Definition
Speed made good is the length of the ground track divided by the elapsed time, differing from speed through the water by the along-track component of the tidal stream. A yacht logging 5 knots with a 1.5 knot fair stream makes good 6.5 knots; against it, 3.5 knots. Over a passage with a turning stream the net effect may be small, which is why an average is taken over the whole leg rather than instantaneously.
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