img9029In today's marine environment, a GPS or a global positioning system receiver is the navigation instrument of choice. For GPS equipped sailors, a simple push of a button will determine exact longitude and latitude. Plotting the intersection of these coordinates on a navigational chart illustrates the boat's position. But what happens when the batteries fail or when your hand-held is dropped on the cockpit floor? Knowing some basic navigation skills can get you where you want to go without the use a GPS receiver.

The basic ideas relating to coastal navigation are fairly simple. If you are close enough to a navigational buoy or marker, simply reading the number on the object then referencing the chart will give your exact location. Of course if the object is a channel marker, just be sure you know which channel you're in.

If the navigational aid is off in the distance, you will need to take a bearing. If your supply of navigational equipment does not yet include a hand-bearing compass, simply steer the bow towards the object and record the compass heading. This is your bearing to the object. Now take your chart and with the parallel rules, find the compass rose and hold one side of the rules on the bearing you have noted. Then, walk the rules to your chosen object. Draw a line from the object out along this magnetic bearing. This is called a "line of position" (LOP). Great, now you know you are along this line at some point. But where?

Next, you will need to find another object to take a second bearing. The closer this object is to being 90 degrees off your first object the better. If the angle is too small or too large, the margin of error increases. Once you have the bearing on your second object, again, mark it on the chart. Where your two lines of position cross is your current position. There you are!

Keep in mind, the objects you use for your fixes don't necessarily need to be navigational aids. In fact, a large radio tower or hill noted on the chart can be seen from a much further distance. Charts will not only note hills and towers, but along a coastline, you will also note items such as "tallest building" or "smoke stack".

If you're sailing along a coastline and can only identify one object for a bearing, another cross-reference line can be found by using your indicated depth. Use this depth, correspond it to the matching depth line along the coast for your second reference line. Also, lining up two points of land can give you a line of position (LOP).

Another important aspect of navigation relates to "Set and Drift". It is important to remember that just because your compass reads 90 degrees your boat may not actually be "tracking" 90 degrees.

img9028Whether you are sailing close to or off the wind, a sailboat hardly ever sails on the course it is pointing. The keel or centerboard helps. But the boat is usually "sliding" downwind somewhat (called "making leeway"). Similarly, current and wind conditions can have the same effect. Depending on conditions, a vessel sailing toward the wind is usually moving 5 to 10 degrees off its noted compass course. With current added, it can be much more.

Taking some time to practice these skills prior to needing them will insure the accurate location of your vessel. Knowing that you can determine your location at any given time not only adds to your safety at sea but adds to your enjoyment on the water as your skills increase.

Steve Colgate is the founder of Colgate Sailing Schools, with locations in Tortola BVI, Captiva Island FL, Duck Key FL, St. Petersburg FL, Chelsea Piers NY, Liberty Landing NJU and Newport RI.

Offshore Sailing Schools
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Fort Myers, Florida 33908
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239-454-1700
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