How to Compensate for Current While Steering

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Most people compensate for current just "by eye," which is fine if the current is very small compared to your speed. But if the current is fast, you need precise control or it is going to be acting on you for a long time, it can help to take a few moments to estimate the direction you must steer.

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Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

The current direction and speed
Pencil
Paper
Divider (2 sharp points)
Parallel ruler

Plotting the Current Triangle

Step1

Align the parallel ruler with the direction of the current from the center of the compass rose.

Step2

Walk the parallel ruler to a convenient empty part of the chart and draw a line.

Step3

Set the dividers to the distance the current will travel in 1 hour.

Step4

Using the divider along the current line, mark the 2 points. Put an arrow head at the end in the direction of the current. Mark the other point as
"2."

Step5

Set the parallel ruler to the direction you wish to travel from the center of the compass rose.

Step6

Walk the parallel ruler to the current line so that one edge goes through the tip of the arrow head. Draw a line through this point, putting an arrow head in the direction you wish to travel with the point connected to the point of the current arrow.

Step7

Set the divider to the speed you wish to make over ground then lay this distance from the arrow head along the line of travel away from the arrow head. Mark this point as "1."

Step8

Using the parallel rules, draw a line from point 1 to point 2. The length of this line is the speed you should be driving the boat and the direction is the TRUE direction you should be steering.

Tips & Warnings

Special pads are available for plotting this off the chart.
Draw lightly so you can erase the lines when you're done.
Never completely trust a solution like this. Keep your eyes open and watch because a current may be different than you expect, it might be changing or you may introduce a virtual current through poor steering or instrument calibration.