BATTLESHIPS. EXPERIENCE GAINED ON THE JUPITER. 187 



Reliability. — ^Taking these points in their order, the first to be considered 

 would be reliabiUty. The reHability of induction motors and large high-speed 

 turbo-generators for land use has been well known for some time, but up to about 

 one and one-half years ago had not been demonstrated on board ship. However, 

 experience at sea with them has not developed any trouble, and their reliability is 

 now unquestioned. There are several things that go to make an electric installa- 

 tion more reliable than any other. First, the installation is in duplicate through- 

 out and the breaking down of one engine does not affect the ship except at high 

 speed; it might be said that this is true of other installations, but it is not true in 

 the same sense nor in the same degree that it is with the electric drive. For exam- 

 ple, if one turbo-generator breaks down, the ship can still run in a perfectly normal 

 manner up to a speed of about 19 knots. This would be impossible with any other 

 mode of propulsion; even at speeds within the power of one engine on a twin- 

 screw ship the maneuvering qualities would become so bad as to handicap the ship ; 

 in fact a twin-screw ship operating with one engine would be able to reach port 

 safely but would be of very little use in battle, whereas an electrically-driven ship, 

 operating with one turbine, would be just as good as any ship up to a speed of 

 about 19 knots. 



Then, too, there is the question of auxiliaries ; with other forms of propulsion, 

 if the auxiliaries in one engine-room break down, that engine-room may be almost 

 entirely put out of commission. Of course the main air and circulating pumps are 

 cross-connected, but when operating that way they are not very satisfactory and 

 I have seen a battleship forced to stop because the forced lubrication pumps in the 

 starboard engine-room broke down. If the ship had gone ahead with the port tur- 

 bines, the starboard turbines would have revolved and burned out the bearings, so 

 that it was necessary to stop the ship and repair pumps; with the electric drive it 

 would be a simple matter to shift to the other engine-room and make repairs with- 

 out stopping. 



There is one other thing that makes this installation more reliable than other 

 forms of turbine-drive, and that is the fact that the turbine revolves in the same 

 direction all the time. The importance of this cannot be overestimated, as it is 

 believed by operating engineers that the greater amount of blading trouble that 

 ships have had is nearly always due to the distorsion that occurs when backing. 

 There is also one other advantage when compared with reciprocating engines, and 

 that is that the turbines would be much less susceptible to damage by water when 

 the boilers are priming. This fact has been thoroughly demonstrated by experi- 

 ence on the Jupiter. 



Maneuvering. — As regards maneuvering qualities, it is believed that the elec- 

 tric drive is far superior to any other method. This point will be taken up more in 

 detail when the Jupiter's installation is discussed. It is rather difficult to describe 

 these advantages on paper, but very easy to appreciate them when you see the ma- 

 chinery working. Instead of big, heavy throttles to open and close, there are light, 

 easily handled oil switches, and a speed controller that can be handled with one 



