UFC 4-159-03
3 October 2005
Cyc = C 0 + (C1 - C 0 ) * (T / d) K
(11)
EQUATION:
deepwater current force drag coefficient for T/d ≈ 0.0;
where
CO
=
this deepwater drag coefficient is estimated from:
C 0 =0.22 * χ
(12)
EQUATION:
where χ is a dimensionless ship parameter calculated as:
χ =LwL 2 * Am / ( B *V )
EQUATION:
(13)
LwL = is the vessel length at waterline (m)
where
Am = is the immersed cross-sectional
area of the ship at midsection (m2)
B = is the beam (maximum ship width at
the waterline) (m), and
V = is the submerged volume of the ship, (m3)
(which can be found by taking the
displacement of the vessel divided
by the unit weight of water, given
in Table 4-1).
C1 = shallow water current force drag coefficient
where T/d = 1.0; for currents of 1.5 m/s
(2.9 knots or 4.9 ft/sec) or less; C1 = 3.2 is recommended
T = average vessel draft (m)
= water depth (m)
d
K = dimensionless exponent; laboratory data from
ship models shows:
K=2
Wide range of ship and barge tests; most all
of the physical model data available can be
fit with this coefficient, including submarines.
K=3
From a small number of tests on a fixed
cargo ship and for a small number of tests
on an old aircraft carrier, CVE-55
K=3
From a small number of tests on an old
submarine hull, SS-212
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