  Turbulent ship wake conservation at a long distance is one of unsolved
problems at present. It is well known that wakes have a rotational structure
and slowly expand with distance. Nevertheless, experimental data on their
structure and properties are not sufficient. On the other hand, these
experimental data show that the divergence of wakes does not change according
to the law 1/5, as predicted by the theory. In our work we study the effect of
helicity on the parameters of a turbulent ship wake. Taking into account the
helical nature of the wake, we can clarify the difference between turbulence
inside and outside of the wake on the one hand, and slow its expansion with
time.
