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*

[

]

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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