COMPARATIVE RESULTS IN STEAM AND COAL CONSUMPTION. 159 



The method adopted for coal consumption test was to bag and weigh 

 coal as it was needed. 



Canvas bags with a capacity of about 200 pounds were used. These 

 were filled in the bunkers and weighed by spring balance in the engine-room. 



The usual precautions of calibrating balance, recording condition of 

 fires at beginning and end of test, measuring water glasses and bringing 

 boiler pressure to the same point were of course taken. 



After the first eight hours two fires were cleaned each watch and the 

 ashes pumped overboard through the ash ejector. All the usual auxiliary 

 machinery was in use, ice machine being run about ten hours, sanitary 

 pumps, dynamos, etc. 



I append a tally sheet of two of these tests which shows how the weights 

 of the bags varied. At the same time we made water measurements to 

 help us determine whether the failure in economy was due to faults in the 

 boilers or the machinery. 



A water meter was installed but the results seemed so unreasonable 

 that a check method was used by pumping all the condensed water by 

 means of one of the feed-pumps which was controlled by a float in the hot 

 well through a hose, and the output measured in barrels, the other feed- 

 pump meantime feeding the boilers from the reserve tanks. 



The Vanadis propellers had been partially standardized on the Clyde 

 and several runs had been made in Glen Cove to determine the required 

 number of revolutions to 13 knots. In the following spring, however, a 

 complete standardization test was run at Provincetown, the various records 

 of which are appended. 



It will be noticed that the best test showed a consumption of 33 tons 

 or 27 per cent, more than the guarantee. In view of this unfortunate 

 condition it was possible to do one of three things:— 



1 . Lengthen the vessel to increase bunker capacity. 



2. Remove turbines altogether and replace by twin reciprocating 

 engines. 



3. Remove the center high-pressure turbine and replace by a recipro- 

 cating engine, exhausting into the two low-pressure. 



No. 3 was decided on. The contract for this alteration was let to the 

 Staten Island Shipbuilding Company, and completed in January, 19 10. In 

 May following the vessel was run without propellers on the turbine shafts, 

 being driven by the center propeller only, over the Glen Cove course, and 

 subsequently a 4-hour water consumption test was run at the revolutions 

 required for 13 knots. The vessel was then re-drydocked and the turbine 

 propellers fitted to the wing shafts, and in July of the same year the com- 

 plete standardization coal and water tests were run in the new condition. 



