Cruising

Chartplotter Protocols Page 3

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Don’t assume the plotter is correct. Several months ago, a driver who was dutifully obeying his car’s GPS made a right-hand turn—right onto some railroad tracks and in front of an oncoming train. He got out of the car in time, but the car was wrecked. While you could argue that he should have seen what was ahead of him, the incident is a great reminder that electronic devices shouldn’t be followed blindly. You need to use as many other navigational inputs as you can, including your eyes.

Plan ahead. You should always try to plan your passages in advance. Looking at both paper and electronic charts, selecting the waypoints, and then building your routes before you get under way is the best way to minimize the chance of making a plotting error.

I know there is a lot of discussion of whether it is necessary to carry paper charts if you have a chartplotter. Some commercial ships don’t have to carry paper charts, but their chartplotter displays are extremely large, similar in size to a conventional paper chart. Those ships also have a lot of equipment redundancy. Large plotters aren’t feasible for most recreational users, which means most of us are going to be using small chartplotters. Some of you may not agree, but I believe strongly that you could be vulnerable if you rely exclusively on just a small chartplotter. Personally, I won’t get under way unless I also have appropriate paper charts for the passage I am about to make.

Chartplotters have helped revolutionize some aspects of navigation, but navigational errors still occur and are sometimes the very tools that are intended to prevent them. Almost any problem can be minimized by having a solid understanding of the characteristics and the limitations of both GPS and chartplotters. You should also continue to use other electronic aids—a depth sounder, for example—and always keep up your other navigational skills: piloting, dead-reckoning, and, yes, using a paper chart.


Larchmont, New York-based Steven Henkind, M.D., Ph.D., is a marine-safety consultant who also teaches navigation.

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