1901.) | MARINE REVIEW. oo 21 CONSTRUCTION OF TORPEDO BOATS AND DESTROYERS. BY GEORGE HERBERT WILSON. CONSTRUCTION OF RUDDERS. Having outlined the various features of the rudders shown on plates 8, 9 and 10, I will continue along that line and present a somewhat differ- ent type of rudder in plate 11. A photograph of this rudder when com- plete is also shown. Probably the most radical difference in the construc- tion of this rudder is in the material of which it is made, namely, cast steel. This is somewhat of a departure from the wrought materials used in the building of the other rudders, but it has been found satisfactory in a great number of cases and has proved its efficiency as applied to this service. From the nature and strength of this material the dimensions must be increased over those used when wrought material is employed. This, of course, entails additional weight, but compensation is gained by the decrease in cost. Following the practice previously mentioned, the stock was cast in one piece with short stumps projecting to form the arms of the rudder. This is done to allow for turning in the lathe and for boring. Extension pieces for the arms and part of the frame were also made of cast steel. These were joined to the stumps by a deep rabbet, well riveted, making a very rigid connection. . The boring of the rudder stock allows of a considerable saving in the weight, but I question the advisability of the practice. Considering the increase in expense and the possibility of weakening the stock either by a crooked bore or by enlarging some unknown blow hole it would seem to be the best plan to' adhere to the solid stock. 'Cast steel at its best is somewhat risky and when employed in the construction of so important a part of a boat too much care cannot be displayed in the work. At the upper end of the stock the necessary collars and keyways were turned and cut and in the wake of the bearings the stock was faced. In the wake of the lower bearing, a brass sleeve was shrunk on the stock. This sleeve was made to fit well down in the fillet between the rudder stock and the rudder frame, and was tapered at its upper edge. In shrinking the sleeve on the stock it was found, when cool, to have drawn away from the fillet. This was due to the tapered end cooling off first and binding on the stock, causing the sleeve, when cooling, to shrink toward that end. This can be obviated by making both ends alike. When the sleeve drew away from the fillet, a matter of about 1-16 or 3-32 in., sheet brass was worked in, making a very tight fit, and answering all the requirements. The usual method of fitting the side plates was followed--two plates on each side with a lap in the center. Regarding the question of material for filling the spaces between the rudder arms, it was decided, after due consideration, to eliminate all filling substances, thus making the rudder a sort of a tank. This means a saving of about 400 lbs., an item of no little consequence, especially when having such a trimming moment. In order, however, to insure the protection to the plates on the inside of the rudder, it must be made thor- oughly water tight, and to know this, it must of course be tested. Al- though all the parts were well coated with paint, it seemed unwise to use water for the test, on account of its attacking the rivets and taps. Air was suggested, but was discarded on account of inaccuracy in locating leaks. I suggested that oil under a nominal pressure would answer all the test purposes and likewise act as a protective coat on all the internal parts. The rudder therefore was tested in this manner. The tests were very satis- factory and very few leaks were found which were easily caulked. In rudders of this type it seems that there is useless expense and in- creased weight involved in filling them in solid when they can be built to withstand all the outward pressures, and as the plating is generally of about the same thickness as that of the hull in this vicinity, the danger from puncture or dents is not much greater. Testing under pressure gives an idea as to the resistance of the plating and as in the actual conditions the plates are better supported, there can be little doubt as to their ability to stand the pressure. In the outlines of the different rudder construc- tions given in the previous article and in this, it seems that the best types to follow in the two cases--overhung and protected--is the first one pre- sented for the former type, and the one shown in plate 11 of this article for the latter. In the rudder shown in plate 8 the suggestions for the modifications would be along the lines of making the stock and frame of cast steel and of making the rudder hollow instead of filling in with wood, The rudder describea in this article and shown on plate 11 is shown in the photograph ready for putting in place. STEAMSHIP PINNA FITTED WITH OIL FUEL BURNERS. The steamship Pinna, belonging to the Shell Transport & Trading Co., the largest tank steamer afloat, carrying some 9,000 tons of oil and stores, has had her boilers, both main and auxiliary, fitted with Orde's oil fuel burners. The Pinna is 420 ft. long, 52 ft. beam and 32 ft. 2 in. deep. She was built by Sir William G. Armstrong, Whitworth & Co. oi Newcastle, England. Her trial lasted three hours. The oil fuel apparatus worked very well in spite of the fact that 10 per cent. of water was present in the oil. Borneo oil was used. The engines were made by the North Eastern Marine Engineering Co., the cylinders being 28 in., 46 in. and 77 in. diameter with a stroke of 48 in., and the pressure 180 lbs. per square inch. Accompanying this article is an illustration of the oil e a \ 1 Mee See t 1 oo AUXILIARY BOILER, STEAMSHIP PINNA. burning apparatus as fitted to the auxiliary boiler. The main boiler ar- rangements for oil fuel are exactly the same, except that double or duplicate burners are fitted to each furnace. Mr. Orde's plan for burning oil fuel is to heat the oil in the uptake and to produce it at the burners in a volatile condition, at the same time combining with the superheated air and steam. The boilers can be worked either with coal or oil fuel. When the latter is used the fire bars are covered with broken brick or other matter. This bed of brick gets white hot and forms an incandescent bed, which, when the spray of oil is injected upon it, adds very greatly to the efficiency of the arrangement. ce GAS BUOYS IN ST. MARY'S RIVER. Mr. Charles H. Keep, secretary of the Lake Carriers' Association, has received the following letter from Capt. W. Maynard, naval secretary of the light-house board: "Referring to your letter of April 24, 1901, relative to a memorandum lately filed by the Lake Carriers' Association with the light-house board concerning the necessary gas buoys in the St. Mary's river, Mich., the board states that with the facilities at its disposal for taking care of gas buoys it will not be able to provide at present all the gas buoys that have been asked for in your memorandum. It has, however, authorized the inspector of the eleventh light-house district to place, as soon as possible, the following-named gas buoys: "A gas buoy at Stribling point to mark the beginning of a turn for up-bound vessels as indicated on the chart submitted by the Lake Carriers' Association. ; "A gas buoy at Dark Hole, above Sailors' encampment, to mark a turn for down-bound vessels as indicated on the same chart."