March 18, 1886 ] 



FOREST AND STREAM, 



166 



SAIL PLAN OF SMALL CRUISER " MERMAID.' 1 



we have described, and although the saving in the consumption of 

 fuel over tbe triple expansion type i3 not so great as tbe saving- of 

 the triple expansion over the ordinary compound engine, still, as 

 small economies are becoming more and more important, the advan- 

 tage will probably be sufficient to lead to the use of the quadruple 

 expansion engine, at least in ships intended for long voyages, where 

 economy of fuel is especially of importance. 



During the past year as many as eighteen sets of triple exoansion 

 engines have been manufactured on the Clyde alone, and many 

 others have been turned out on the east coast. Tbe largest set yet 

 fitted to a merchant ship is of 7,000 indicated horse power, and is on 

 board the North German Lloyd's President Meyer. During last- 

 year the old Cunard steamers Parthian and Batavia were refitted 

 with triple expansion engines, and this example is one which the 

 interests of shipowners should prompt them to follow when the ma- 

 chinery of an old ship is in want of renewal. 



The following particulars of the performance of the steamship 

 Yeddo are remarkable for the large saving obtained, although the 

 triple expansion was not here at its best. The Yeddo had been 

 working with two cylinder compound engines, the pressure of steam 

 in tbe boilers being TOlbs. per square inch. There was a large mar- 

 gin of strength in the boilers, and it was decided to increase the 

 working pressure to lOOlbs and fit an intermediate cylinder over the 

 low pressure cylinder, thus convprting the compound engine into a 

 triple expansion engine. The result of this alteration was the reduc- 

 tion of the average consumption of fuel per day on a sea voyage 

 from 17 to 18% tons, or a saving of a little more than 90 per cent, , 

 the speed of tha ship after the alteration being pnctically the same as 

 before. Here there were the same boiler, the same propeller, the 

 same ship, and a similar quality of coal, and improved performance 

 was entirely due to the improved engine. If the steam pressure had 

 been increased to about 140Jbs. on the square inch the saving would 

 have been still more marked. 



Steam pressures as high as ISOlbs. on the square inch have lately 

 been used with triple expansion or quadruple expansion engines, 

 and this is not likely to be much succeeded for some considerable 

 time, for the marine boiler is not well adapted for working under a 

 higher pressure, owing to the thicknesses of furnace and shell plates 

 required for such a pressure, and the ordinary type of boiler is not 

 likely to be readily or easily superceded by a new type. The marine 

 boiler survives numerous competitors in virtue of i s superior fitness 

 for marine work, and as its limit of working pressure has been prac- 

 tically reached there is no reason to apprehend that the type of en- 

 gine now coming into use will be speedily replaced by a much more 

 economical machine. — The Shipping World, March, 1886. 



SAIL PLAN OF THE MERMAID. 



Mast, deck to hounds 19ft. 



Masthead 5ft. 



Topmast, fid to sheave 16ft. 



Bowsprit (outboard) 12ft. 



Bowsprit, rabbet to bee hole lift. 



Boom 23ft. 



Gaff 17ft, 



Spinnaker boom , 25ft. 



No. 1 topsail pole 19ft. 



No 1 topsail club 18.50ft. 



Mainsail, hoist 16ft. 



Boom 22 't. 



Gaff. 16ft. 



Angle of peak 55° 



Foresail, hoist 18ft, 



Foot 10ft. 



Leach ., 17.50ft. 



Jib, hoist 28ft 



Foot 15ft. 



Leach 20ft. 



Working topsail, luff 19.17ft. 



Leach 10.67ft. 



Foot 15 33ft. 



Clubtopsail No. 1, luff 25 6Bft. 



Leach 14.75ft. 



Foot 22.00ft. 



Jibtopsail, luff 33.00ft. 



Leach 20.00ft, 



Foot 14.25ft. 



Spinnaker, luff 35.50ft. 



Leach 36.50ft, 



Foot 26.00ft. 



Areas, mainsail 386.40sq. ft. 



Foresail 87 50^q. ft. 



Jib 142.80sq. ft. 



Three lower sails 616 70sq. ft. 



Working topsail 80.75sq ft 



Clubtopsail 163 52sq. ft. 



Jibtopsail 124.50.sq. ft. 



Spinnaker 46l.50sq. ft. 



Ratio 3 lower sails per sq. ft. wetted surface. . 2.6Ssq. ft. 



Ratio V wetted surface to yd ispla cement in cubic ft. 3.47sq ft. 



Ratio 3 lower sails to square of length of L'.W.L 1 27.- q ft. 



Mainsail (laced foot) and jib (set flying) and working topsail, 10- 

 ounceduck; foresail of 8 ounce, clubtopsail and jibtopsail of heavy 

 drilling, and spinnaker of heavy sheeting. Though she has quite a 

 liberal allowance of muslin, it is not excessive in proportion to tbe 

 bulk of tbe boat, and it is uo arranged that there will be no difficulty 

 1b setting It to suit circumstances. 



