UFC 4-159-03
3 October 2005
Table 4-7. AR for Major Vessel Groups
SHIP
AREA RATIO, A R
Destroyer
100
Cruiser
160
Carrier
125
Cargo
240
Tanker
270
Submarine
125
Note that in these and all other engineering calculations discussed in this
UFC, the user must be careful to keep units consistent.
EXAMPLE: Find the longitudinal current force with a bow-on current of θc=180 degrees
with a current speed of 1.544 m/sec (3 knots) on a destroyer in salt water with the
characteristics shown in Table 4-8.
SOLUTION: Table 4-9 shows the predicted current forces. Note that these forces are
negative, since the bow-on current is in a negative "X" direction. For this destroyer, the
force on the propeller is approximately two-thirds of the total longitudinal current force.
For commercial ships, with relatively smaller propellers, form and friction drag produce a
larger percentage of the current force.
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