These differences in the accuracy of your position and your chart also underscore a common mistake when setting up waypoints and routes. Never place a waypoint too close to a charted navigation aid. The aid you see on your screen may not be exactly where you think it is.

USING ELECTRONIC CHARTS

So, how do you use electronic charts? In order for navigation software to display charts, you must tell it where the files are located. This task is called loading the chart and is separate from downloading the files and copying the charts to your hard drive. Charting applications typically use one of two systems for locating and recognizing charts: a smart folder system or a directory system.

Smart folder applications, such as Coastal Explorer or GPSNavX, have a designated folder on your hard drive. Any chart dropped into this folder is identified as a new chart. Each time you start the application, it scans that special folder, says, "Aha, those are the charts I have," and loads those charts as its database.

Directory-based applications, such as Marine ENC or MacENC, build a directory of charts and chart folders. You can have multiple charts in multiple folders, but you need to actively tell your software where those charts are located. Every application accomplishes this differently, and the process is usually described in detail in the application's manual or help files. The terminology varies, but the idea is the same: after the first set of charts that came with your software, you must direct it to the location of new chart files.

Smart folder applications are easier to manage, but they are not a panacea. Because everything is automated, they have a lot less flexibility and can cause problems.

A common problem with smart folders is the temptation to get sloppy with file hygiene. Becoming a "chart collector" and indiscriminately dropping chart files into this folder will severely bog down your laptop's performance. Furthermore, since every chart must first be read into the directory, a hefty smart folder will make your application significantly slower to open.

Directory-based applications require some attention to the manufacturer's operating instructions, but they are a precise chart management system that allows you to load and unload charts or regions as you need them. A little bit of time invested in learning your charting application's process will stop directory clutter and maintain optimal laptop performance.

Even if your laptop is a screaming demon, you should only load charts that you need. Selectively pre-load and unload regions as you travel. We have literally thousands of charts on our laptop, but rarely need access to more than a few hundred at a time.

Finally, although NOAA continually posts updated charts, these are targeted primarily for commercial vessels, which are required by law to carry the latest chart edition. Most recreational boaters are comfortable updating their entire chart catalog once a year or before a major cruise to a certain location.

NEXT WEEK: A Review of Free Navigation Software