Tides and currents — predictions and corrections

Bowditch Ch. 23 §2302

Bowditch Ch. 23 §2302 — Navigational Errors Set and drift describe the effect of current on the vessel's track. Set is the direction toward which the current is flowing; drift is the speed of the current. The vector sum of the intended course (course made good through water) and the current vector gives the actual course over ground.

Bowditch Ch. 24 §2401

Bowditch Ch. 24 §2401 — Currents Surface ocean currents are driven primarily by wind, with major gyres in each ocean basin. Tidal currents are driven by tide rather than wind and reverse direction with the tide.

Bowditch Ch. 24 §2402

Bowditch Ch. 24 §2402 — Currents The vector triangle for current correction is: course steered + drift vector = course made good. Inverting it: from course made good and drift, derive the course steered required to make a given track over ground.

Bowditch Ch. 9 §901

Bowditch Ch. 9 §901 — Tides and Tidal Currents Tides are the periodic vertical rise and fall of the sea level due to the gravitational interaction of the moon, sun, and earth. The principal lunar tide has a period of approximately 12 hours 25 minutes.

Bowditch Ch. 9 §902

Bowditch Ch. 9 §902 — Tides and Tidal Currents Spring tides occur near new and full moon and have the greatest range. Neap tides occur near first and last quarter moon and have the smallest range.

Bowditch Ch. 9 §903

Bowditch Ch. 9 §903 — Tides and Tidal Currents Tidal currents are the horizontal flow of water associated with the rise and fall of the tide. Flood is incoming, ebb is outgoing, slack water is the brief period of zero flow at the turn.