IT is just a year (vide Life-boat Journal, February, 1898) since a description was given in these pages of the steam Life- boat Queen, which was sent to her station at New Brighton in October, 1897. After the launch of that boat and before the steamers required for Grimsby and Pad- stow were ordered, the whole subject of the application of steam to Life-boat work was thoroughly reviewed and discussed by the Committee of Management and the Officers of the ROYAL NATIONAL LIFE-BOAT INSTITUTION with a special bearing on the method of propulsion in use or to be em- ployed in the future, whether taking it all in all the Institution was justified in still adhering to the " turbine," or, in view of the development of the protected screw propeller as used in the Nile and Niger gunboats, this latter method should be adopted. The screw propeller gained the day and the two boats were ordered of Messrs. J. SAMUEL WHITE & Co., Ltd., of East Cowes.

The boats are practically identical, the only difference being that it was found desirable to slightly alter the position of the coal bunkers in the second boat (Padstow) so as to bring the weight a little further aft, and also step the mast abaft the funnels to prevent the lug sail being burned.

On p. 273 will be found sketches of the Life-boats, showing profile, deck plan and midship section, in which the principal dimensions are given, and on p. 274, a reproduction of a photograph of the Grimsby boat, James Stevens No. 3, on her full-speed trial.

Now to compare the two methods of propulsion:—On referring to the Life-boat Journal published on the 1st November, 1890, in which was a description of the first steam Life-boat Duke of North- umberland, the principal reasons for adopting the turbine will be found, and they were practically as follows:— (1) That the position of the " turbine " or "centrifugal pump" in the chamber very nearly in the midship section of the boat would render it much less liable to be damaged from taking the ground, or from wreckage, or to be fouled by ropes, &c., than the screw propeller.

(2) That in & heavy sea owing to its position and design the engines driving it would not" race." (3) That the boat could be manoeuvred entirely without reference to the engine room by means of handles in the cock-pit controlling the water discharges on either side of the boat, and in addition to this, that in case of the steering gear being disabled the boat could be kept under control by this means.

With regard to the first reason given, experience has not entirely borne out the hope that the turbine would have a perfect immunity from damage or fouling, for there have been instances, though only a few, of the inlet passage being fouled by becoming choked with seaweed, and the pump injured by having stones, gravel and sand drawn into it. Also on one occasion one of the steam Life- boats was temporarily disabled by a rope being drawn through the inlet and wound round the spindle of the pump, bringing the engines to a standstill. The "turbine" cannot be cleared without putting the vessel into dock or on a " grid," which is a distinct drawback.

With regard to reason No. 2, the turbine has proved everything that could be desired, and also as regards reason No. 3.

Before drawings and specifications of the new boats were made out these three points were all carefully discussed; and in addition the serious trouble which had been experienced by the corrosion of the inlet and outlet pipes of the Duke of Northumberland and City of Glasgow was considered, and also the extra power required to propel a boat fitted with a turbine as compared with that required to propel a precisely similar boat with a screw. What was thought desirable was to be able to fit a screw in such a position that point 1 would be better carried out 14th January, 1898, and the first one, viz., James Stevens No. 3, for Grimsby, was ready in September last, when a series of exhaustive trials took place in the Solent, the results of which amply justified the Institution in coming to the decision of adopting the screw propeller.

The steam Life-boats Queen and the James Stevens No. 3 are, as the following table shows, almost identical in displace- ment, and as better results have been attained in the Queen than in the other two turbine steam Life-boats Duke of Northumberland and City of Glasgow, it is Particulars. Maximum Full Speed. Ordinary working Full Speed. Queen. James Stevens No. 3. Queen. James Stevens Ao. 3. 55 ft. X 15 ft.

31-87 tons.

2ft. lljins. , 198 143 Ibs.

23-8 ins.

1 • 55 ins.

398-6 8-832 56ft.6ins.X 14ft.

31 -75 tons 3 ft. 5J ins.* 179-927 150 Ibs.

23-65 ins.

1 • 14 ins.

423-2 9-59 ------ 97 ----- 352 8-5 2cwt.lqr.231bs. Load displacement. .

Mean draught .

Mean Indicated H.P. . .

Steam-pressure .... 107-6 Air-pressure in utoke hold Mean revolutions .

Mean speed ....

Consumption of coal per 3C8 8 3cwt. 3qrs.l81bs. * The draught of the James Stevens No. 3 is taken to the bottom of the bilge keels which come 5J ins. below the actual body of the boat.

than with the turbine, and at the same time point 2 would be equally as well attained, while a slight sacrifice of man- oeuvring efficiency, point 3, would be made, but this would probably not be felt in practice.

The result of the discussion was that it was decided to adopt the single screw propeller fitted into a cavity formed in the vessel's structure, under the cockpit, about half way between the after end of the engine room and the stern post (see profile and midship section, p. 273).

The two boats were ordered on the most desirable to compare her with the James Stevens No. 3.

The above table shows the comparative efficiency of the two boats at maximum full speed and at ordinary working full speed. It was found on the trials that the power necessary to drive the Queen at a speed of 8 knots per hour was 168 I.H.P., while the power required to obtain the same result from the James Stevens No. 3 was 97 I.H.P. or 61 horse power less than that of the Queen= 62 -9 per cent, of a saving in favour of the screw propeller. Also it will be seen by reference to above table that the Queen burns 3 cwt. 3 qrs. 18 Ibs. of coal per hour to obtain 8 knots, whereas the James Stevens No. 3 only barns 2 cwt.

1 qr. 23 Ibs. to obtain 8J knots per hour.

The type of engine required for driving the screw propeller is much more com- pact, and weight for weight is not heavier when compared with the speed obtained.

The engines of the Queen being almost horizontal, while those of the James Stevens No. 3 are miniature vertical inverted compound surface condensing engines of a very strong design, made to stand full power driving in the worst weather.

On driving the vessel (James Stevens No. 3) against a head sea (point 2), it was found that there was not the least sign of the engines " racing " ; this being due to the position of the propeller and to the cavity in which it is placed being air-tight; the propeller under these con- ditions keeps the cavity fall of water owing to its action in expelling the air and forming a partial vacuum, thus drawing the water up and keeping the propeller immersed. Again, the screw propeller in its position in the cavity reduces the possibility of foaling to a minimum (point 1), and even in the event of anything of that sort occurring access to it is rendered very easy to clear the obstruction by an opening in the top of the cavity provided for that purpose.

This hatch can be seen immediately above the screw in the profile and deck plan, page 273.

At the trials in the Solent and subse- quently on her passage to Grimsby it was found that the James Stevens No. 3 manoeuvred very satisfactorily (point 3) both with rudder and engines, the latter working in response to an engine-room telegraph placed conveniently to the hand of the coxswain. In the event of the rudder being damaged sweep oars have been provided, and it was found that at moderate speed the boat could be kept under control by their use.

So far for the comparison of the two methods of propulsion, and, judging from it, it would certainly appear that the Institution has been right in attempting a new departure.

A Wiers feed-pump has been fitted to the new steam Life-boats with satisfactory results. The patent water-tube boilers are those of Messrs. White and Foster, and can supply steam to sustain an average speed of 8 knots on about inch of air- pressure, and it should be borne in mind that the ordinary full-power driving of the Queen requires an average air-pressure of -| in. to 1£ in., therefore the contrast in favour of the new boat's boiler is very marked.

The experiment made in burning oil fuel in the Queen has not come up to expectations, and consequently it has not been repeated in the new boats.

An evaporator (Webster's) is fitted, and on being tested it was found that it could yield at the rate of about 3 tons of good soft water in 24 hours: a very satisfactory result, as it obviates the necessity for taking the boat to a hydrant to fill up with water, for there is some- times considerable difficulty in doing this, and the nearest watering-place is often at a distance from the moorings.

The following additional particulars of the new Steam Life-boats may also be of interest:— Size of Engines.—H.P. cylinder 9 in. diameter, L.P. cylinder 16 in. diameter, stroke 9 in.

Dimensions of Boiler.—Grate area 15 sq. ft., beating surface 500 sq. ft.

Working pressure.—150 Ibs.

Particulars of propeller.—4 blades, 8ft. IJin.

diameter, 3 ft. 6J in. pitch..