SPATIAL FORM OF THE CHAIN WHEN EXPOSED TO STREAM AND WIND ON THE SHIP RIDDEN AT SINGLE ANCHOR
Up to the present time the minimum required chain length during berthing of a vessel at single anchor rate-measurement is based on empirical formulas or model of a chain line lying in the centerline plane. The article shows that the flat catenary is obtained only when the collinear directions of wind and stream at least of one velocity is zero. If the wind and stream are at different angles, the chain will not lie in the centerline plane. Angles of drift and winds during berthing at single anchor are calculated for tanker type "Astrakhan". The similarity criterion of this problem is defined such as densities product of relations, projections of dead work and ship's bottom on the centerline plane, the square of speeds ratio. Projection forces of drag and lift force acting on the anchor chain in the spatial case are found. These forces significantly deviate from the coordinate axes. The non-dimensional form of threedimensional boundary value problem of the anchor chain equilibrium is obtained. The similarity criteria are: drift angle 0, the ratio of the weight of chain in water to the drag force Ф, the ratio of the coefficients of hydrodynamic drag chain for longitudinal and transverse flow. The boundary value problem is solved numerically in Mathcad. The smaller the value of Ф, the stronger form of chain will differ from a flat line.