Nautical Charts: How-to
How to read nautical chart index images
When referring to nautical chart indexes in the Nautical Chart book, the boxes on top of the regional map have several numeric references.
The italic numbers are for sailing direction limits, the boxes for this have dashed lines. These numbers also appear within an oval.
The italic numbers within a boldly outlined box are for planning guides of sailing directions.
The next type of number you will see in images such as Region 1 (below) are dashed, for example 1-3. This type of number refers to the next series of maps in the regional sections. The 1-3 represents Figure 1-3, the third detailed map of region one (Figure 1-3 is reproduced farther down on this page). If this was an index of Region 4, the image would have references to other more detailed maps such as Figure 4-5., the fifth detailed map of region 4.
The first step in locating nautical charts is to identify your region. This can be done using the regional index on the first page of the Nautical Chart Catalog.
The Regional Nautical Chart Index can also be found on the first page of the Map Library's Current Nautical Chart Page.
After you found the specific region you may need, then you can proceed to the Figure which will contain your Nautical Chart Numbers, such as Figure 1-3 below. In these chart indexes labeled Figure x-x, or in this case Figure 1-3, you will find more boxed areas, with a different number system. The main focus of these maps is to provide a visual reference for nautical charts and their corresponding numbers, which are usually found in one of the corners of the surrounding box.
So for a Nautical Chart of Cape Dissapointment, you would look for Chart number 18003. If you wanted to see if this same chart was at the University of Oregon, Map Library, you would refer to one or all of our lists: Current, Historical and/or Superceded Nautical Charts.
In Figure 1-3 you will also see that major points of reference are mapped, such as cities or in this case the Strait of Juan de Fuca.