EM 1110-2-1100 (Part II)
30 Apr 02
Figure II-7-41. Typical vessel-generated wave record
EXAMPLE PROBLEM II-7-5
The period of the diverging waves generated by the vessel.
A vessel is moving at a speed of 10 knots (5.157 m/sec) over water 5 m deep.
The vessel Froude number is
so Equation II-7-23 gives a direction of propagation
θ ' 35.27 [1 & e 12 (0.73&1)] ' 33.88E
and Equation II-7-21 gives a wave celerity
C ' 5.157 cos (33.88E) ' 4.28 m/s
The linear wave dispersion equation can be written
Inserting known values for C, g, and d into the dispersion equation leads to a trial solution for T of 2.8
sec. This is a typical period for vessel-generated waves and demonstrates why floating breakwaters are
usually effective in protecting against vessel waves.