Chart Navigation Secrets – How to Use Natural Ranges for Safer Navigation!

Did you know that you can use a navigation range to locate your exact position along any compass course? Now you can discover more secrets of this navigators friend.

Check you navigational chart for man-made ranges
Large harbors often have Coast Guard maintained ranges on each end of deep water channels to help ships keep lined up in the channels. Each range consists of a structure built on pilings with a dayboard on top. One range structure is built (or positioned) higher than the other.

Each range carries a rectangular or triangular-shaped dayboard with a central vertical stripe. As a ship or boat enters the channel, they line up the upper and lower dayboards to form an unbroken vertical line. This indicates that they are in the deepest, central part of the channel.

Know these nighttime range light patterns
At nighttime, some ranges show lights. The lower range carries a quick flashing light and the taller range an equal interval light (for example, three seconds of light followed by three seconds of darkness in a continuous sequence). Keep both lights stacked in a vertical line to stay in the center of the channel.

How long can you steer on a range?
Navigational charts with Coast Guard ranges show a solid line in the middle of the channel. This tells you it’s safe to continue to use the range. Near the end of the channel, it turns into a dashed line. At this point, you will have a turn coming up, so you must find another range to use.

Expect deep draft ships to use the center of the channel to stay on range. Rule 9 of the Navigation Rules states, “A vessel of less than 20 meters in length or a sailing vessel shall not impede the passage of a vessel that can safely navigate only within a narrow channel or fairway.” If large ships are present, stay to the right of the channel center for safety.

Look for natural ranges
If Coast Guard maintained ranges aren’t present, look for natural ranges that line up with your compass course. A piling and the edge of a roof, a church spire and a radio tower or the left side of an island and a buoy. Highlight charted natural ranges along your course. Indicate that point along the track where you must stop using the range (as described above).

Use these steps to stay on range
Wind, seas and current can combine to make steering on a range a challenge. Use these tips to regain range when these natural forces push you off your trackline:

Ranges ahead of your bow

1. Concentrate on the lower range.
2. Lower range to the left? Steer left to get back onto the range-line.
3. Lower range to the right? Steer right to get back onto the range-line.

Ranges astern of you

1. Concentrate on the higher range.
2. Higher range to the left? Steer left to get back onto the range-line.
3. Higher range to the right? Steer right to get back onto the range-line.

Now you know the secrets of how a chart navigation range keeps you in the channel for safety and security. Keep your small cruising boat on her compass course the fast and easy way–with man-made or natural ranges.