been made of it, for those well qualified to speak on
the subject consider that careful handling of the ship would, in most
cases, prevent damage to the screws, and that where the exposure is
unusually great, effectual protection by portable protectors presents no
insuperable difficulty.

HIGH SPEED TWIN SCREWS.
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|Ship A.|Ship B.|Ship C.|Ship D.|Ship E.|Ship F.
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Length, ft. | 325 | 315 | 300 | 300 | 220 | 250
Breadth, ft. | 68 | 61 | 56 | 46 | 34 | 321/2
| | | | | |
Draught on trial, | 26 ft | 24 ft | | 15 ft | 12 ft | 13 ft
forward. | 2 in | 6 in | .... | 6 in | 10 in | 1 in
| | | | | |
Draught on trial, | 27 ft | 25 ft | | 19 ft | 15 ft | 14 ft
aft. | 3 in | 6 in | .... | 9 in | 2 in | 7 in
Displacement, | | | | | |
tons. | 9,690 | 7,645 | 5,000 | 3,584 | 1,560 | 1,544
I.M.S., sq. ft. | 1,560 | 1,287 | 1,000 | 744 | 438 | 392
Speed of ship, | | | | | |
knots. | 16.92 | 17.21 | 18.75 | 18.18 | 16.91 | 17
I.H.P. |11,610 |10,180 | 8,500 | 6,160 | 3,115 | 3,045
Revolutions per | | | | | |
minute. | 107.2 | 88 | 120 | 122.6 | 150.4 | 132.1
| | | | | |
Pitch of | 19 ft | 22 ft | 18 ft | 17 ft | 12 ft | 14 ft
screw. | 5 in | | 9 in | 6 in | 71/2in | 9 in
| | | | | |
Slip. per cent | 17.6 | 10 | ... | 14.2 | 9.7 | 11.4
| | | | | |
Diameter of | 15 ft | 18 ft | 14 ft | 13 ft | 10 ft | 11 ft
screw. | 6 in | | 6 in | | 6 in |
| | | | | |
Diameter of | 4 ft | 4 ft | 3 ft | 3 ft | 2 ft | 2 ft
boss. | 4 in | 11 in | 9 in | 5 in | 9 in | 10 in
Number of blades | 4 | 4 | 3 | 3 | 3 | 3
Blade area of one | | | | | |
screw.