Tidal stream atlas

A tidal stream atlas is the Admiralty NP-series publication that shows the set and rate of the tidal stream over an area by a sequence of charts, one for each hour before and after high water at a standard port. Each chartlet uses arrows for the stream direction and figures for the rate in tenths of a knot at neaps and springs, so the navigator reads off the expected set and drift for any state of tide. It complements the tidal diamonds printed on the chart by showing the whole field of streams as it turns through the cycle. The navigator uses it to carry a fair tide, plan a tidal gate, and compute the course to steer.