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We analyse spatial patterns and far field properties of the long-wave part of wakes of fast ferries in Tallinn Bay with the use of the Boussinesq-type shallow-water model COULWAVE, forced by realistic ship motions. The calculated heights of ship waves exhibit substantial spatial variability. The largest waves were created when the ship, sailing to Tallinn, entered into supercritical regime when moving over the coastal slope. The maximum wave height eventually reached 3 m, whereas along other sections of the track the wave height was about 1 m. The highest waves hit the area of Pirita Beach that apparently has much larger ship wave loads than the adjacent sections of the Viimsi Peninsula. [ABSTRACT FROM AUTHOR]

The results of a field study of wind waves and ship wakes in the coastal area of Tallinn Bay in the years 2001-2002 are described. The main goal was to identify the typical and extreme parameters of ship wakes and to describe their energetic properties in different coastal areas. The basic features of wind wave fields in different wind conditions are estimated. The structure of the wake patterns of fast ferries, the maximum and typical values of wake heights and their spatial variability are analysed. Waves caused by fast ferries generally are higher than those excited by hydrofoils or conventional ferries. Their daily maximum height typically exceeds 1 m and may reach in extreme cases 1.7-2.3 m at a depth of 5 mat the eastern coast of the bay. The highest wave components frequently have periods of 10-15 s. Waves with such properties do not occur in natural conditions in the area in question. The spatial variation of the average energy density of the ship waves and its flux is relatively small in Tallinn Bay. The daily average frequency spectra of ship-generated waves show that different parts of the coastal zone are affected by waves with largely different properties. [ABSTRACT FROM AUTHOR]