, there- fore, suitable for Life-boat work. The ] result is that when, some time ago, our growing experience of Motor Life-boat work made it seem advisable to have a new engine embodying that experience, it was considered best for the Institution to design one for itself.

A design was made, and specifications were drawn out, at the beginning of 1920, and Messrs. J. Tylor & Sons, Ltd., who had made practically all the previous Life-boat engines, were instructed to build the engine. Unfortunately, before very much progress had been made, they had to discontinue all work of this kind, and there was nothing for the Institution to do but to take over and complete the work itself.

The engine has been constructed on what is termed " the Component system," that is to say, detailed draw- ings of the various parts have been issued to different firms who make a speciality of them, and contracts placed for their supply. When completed, theywere delivered to a convenient engineer- ing works near Godalming, the Weyburn Engineering Co., Ltd., to which was entrusted the work of erecting and testing the engine.

The testing of the engine was rather an anxious business. In the first example of an entirely new design one might expect to experience some trouble. We were very fortunate in finding nothing more serious than some faults in the starting motor, which was bought from an outside firm practically complete, some faulty piston rings, and car- burettors which required rather a long time for adjustment. Eventually the engine went through the whole of its tests in a very satisfactory manner.

Unfortunately, while the engine was receiving its final coat of enamel in April last, before being sent to Cowes to be installed in a Life-boat for its test at sea, part of the Weyburn Works were burnt down, and the engine was so seriously damaged that it will be at least three months before it is in working order again.

The features which we considered essential, and which were embodied in the design, are as follows :— The engine is spray-proof, all working parts, ignition details, and other items which can be effected by damp, rust or dirt, being enclosed in a water-tight cover, and if there are any actual moving parts, they are supplied with a copious bath of lubricant, the lubricant being pumped up from the bottom of the crank chamber by a very powerful pump, and, after being filtered and cooled, distri- buted throughout the whole of the engine.

As a matter of fact the only moving part that can be seen or touched is the flange on the thrust shaft at the after end of the engine, and this passes into the reverse gear through a substantial gland. For this reason the engine is submersible, the limit of submersibility being the air intake to the carburettor.

If for demonstration purposes a hose were attached to the air intake, the engine could be lowered as many feet under water as the length of the intake and the hose, and still continue to run.

It is dangerous to have hot pipes or parts on a marine engine, besides being uncomfortable and unsatisfactory, and, therefore, every hot part is enclosed in a water jacket.

Many engines, in themselves excellent, are made without a reverse gear, and this gear, probably made by another firm, has to be installed in the Boat in such a manner that it is absolutely in line with the engine, although there is no guarantee that the movements of the Boat will not place it out of line.

A marine engine ought to have its reverse gear as an integral part of the engine both to avoid this serious diffi- culty, and also the necessity of providing a separate oiling system. That is what we have done.

The thrust block is a very vulnerable point in the usual marine engine, and this block also should be part of the one system, so that it can share in the adequate oiling arrangements provided for the engine. This is necessary, not because a ball-thrust requires much oil, but because, in a marine engine, if there is a flow of oil, any water which may in- advertently find its way into such a delicate thing as the ball-thrust, will at once be washed away and removed to the filter.

In a marine engine, and especially in a Life-boat engine, the control should be as obvious and as easy to operate as are the controls in a motor car, and for this reason inter-connection has been arranged between the throttle and control gear so as to leave one operation only for the driver to attend to. This involves a certain amount of mechanical work which may appear to have com- plicated the engine, but it has simplified the handling of it.

It will be realised that there must be one definite temperature at which an engine gives the best results, and also that, unless the temperature is regulated, it will vary greatly between the extremes of the engine running slowly in neutral in the winter, and fully opened out on a hot summer's day. To rely upon hand regulation to rectify this has been found to be unsatisfactory, and a very simple apparatus has been added to this engine which automatically keeps the water in the jackets at the same tem- perature by regulating the amount which it allows to pass through.

Great trouble has been experienced in the past in starting some of our larger engines on a cold morning. The new engine, therefore, has been fitted with a starting gear which is not dependent on outside batteries or bottles of compressed air, but which consists of an ordinary bicycle motor.

It must be realised that a Life-boat engine (in fact any marine engine), must not stop, since there are times when a stoppage would mean disaster. To provide against the possibility of stop- ping every reasonable precaution has to be taken, and one of these precautions has been to design the bearings of the crankshaft of such ample proportions that they are not at all likely to give any trouble.

While it is not considered admissible that any adjustment should be made to a Life-boat engine while actually running on service, yet there are times when a quick adjustment for examination is essential, and for this reason every effort has been made to allow parts which require adjustment, examination, or replacement, put in such a position that they are accessible. For instance, the whole of the pistons can be removed from the engine through the crank chamber doors, and this has actually been done in one hour.

In order to provide for a thorough overhaul of the engine at stated intervals without undue expense or trouble as would be occasioned by removing the whole engine from the Boat, the design includes a detachable cylinder head, which contains all the delicate mechanism, such as the valves, ignitors, coils, etc., while all pipe-joints for the exhaust, water and oil circulations are made on the engine body. This allows the head to be removed, the valves ground in, and adjustments made without breaking any joint other than the main cylinder head-joint which is a plain soft copper grummet, as it is called, and the head can be replaced without upsetting the adjustment of the parts.

The engine is capable of giving 100 h.p., but will be running at some- where about 80 h.p., and together with its reverse gear it occupies the same space as the old type 60-h.p.

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