Seven Tips for Effectively Highlighting Your Navigational Charts

With chart in hand and a boat ready to hit the water, it pays to take the time to “highlight and annotate” your chart, says John Jamieson in a recent post on “Sailing navigation begins with the process of interpreting what you see and how that will affect your sailing boat and her crew now and in the future,” writes Jamieson as he outlines seven effective manners in which you can mark your navigational chart. “You will keep sailing safer when you make the most of your navigation preparations dockside before you cast off that first line.”

The following annotations are suggested to ensure safer, easier navigation:

  1. Mark shoals and set the alarm: Jamieson recommends you mark any shoal within two miles of your course. At the same time, a depth sounder alarm should asset to alert a sailor when a boat drifts within a mile of these shoals, thus giving time to change course.
  2. Look for ranges (transits) for ‘bulls-eye’ navigation: When evaluating your chart, you should look for two charted objects that line up with the channel. This will enable you to stay in the center of the channel.
  3. Scan for wrecks that could cause you harm: Knowing that wrecks can shift position, mark wrecks that you will encounter, all while remaining vigilant to ensure you do not sustain damage to your boat.
  4. Circle emergency anchorages to stand out: According to Jamieson, losing engine power in a narrow channel will force you to move your boat off-course. By marking the emergency anchorages, you will know where to go…safely.
  5. Darken latitude and longitude scales to ease eye strain: So the scales will stand out in low-light situations, Jamieson suggests you darken them on the right, left, top, and bottom of the nautical chart.
  6. Make a customized distance scale for faster plotting: Make your own distance scales for each of the most common chart scales you use aboard. Using a laundry marker for visibility, draw a vertical or horizontal line and mark off miles and tenths.
  7. Form a “box of protection” around your sailing courses: With an eye toward avoiding rocks, wrecks, and obstructions, Jamieson recommends you form an imaginary rectangular box around your sailing track. Each side lies about two to three miles away from any point of the sailing track. Highlight any features that may require your attention or that of your crew.

Effective use of navigational charts is an important component of a safe and enjoyable boating trip. Jamieson’s tips offer you clear, concise ways to add value to your charts — and ensure they are effectively tailored to the unique needs of your trip.

To read more about this subject, visit John Jamieson’s column at To learn more no-nonsense cruising skills, visit Jamieson’s website at


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