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.             |   72  |   87  |   60  |   47  |   24  |   24
Shape of blade.     |Fig. 2.|Fig. 3.|Fig. 2.|Fig. 2.|Fig. 4.|Fig. 4
Pitch              |       |       |       |       |       |
----------          |  1.25 |  1.22 |  1.3  |  1.34 |  1.2  |  1.34
Diameter            |       |       |       |       |       |
Disk              |       |       |       |       |       |
--------            |  2.62 |  2.92 |  2.75 |  2.82 |  3.6  |  3.96
Blade area          |       |       |       |       |       |
Immersion of        |  9 ft |  5 ft |       |  4 ft |  2 ft |  1 ft
screw.            |       |  3 in | ....  |  4 in |  9 in | 10 in
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The slips of these screws vary from 10 to 171/2 per cent., which is certainly not an extensive range, considering the widely different working conditions.  Slip, as an indication of the efficiency of the screw, is not only an interesting subject, but it is often one of importance.  In these ships, however, there is nothing about the slips which would give rise to any doubts as to the fitness of the screws for their work.