tides, currents, and leeway 115
boat moving at expected speed?
boat moving faster than expected?
boat moving slower than expected?Current has affected our boat to create two out of the six boat/TR relation-
ships: It is to the left of the TR and moving faster than expected.
Extend the TR and check for dangers ahead. Now that you know the eff ect
of the current, predict your track by extending the COG line 1 hour or more
ahead of your most recent fi x. Check for dangers on all sides of the extended
COG line; then plot the safest course to keep you out of danger. Once we know
set and drift , we can quickly and accurately calculate the course to steer to keep
us in safe water. Note: this assumes a steady set and drift of current. If you expect
the current set or drift to change as the stage of tide changes or as you leave one
channel and enter another, you’ll want to accommodate the expected change in
your calculations. When visibility is poor and the eff ects of current are signifi cant,
run short courses between prominent navaids or landmarks.
How to Cross the Gulf Stream or Any Other Ocean Current
Solve any current problem by building a course-to-steer, or CTS, triangle. A CTS
triangle has three sides, called vectors. All vectors represent a specifi c direction
and speed.
Once we extend our COG (top), we see that our course is leading us toward a dangerous
shoal. We must plot a new course (bottom) that will take us safely to our destination.