NAVIGATION
Navigation is broken down into two categories-celestial navigation and piloting. The former is navigation based on the position of the celestial bodies and is normally used out of sight of land. For navigation on bareboat cruises, we use piloting which is navigation by reference to landmarks, buoys, sounding and the like.

PILOTING
Coastwise navigation or "piloting" consists of transferring your actual position to an easily readable picture in the form of a chart. Basically it requires that you determine your position (called a "fix"), locate the fix on the chart and then use the rest of the chart to answer certain questions. The fix has answered the question "Where am I?", but an even more appropriate late question would be "Am I in safe water?". In other words, is there enough depth of water for the boat's draft, where are the nearest dangers to the boat such as rocks, reefs, shoals and riptides. From the chart you want to be able to determine a course or courses to steer that will allow a safe passage to deep water or to some other destination.

THE CHART
The chart is a neat "road map" of the sea printed by the u.s.
Department of Commerce and available at many nautical supply stores. The area a chart covers and the identifying number is listed in the nautical chart catalog. Figure 63 shows a section of this catalog. If sailing the western end of Long Island Sound, for instance, look at the catalog sheet and note that chart #12354 is needed (the circled number in figure 63).

For very small boats, the Small Craft Series of charts is handy because they are prefolded compactly and don't need a large, flat surface to spread on. Also, one chart covers the same area that a number of the other charts cover, so they are more economical to purchase. The only problem with the Small Craft Series of charts is they don't give you the "big picture" of the area and it's often difficult to find the next adjoining chart when you run off the edge of the first. The less distinct outline with numbers such as "12372" in figure 63 show the coverage of Small Craft charts.

As can be seen in the catalog, charts come in different scales.
They are all roughly the same physical size, but cover different sized areas. Chart #12375, for instance, covers only a small portion of chart #12354, yet blows it up to about the same size as #12354. Since #12375 enlarges a small area, it is called a "large scale" chart. Such charts are used for entering harbors where precision and accuracy is more necessary than when in open water. If you're planning a trip, a smaller scale chart covers more distance and is easier to use.

Though charts have many different scales, the most common are 1 :80,000, 1 :40,000, and 1 :20,000. This means one foot on a 1 to 80,000 chart is equivalent to 80,000 feet on land or roughly 13 nautical miles.

On a 1 to 20,000 chart, one foot equals 20,000 feet or about 3.3 NM. Obviously there will be less detail when you crowd 13 miles into a foot of chart space than with 3.3 miles, so the latter is a large scale chart which shows more detail. The smaller the numbers, the larger the scale and vice versa.

The traditional equipment used are still parallel rulers and dividers. The former moves a course or bearing on the chart from the compass rose to your position or that of a landmark you sighted. Dividers measure distance. Though those two items and a pencil are all one needs, others have been developed that some sailors find helpful to use. If you cruise on a charterboat in Europe, you are not apt to find parallel rulers as part of the boat's navigation equipment. Instead there will be some form of protractor, a clear plastic rectangle with a compass rose in the middle. Lay one edge on the desired course and slide the center of the protracter over a meridian of longitude. The reading on the compass rose will be your true course as in figure 64. In this case the course between the bell and whistle buoy is 071 degrees or 251 degrees depending on which direction you are sailing. Remember to correct for variation.

 

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