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Design of Merchant Ships The Question Discussed Before the Institution of Naval Architects from the Owners' Point of View WMHE author sets out to analyze -- the influence exerted by ship- owners upon the design and construction of ships, basing these ob- servations upon 30 years' experience with the Cunard Steamship Co., and dealing mainly, therefore, with ships suitable for the North Atlantic trade. This trade is the subject of very keen SECTION SHOWING WATERTIGHT BULKHEAD WITH FIRE SCREEN BULK- HEAD IN UPPER DECKS, passenger ship will run without be- coming an economic drag. A fast vessel, primarily built for passenger service, can be made of little profit- able use if converted into a cargo carrier. The accompanying table shows the general particulars of in- teresting vessels of the Cunard fleet, and at the same.time indicates the SECTION SHOWING TYPICAL . ARRANGEMENT OF WEBS, BUTTRESSES, AND PILLARS. IN PLACES WHERE THERE ARE NOT CONTINUOUS BULKHEADS --------_poar OECK BUTTRESSES SUPPORTING OECK HOUSES \GIRDER P y IRDER i STRONG DECK : a NN NS NX ' 1 SS \ SGV --4z-----4 \N \ ie. GIRDER S N oe pa oe | ees : % , \ ec 4 Fine ote S SS SS S \ \ 2 \ Mes RG S WG N SV SS Bes Bes NN ANN A \ \\S WN GIRDER SX Dic \CERRAK a fi peel i Ne = S1'o1 oi K . GW S WAG Se rio! CRESS WIN Gos Z| RRR \ bet \ \ -- e ug ~~ - <i ¢ \\NS \ S ee co \ "3 Es S\ * c a Se x! #1 Pek SS \ , BOILER)' ROOM \ RS at} " dM Cee 3 \' Bee swro jf \\ ate . Sina . Sy, Sa SS MO it Mine : Me a ->k- ee ee me NN Sections of the new Cunarder " Aquitania."? international competition, and thus the owner has been willing to put to a commercial test the various improve- ments which have been made by the engineering profession. This has add- ed other difficulties in determining the general features of new designs, one of these difficulties being that of estimating with accuracy for how long a period a particular type of *Condensed from a paper read bef Institute of Naval Dechieae. nae rapid rate of progress that has been maintained by this premier line. Mr. Peskett enumerates the varying considerations that have to be taken into account in the initial stage of a design, which should be developed from the owner's experience and data, if the finished ship is to prove a suc- cessful commercial asset. The his- tory of the Lusitania and Mauretania design is sketched. The splendid re- sults of these ships on service speak By L. Peskett for themselves, and indicate the ju- dicious manner in which the available data were employed. Referring to turbine machinery, the author draws attention to the bold experiment made by the Cunard Co. in building the Caronia and Carmania of equal dimensions, the former being fitted with quadruple-expansion recip- rocating engines and twin-screws, run- ning at 80 r. p. m., while the latter is fitted with compound turbine en- gines driving triple engines at 175 revolutions. The results of eight years' experience with these ships do not warrant the adoption of direct acting turbines to drive a ship of this type at a speed of 18 knots. The considerations leading to the design of the Aquitania are extremely interesting. In this case the problem was that -of designing a ship capable of working on the mail service with the Lusitania and Mauretania, and at the same time one that would make as much per voyage without subsidy as the express steamers were making with one. This involved the con- struction of a ship which could sail regularly from either terminal port once every three weeks, and not take longer than 514 days on the voyage. For this purpose a speed of 23 knots was decided upon. The problem of earning the extra profit led to the in- creased dimensions of the new ship. With regard to watertight subdi- vision, Mr. Peskett states that the Cunard Co. are satisfied that for ships of the type of modern high-speed liners a combination of longitudinal and transverse bulkheads is the best suited to their requirements, from the point of view of strength, safety, and convenience. In view of the interest attaching at the present day to the question of unsinkableness, the dia- grams on page 198 showing the reé- sults of flooding under assumed con- ditions, are very instructive, and in- dicate that the question has been solved in this case. Intermediate ships do not lend themselves to this combination of longitudinal and trans- verse subdivision, and are most con- veniently subdivided by transverse bulkheads only. Scarcely less important than water- tight subdivision is protection against