The U.S. torpedo boats Bagley, Barney and Biddle were designed and built by the Bath Iron Works, Bath, Maine, in conformity with the circular issued to bidders defining the characteristics of sixteen torpedo-boat destroyers and twelve torpedo boats. These three vessels are the only ones of the twelve torpedo boats that were built entirely from the contractors' plans and specifications, the others being built from those prepared by the Navy Department.
The new torpedo-boat TB-24 Bagley was named after Ensign Worth Bagley, the first United States' naval officer to be killed in the Spanish-American War while fighting aboard the torpedo-boat Winslow.
The armament consists of three 3-pounder semi-automatic R.F. guns and three tubes for short 18-inch Whitehead torpedoes. Ample ammunition is carried for the guns, and there is provision for carrying five torpedoes. There is a conning tower forward, made of half-inch nickel-steel with a searchlight mounted on top of it. The vessels are very lightly constructed, and still are exceedingly strong. The freeboard is considerably lower than that used on the torpedo boats of the Department's design, appreciable weight being saved by this reduction.
There are eleven large watertight compartments, separated by transverse bulkheads. Some of these compartments are further subdivided by longitudinal bulkheads, making a total of fifteen watertight divisions in all. The two compartments at the middle of the boat are occupied by the main engines with their condensers and auxiliaries. Just forward and just aft of these are the boiler compartments, each containing one boiler and the usual fire room auxiliaries. Coal bunkers having a total capacity of forty-seven tons are located on each side of the boilers and on one side of each engine room.
The two compartments forward of the forward boiler are occupied by the crew, while the one just aft of the after boiler is devoted to the officers, and the one aft of that to the petty officers. Accommodations are provided for three officers and twenty-six crew. Steam heat is fitted in the living spaces. There is a combined hand and steam-steering gear, and a steam windlass made by the Hyde Windlass Company. There is also an electric-light plant of about sixty lights capacity, including a searchlight.
The sizes of the engines are, high-pressure cylinder, 17.22 inches; intermediate pressure, 24.78 inches ; low pressure, 37.37 inches, with a common stroke of 21 inches. These engines are capable of working up to 335 revolutions per minute, but it was not found necessary in these vessels to drive them at such a high number of revolutions to obtain a speed considerably in excess of the contract requirements.
There are two Normand water-tube boilers, each having a grate 9 feet and 6 inches long and 6 feet 3 inches wide, with a heating surface of 2,800 square feet, supplying steam to the engines at a pressure of 230 pounds to the square inch. There are two condensers, one being in each engine compartment. Each condenser has a cooling surface of 1,183 square feet. The tubes in these condensers are curved and expanded into the tube sheets, thus overcoming the usual difficulty with leaky tubes, and increasing the efficiency of the condensers. Sea water is circulated through the condensers by means of scoops, the motion of the vessel being sufficient for the circulation without any pump being in use. There is, however, a small circulating pump supplied for each condenser for use when the vessel is standing still.
The air, feed and bilge pumps are driven by shafts taking their motion from the intermediate crosshead of each main engine. The feed water from the main feed pumps is sent through closed heaters on its way to the boilers. These heaters take their steam from the low-pressure steam chests at the working pressure of those chests, which at full power is from 22 to 28 pounds. The heaters are very efficient; they raise the temperature of the feed water about 115 degrees, it being delivered to the boilers between 225 and 240 degrees Fahrenheit, The main engines are all steam jacketed, both barrels and heads, and steam is used at boiler pressure for this purpose, except in the case of the low-pressure barrel jackets, which are supplied from the intermediate steam chests at a pressure of about 90 pounds, and drain back to the same chests. The steam for the other jackets is taken from the bottoms of the separators at the main engine throttle valves, and after passing through the jackets is used to drive the blower engines. The exhaust from these blower engines can be turned either into the condensers direct or into the low-pressure stearn chests, by means of valves provided for turning the auxiliary exhaust into one of these discharges or the other, as desired.
While the piping is arranged so that both boilers can supply steam in common to both engines, and so that either boiler can supply steam to both engines, in case of running a single boiler, yet the way that this piping is designed to be used in full power service, or any service where both boilers are in use, is to entirely separate the forward boiler, forward engine and condenser from the after boiler, after engine and condenser, thus making two independent steam plants in the vessel. This system avoids the usual difficulty in maintaining a constant level of water in the boilers, because each boiler, engine and condenser, with the coupled pumps, form a closed circuit having a constant amount water in it, which amount is only reduced by leakage. In orderto make up for this leakage, a small pipe is led from the reserve feed tank to the condenser and a valve on this pipe is under the control of the water tender in the fire room. By this means, the amount of water turned into the condenser from the reserve-fee tank can be regulated so that it just equals the amount lost leakage, and the water level in the boiler remains absolutely constant.
Each fire room is fitted with a 55-inch blower, a Davids ash ejector and an auxiliary feed pump capable of feeding boilers at their maximum capacity. Each engine room is provided with an evaporator having capacity of 1,000 gallons in 24 hours, and the after engine roo is fitted with a distiller having a capacity of 1,000 gallons.
Absolutely constant height of the water in the boiler is obtained without any feed regulators. This enables the boilers to steam uniformly at their maximum capacity at all times, because the boilers are not pumped full of cold water one minute and nearly empty the next. The combustion is carried on at all times at its utmost rate, with the firemen perfectly at their ease and having the confidence which is given by a constant and adequate supply of water to the boilers. The water is fed to the boilers at a temperature averaging 235 degrees Fahrenheit. The engines are exceedingly long stroke and steam jacketed by a simple system which is far more efficient than the usual complicated method involving reducing valves and traps. The jacket steam is used to drive the blowers.
The engines are of the three-cylinder type instead of the four, thus having considerably less cylinder wall for condensation and re-evaporation in proportion to the volumes of the cylinders. The use of the three-cylinder engines is made without the corresponding loss of balance so frequently claimed to be inherent to this type of engine. The running parts of each cylinder are made as nearly as possible the same weight, with the result that the balance is far better than that obtained with the four-cylinder engine, with the cranks opposite. The clearance spaces are very small, being 11.7 per cent, in the high pressure, 15.7 per cent, in the intermediate and 7.8 per cent, in the low-pressure cylinders.
The official speed trials of these three vessels were all conducted without the slightest accident of any kind, and the contract speed was exceeded with the the greatest ease. Each vessel had her propellers standardized on the measured mile at Southport, Maine, and the revolutions per minute found necessary to propel the vessels at 28 knots when loaded as required by the contract. In rough water they frequently jumped so that from twenty to thirty feet of the forward part of the keel was entirely out of water, and things were very wet on deck. The average indicated horsepower for the two-hour run was 3,910.
It was neccessary to replace the weights consumed during the standardization trial and to compensate for the coal which would be consumed in getting up to speed before the official two-hour run began. The boilers and fires were not cleaned between the standardization trial and the two-hour run. The Biddle was at no time driven to anywhere near her maximum speed. The speed of the engines was adjusted so that the vessel would maintain a speed slightly in excess of 28 knots, and the quantity of steam supplied by the boilers was regulated by the speed of the blowers, no attempt being made to force her. The safety valves popped frequently during the entire two hours. The average indicated horsepower for the two-hour run was 3,650.
In smooth water these vessels do not lift the fore foot out of water as torpedo boats usually do. The change of trim on these vessels is 52 inches at full speed. The entire designed water-line length is available at full speed, so that the resistance of the vessels does not increase as fast in proportion as does that of some other types.
The load carried on trial by these vessels was not reduced in any way from that originally contemplated by the contract. All three of these vessels finished the two-hour trial in perfect condition to run another hour had it been necessary, and in fact the boats were run at full speed for a considerable time after the two hours had elapsed in order that turning trials might be made at full speed. There was no flaming at the stack on any of these vessels.
The coal consumption per indicated horsepower was exceedingly low on all of them. These figures, obtained while burning from 55 to 65 pounds of coal per square foot of grate per hour, were truly wonderful and were without parallel in the history of torpedo-boat construction in this country or in England. The consumption of coal was very accurately determined, as all the coal used was carried in bags holding 76 pounds each, and the number of bags emptied on the official two-hour speed trial was recorded by the naval officers connected with the trial and checked by the contractors. This low coal consumption is the secret of speed in these vessels, and, taken in conjunction with the remarks previously made concerning steam economy of this class of machinery, makes the strongest plea possible for its use on all fast vessels, either torpedo boats or yachts.
A progressive trial was made of the torpedo-boat Barney on December 1, 1900, when she had been overboard 126 days, lying in the water of the Kennebec river, which is brackish and having a maximum density at high tide of about 1.013. During this interval of 126 days, the Barney was run out at sea about fourteen times, the trips averaging not over six hours each. She was hauled out immediately after the trial and the bottom was found to be very rough, but there were no barnacles on it, but the paint had risen into pimples about the size of the end of a lead pencil and they were very close together, there being no smooth places. The Barney's displacement on the trial was 168 tons. This data can therefore be properly compared with that obtained on the Biddle, which is given in the first part of the paper. The Biddle is an identical boat, but the paint was in good condition and the condenser scoops projected on a transverse plane, showed about 20 square inches less area. The Biddle had been over board 35 days when the progressive trial was made.
On 15 May 1901, the torpedo boat Bagley, built by the Bath Iron Works from their own design, made a very successful trial, averaging 29.1 knots for two hours. The contract speed was 28 knots. The trial of the sister boat, Bagley, followed on the 16th May, her average speed being 29.2 knots. The trial of the third boat of the same design, the Biddle, followed shortly.
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