The term “set and drift” is used to describe external forces that affect a boat and keep it from following an intended course.
The movement of water is impacted by: meteorological effects, wind, temperature differences, gravity, and on occasion earthquakes.
A mariner needs to be able to steer the ship and compensate for the effects of set and drift upon their vessel while underway.
The Course Made Good is the direction in which a ship or vessel has traveled with the effects of current, wind, and helmsmanship.
Set and Drift can be calculated by using a vector diagram and can be drawn and measured on a chart, maneuvering board or even a plain piece of paper.
A compass can measure and draw arc and circles on charts and maneuvering boards.