How to Read Nautical Charts – 3 Easy Tips for Better Clarity

Many of us receive the call for exploration from those inner chords in our gut.  Like a thirst that can’t be quenched, we are always seeking new ways to discover the world around us.

No method of travel offers as much freedom as one can attain on a boat.  Once you are out at sea, you are limited by only your imagination for where to go.  But although you might receive the call of the ocean, becoming proficient in navigating your way around it might seem overwhelming at the start.

Reading charts is the best way to become acquainted with the ways of the sea.  In today’s day and age, many rely on GPS and other high-tech instruments to locate themselves, find out their heading, and make sure they are still on course.  But this technology is still very new compared to how long people have been at sea.  For hundreds, even thousands, of years, people have found their direction (charted their course) using no more than a chart, compass, straight edge, and a passion to explore.

A map is what you use on land to find out where you are going.  At sea, we use a chart.  There are a few differences between reading a map and reading a chart that will help you become a more seaworthy navigator.  Let’s take a look at those now:

Understanding Bearings 
Everyone has heard the term “Get your bearings”, but few know that is a nautical term.  A bearing is simply a line between two points.  When you see two points from sea, generally a headland or other distinguishable landmark, the next step is to find your “heading” – direction on the compass toward that object.  from there you can draw a line on the map through that point using the respected angle you found.  Using two points will set your bearing, which is a line between the two headings on which your boat somewhere lies.

Using three points, finding their bearing, and drawing a line, will produce a Fix, or a single point from the three lines drawn.  This is how mariners can determine their exact point on a chart.

Depths
These are the numbers that seem randomly interspersed throughout the water.  This is very important as it can help identify points to avoid, and also to help predict sudden changes in sea conditions.  With your newfound knowledge of acquiring a fix, you can find where on the chart you are, and determine whether you are safe or in danger.

Lighthouse Clues
You may or may not know that each lighthouse has it’s own method of flashing that helps people at sea identify which lighthouse they are actually looking at.  On a chart, a lighthouse is designated by the simple abbreviation “LH”  Knowing the lingo will help you determine where you are.   The following chart helps determine what type of light sequence it emits.  On the chart will be a period, or for how long the light is flashing.  For example:  F 10s stands for “fixed, 10 seconds”.  So a solid light will stay lit for 10 seconds.  See the chart above for a key to what they mean.

These quick tips are only a brief overview intended to help bring clarity to a piece of information that many are unaware on how to read.  Once you decipher the clues, you’ll find that reading a chart is as easy as reading a map.  From there, you are on the first step toward navigating our great big seas!  Remember to never outstep your knowledge boundary, and for the best results, please take a course from a seaworthy captain.  Yarr!

 

For more information:  The wikipedia page on Nautical Charts has everything you need to decipher the chart.  http://en.wikipedia.org/wiki/Nautical_chart

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