UFC 4-159-03
3 October 2005
EXAMPLE: Find the transverse wind force drag coefficient on the destroyer shown in
Figure 4-5.
SOLUTION: For this example the transverse wind force drag coefficient from Equation 3
is:
[
]
Cyw = C * ((0.5(23.9m + 6.43m))/10m)2/71203m2 + (0.5 * 6.43m/10m)2/71036.1m2 /2239m2
Cyw = 0.940 * C .
Destroyers have extensive superstructure, so a recommended value of C
= 1.02 is used to give a transverse wind force drag coefficient of Cyw = 0.940*1.02 =
0.958.
Note that for cases where an impermeable structure, such as a wharf, is
immediately next to the moored ship, the exposed longitudinal wind area and resulting
transverse wind force can be reduced. Figure 4-6 shows an example of a ship next to a
wharf. For Case (A), wind from the water, there is no blockage in the transverse wind
force and elevations of the hull and superstructure are measured from the water
surface. For Case (B), wind from land, the longitudinal wind area of the hull can be
reduced by the blocked amount and elevations of hull and superstructure can be
measured from the wharf elevation.
Cases of multiple ships are covered in par. 4.6.
72
Previous Page
