| Name | Length | Breadth | Moulded draught | Midship area | Dist. | Indicated H.P. | Speed | Block coefficient | Midship section coefficient | Prismatic midship section coefficient |
|
| Kirk's system | Coal consumption | Cylinders | Boilers | Working Pressure | ||||||||||
| Length of entrance | Angle | Per day | Per I.H.P. | Diameter | Stroke | Heating surface | Bar surface | ||||||||||||||||||||
| ft. in. | ft. in. | ft. in. | Ins. | Ins. | Lbs. | ||||||||||||||||||||||
| City of Rome | 542 6 | 52 0 | 21 5½ | 1031 | 11,230 | 11,890 | 18.235 | .649 | .925 | .702 | 255 | 201.3 | 161.27 | 8° 29' | 185 | 2.2 | {3 @ 46 } {3 @ 86 } | 72 | 29,286 | 1398 | 90 | ||||||
| Normandie | 459 4 | 49 11 | 19 9¾ | 892 | 7,975 | 6,959 | 16.66 | .614 | .901 | .681 | 265 | 219.5 | 146.41 | 8° 44' | 148 | 2 | {3 @ 35 7/16} {3 @ 74 7/8} | 67 | 21,404 | 756 | 85.2 | ||||||
| Furnessia | 445 0 | 44 6 | 22 2½ | 893 | 8,578 | 4,045 | 1 14 | .682 | .903 | .755 | 284 | 273 | 108.7 | 10° 28' | 97 | 2.2 | 49-100 | 66 | 10,396 | 440 | 90 | ||||||
| Arizona | 450 0 | 45 1½ | 18 9 | 758 | 6,415 | 6,300 | 17 | .589 | .895 | .658 | 269.2 | 217 | 153.79 | 7° 30' | — | — | {1 @ 62 } {2 @ 90 } | 66 | — | — | 90 | ||||||
| Orient | 445 0 | 46 0 | 21 4½ | 904 | 7,770 | 5,433 | 15.538 | .621 | .919 | .676 | 270.8 | 225 | 144.17 | 8° 21' | — | — | {1 @ 60 } {2 @ 85 } | 60 | — | — | 75 | ||||||
| Stirling Castle | 420 0 | 50 0 | 22 3 | 990 | 7,600 | 8,396 | 18.4 | .569 | .889 | .639 | 286.8 | 233.7 | 151.3 | 8° 22' | — | — | {1 @ 62 } {2 @ 90 } | 66 | 21,161 | 787 | 100 | ||||||
| Elbe | 420 0 | 44 9 | 20 0 | 807 | 6,350 | 5,665 | 16.571 | .591 | .901 | .655 | 275.5 | 229 | 144.6 | 7° 56' | — | — | {1 @ 60 } {2 @ 85 } | 60 | — | — | — | ||||||
| Pembroke Castle | 400 0 | 42 0 | 17 0 | 648 | 5,130 | 2,435.8 | 13.25 | .623 | .623 | .692 | 284 | 258 | 122.9 | 8° 49' | 44 | 1.7 | 43 and 86 | 57 | 7,896 | 288 | 99 | ||||||
| Umbria and Etruria | 500 0 | 57 0 | 22 6 | 1090 | 9,860 | 14,321 | 20.18 | .538 | .896 | .637 | 260 | 191.8 | 184 | 6° 52' | 315 | 2.1 | {1 @ 71 } {2 @ 105 } | 72 | 38,817 | 1606 | 110 | ||||||
| Aurania | 470 0 | 57 0 | 20 0 | 1020 | 8,800 | 8,500 | 1 17.5 | .575 | .942 | .632 | 266 | 204.6 | 170 | 8° 38' | 215 | 2.2 | {1 @ 68 } {2 @ 91 } | 72 | 23,284 | 1001 | — | ||||||
| America | 441 8 | 51 3 | — | — | 6,500 | — | 1 17.8 | — | — | — | — | — | — | — | 185 | — | {1 @ 63 } {2 @ 91 } | 66 | — | 882 | — | ||||||
| Oregon | 501 0 | 54 2 | 23 8 | 1150 | 11,000 | 13,300 | 18.3 | .599 | .849 | .67 | 227.9 | 190 | 164.3 | 9° 39' | 310 | 2.2 | {1 @ 70 } {2 @ 104 } | 72 | 38,047 | 1428 | 110 | ||||||
| Servia | 515 0 | 52 0 | 23 3½ | 1046 | 10,960 | 10,300 | 1 16.9 | .610 | .862 | .71 | 231 | 192 | 145.3 | 10° 42' | 205 | 2 | {1 @ 72 } {2 @ 100 } | 78 | 27,483 | 1014 | — | ||||||
| Scotia, P.S. | 369 0 | 47 6 | 19 9 | 867 | 6,000 | 4,632 | 1 14.31 | .605 | .92 | .65 | 208.9 | 186 | 126.8 | 13° 21' | 168 | 3.4 | — | — | — | — | |||||||
| Alaska | 500 0 | 50 0 | 21 0 | 949 | 9,210 | — | — | .614 | .904 | .679 | — | — | 160.23 | 8° 2' | — | — | {1 @ 68 } {2 @ 100 } | 72 | — | — | 100 | ||||||
| Aller | 438 0 | 48 0 | 21 0 | 907 | 7,447 | 7,974 | 17.9 | .590 | .899 | .656 | 277 | 225 | 150.6 | 8° 10' | — | — | {1 @ 44 } {1 @ 70} {1 @ 100 } | 72 | 22,630 | 799 | 150 | ||||||
| Ems | 430 0 | 46 10 | 20 7½ | 877 | 7,030 | 7,251 | 17.55 | .593 | .907 | .652 | 273 | 223 | 149.4 | 8° 40' | — | — | {1 @ 62 } {2 @ 86 } | 60 | 19,700 | 780 | 100 | ||||||
1 Mean speed of a voyage across the Atlantic Ocean.
The author next considered the strains to which a ship is exposed, and stated that he had before him the calculations for three of the largest vessels, two of them of iron and the other of steel; and he found, in the case of the iron, the maximum tension on the gunwale during the greatest hogging strains likely to be endured at sea would not exceed about six tons per square inch, while in the case of the steel ship it is only about 6½ tons. These strains are well within the limits of safety, and a comparison of the scantlings of these with the others justifies the assertion as to their general safety from a structural point of view. The sections of these three ships are shown in Figs. 1, 2, and 3, with their principal scantlings. It will be seen from these sections that the three ships differ materially in their mode of construction. In the case of Fig. 1, which represents the City of Rome, the largest of the three, it will be seen that the main framing of the vessel is entirely transverse, with very heavy keelsons in the bottom, and large partial bulkheads or web frames, and the outside plating arranged on what is termed the edge to edge principle, with a great portion of it double. In the next section, Fig. 2, the Servia, which is built of steel, on the other hand, the bottom is built on the longitudinal cellular system, the first application, he believed, of this system to an Atlantic liner. The plating of the Servia is of the usual alternate outer and inner strake system, partly double; while the third section, the Oregon, approaches more nearly to the ordinary system of framing and plating usually adopted, but it will be seen that she was well tied in the bottom by very heavy intercostal and plate keelsons, as well as in the top by heavy stringers and sheer strakes, with much of her plating doubled, and heavy web frames inside. The author next considered the question of stability, and went on to deal with the subject of twin screws, and stated that the Barrow Shipbuilding Company has done more in the way of planning and designing for the adoption of twin screws lately than for any other mode of propulsion, and this chiefly for passenger steamers. He did not attach much importance to the particular form of the blade either in single or twin screws, as he believed so long as the disk area, the surface, and pitch were properly adjusted to the speed of the vessel, and to enable the engines to use, at the maximum speed, just the full quantity of steam that the boilers can make, we have got pretty nearly as far as we can get. To fix these dimensions of the propeller accurately at the present time, and without further knowledge of the action of the screw on the water, was, he thought, impossible. All the rules and formulæ are empirical. The best one he knew is given in Table IV., due to Mr. Thom, the head of the Barrow Company's engineering drawing office, and at present acting manager, who has used it for some years in practice. These formulæ are based upon the assumption that the area of propeller disk should be proportional to the indicated horse power, divided by the cube of the speed, and the same with the projected area of the propeller and also the surface.
TABLE IV.
Particulars of Propellers and Constants.
| Ship. | Length of ship. | Disk constant. | Proj. surf. constant | Feet per minute. Speed of tips. |
|---|---|---|---|---|
| City of Rome. | 542 | 220 | 69 | 4,715 |
| Normandie | 459 | 250 | 66 | 4,099 |
| Furnessia | 445 | 223 | 69 | 3,654 |
| Eden | 300 | 211 | 64 | 3,080 |
| Yorouba | 270 | 213 | 63 | 3,202 |
| Taygete | 260 | 238 | 56 | 3,166 |
| Kow-shing | 250 | 171 | 69 | 3,369 |
| S.Y. Monarch | 152 | 221 | 65 | 4,040 |
| S.Y. Aries | 138 | 179 | 56 | 2,986 |
| Twin screw Fenella | 200 | 244 | 64 | 2,890 |
| Twin screw H.M.S. Fearless[1] | 220 | 277 | 67 | 5,022 |
| Twin screw H.M.S. Iris | — | 454[5] | 135[5] | —— |
| Twin screw H.M.S. Iris[2] | 300 | 412 | 221 | —— |
| Twin screw H.M.S. Iris[3] | 300 | 346 | 99 | 4,961 |
| Twin screw H.M.S. Iris[4] | 300 | 439 | 82 | 5,309 |
[1] Estimated with a speed of 17.5 knots and 3,370 I.H.P.
[2] With the first propeller at the estimated speed of 17.5 knots and 7,000 I.H.P.
[3] With four bladed modified Griffith's on actual trial.
[4] With two bladed modified Griffith's on actual trial.