Upstream Vessel

An upstream vessel is one proceeding against the current, heading toward the source of a river or the flood in a tidal channel; it stems the stream rather than running with it. In river and estuary navigation the upstream (stemming) vessel has better steerage and stopping control because water flows past its rudder, so it normally gives way and waits while the downstream vessel, carried by the current and slower to stop, holds its line. Many inland and port rules give the downstream vessel priority and the right to nominate the passing side for this reason.