Safe Navigation Starts with Accurate Charts

12327_lowrescroppedThe 2016 TrawlerFest boatshow and seminar series recently wrapped up in Bay Bridge, Maryland. For those who missed it, Bob Sweet presented a mini-course style seminar focused on helping recreational mariners—whether inexperienced or “old salts”—confidently plan and safely navigate while on the water.

Sweet breaks down the navigation process into three distinct phases, as follows:

  • PHASE 1 – Plan: Pre-check safe paths
  • PHASE 2 – Navigate: Follow pre-checked paths
  • PHASE 3 – Check: Verify where you think you are


Key Takeaways

In his mini-course, Sweet walks through each phase of the navigation process, providing useful tips, clear examples, and helpful formulas. He offers a wealth of information. In the end, he offers this reminder:

Remember above all else even when everything else fails, there are three tools that won’t let you down: 1) your eyes and other senses, 2) your compass, and 3) your paper charts. It pays to know how to use them.

In this blog, we’ll take a high-level look at Sweet’s advice on how and when to use paper charts.


The Importance of Paper Charts


Sweet recommends using paper charts for planning because of their wide view and detailed information. He explains that added information on printed charts, which does not appear on digital charts, is critical when determining and prequalifying safe paths to navigate.

When you are planning a leg to navigate on the water, you are pre-qualifying that leg to be clear of various fixed dangers, both above and below the surface of the water.

Charts use a variety of symbols and notations to alert you to depths, bottom type, and hazards.

When prequalifying your paths, you should always use the most up-to-date charts available.



Recall that your job during the navigation phase is to carefully follow the paths you prequalified during the planning phase. For navigating, Sweet says digital charts are a good choice.

The chart details are less of an issue while navigating as long as you stay on the prequalified paths.

GPS (rather than a chart) is the main tool for navigation.

While underway, your GPS receiver determines your position with a high degree of precision based on the signals it receives from satellites. Your receiver then computes position, direction and speed over ground, and bearing and distance to waypoints you store and select in your GPS.



Be warned! Even though you’ll be using GPS and digital charts during navigation, you still need to verify that you really are where you need to be.

This phase is critical. You must verify your position, using a combination of your eyes, independent sensors such as radar—and paper charts.

Your GPS is accurate but not infallible. Not only that, you could have incorrectly entered some of the information into your GPS. It’s just a machine doing what you tell it to do… assuming that it is working properly. Just about every seasoned boater has had an experience with a misbehaving or suspect GPS at least once. Checking says you use your eyes and other resources to make sure you are where you think you are.


Sweet offers the following rule of thumb: 

You should be able to put your finger on your present location on a paper chart within 10 seconds at any time. This says two things. One, you have charts and they are close by. And two, you have been keeping track of your location and checking it.


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