UFC 4-159-03
3 October 2005
The transverse wind force drag coefficient depends upon the hull and
superstructure of the vessel and is calculated using the following equation, adapted
from Naval Civil Engineering Laboratory (NCEL), TN-1628, Wind-Induced Steady Loads
on Ships.
[
]
EQUATION: Cyw = C * ((0.5(hS + hH )) / hR )2 / 7 AS + (0.5* hH / hR )2 / 7 A H / A Y
(3)
where
transverse wind force drag coefficient
C yw =
empirical coefficient, see Table 4-2
C
=
h R = 10 m = reference height (32.8 ft)
h H = A H / L wL = average height of the hull, defined as
the longitudinal wind hull area
divided by the ship length at the
waterline (m)
longitudinal wind area of the hull
AH =
(m2)
ship length at the waterline (m)
L wL =
height of the superstructure above the
hS =
waterline(m)
longitudinal wind area of the
AS =
superstructure (m2)
A recommended value for the empirical coefficient is C = 0.92 +/-0.1
based on scale model wind tunnel tests (NCEL, TN-1628). Table 4-2 gives typical
values of C for ships and Figure 4-3 illustrates some ship types.
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