  We applied canonical transformation to water wave equation not only to remove
cubic nonlinear terms but to simplify drastically fourth order terms in
Hamiltonian. This transformation explicitly uses the fact of vanishing exact
four waves interaction for water gravity waves for 2D potential fluid. After
the transformation well-known but cumbersome Zakharov equation is drastically
simplified and can be written in X-space in compact way. This new equation is
very suitable as for analytic study as for numerical simulation. Localized in
space breather-type solution was found. Numerical simulation of collision of
two such breathers strongly supports hypothesis of integrability of 2-D free
surface hydrodynamics.
