Principles of naval engineering - Historic Naval Ships Association

'PRINCIPLES OF NAVAL ENGINEERINGBOILER P ADDLES ENGINEFigure 1-2.— The Demologos :the first steam-driven warship.147.2out more than forty years before. ° The Princetonhad an unusual oscillating, rectangular -pistontype of engine (fig. 1-4). The piston rod was connecteddirectly to the crankshaft, and the cylinderoscillated in trunnions. This ship was also noteworthyfor being the first warship to have allmachinery located below the waterline, the firstto burn hard coal, and the first to supply extraair for combustion by having blowers dischargeto the fireroom. But even the Princeton stillhad sails.Almost twenty steam-driven warships joinedthe steam Navy between 1854 and 1860. One of^In 1802, Colonel John Stevens applied Archimedesscrew as a means of ship propulsion. The first shipthat Stevens tried the screw on was a single-screwship, which unfortunately ran in circles. The secondapplication— a twin-screw shipwiththe screws revolvingin opposite directions—was more successful. JohnEricsson, who designed the Princeton , developed theforerunner of the modern screw propeller in 1837. Itis interesting to note that the original problem withscrew propellers was that they were inefficient at theslow speeds provided by the large, slow engines of thetime. This is just the opposite of the present-dayproblem. Both then and now, the solution is gears:step-up gears, in the old days, and reduction gears,at the present time.these was the Merrimac . Another was thePensacola , which was somewhat ahead of itstime in several ways. The Pensacola had thefirst surface condenser (as opposed to a jetcondenser) to be used on a ship of the U.S.Navy, It also had the first pressurized firerooms.It was not until 1867 that the U.S. Navyobtained a completely steam-driven ship. In theNavy's newly created Bureau of Steam Engineering,a brilliant designer, Benjamin Isherwood,conceived the idea for a fast cruiser. Oneof Isherwood's ships, the Wampanog, attainedthe remarkable speed of 17.75 knots during hertrial runs, and maintained an average of 16.6knots for a period of 38 hours in rough seas.The Wampanog had a displacement of 4215tons, a length of 335 feet, and abeam of 45 feet.The engines consisted of two 100-inch singleexpansioncylinders turning one shaft. The engineshaft was geared to the propeller shaft, drivingthe propeller at slightly more than twice thespeed of the engines. Steam was generated byfour boilers at a pressure of 35 psi and wassuperheated by four more boilers. TheWampanog propulsion plant, shown in figure1-5, was a remarkable power plant for its time.