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Several aspects of digital navigation can enhance what’s available with traditional map and compass. One problem with large maps is the difficulty of determining latitude and longitude when the map is folded into a usable size. This problem is partially solved by printing the digital map to a usable scale and size. Also, viewing software can print latitude and longitude or UTM grid lines on any map. This makes pinpointing locations on a map much easier when used with a GPS.
Charts have compass roses on them, which show the direction of magnetic and true north. This allows for simple map and compass work in the field. However, roses may not be printed near the portion of the chart where you’re paddling, and they aren’t printed on maps at all. Because charts and maps often don’t have readily visible north-south lines (especially over the water), I often draw vertical lines on paper charts and maps to make it easier to align a hand compass due north. Some people prefer to draw angled lines on the map or chart corresponding with magnetic due north.
Once a chart or map has been created as a digital image, manual aids to field navigation can be placed on the chart or map electronically using practically any software that can read standard graphics files and draw lines and circles. Photo-editing software, CAD applications or even some word-processing programs can be used to add compass roses, true-north lines and magnetic north lines. You also can rotate the digital map image, which might be useful if you’re paddling in a fjord or along a coastline. Rotate and crop the map image so that the fjord or coastline is aligned with the long axis of your paper to maximize the useful information on the page. (Refer again to Illustration 1. This map file includes examples of magnetic north and true-north lines, a compass rose, waypoints, annotations, latitude and longitude, etc., all of which have been added to the map file digitally.)
Has anyone ever said, “Let’s paddle to Perry Island next week,” you said “Great,” and thought “Where the heck is that?!” The Geographic Names Information System will solve your problem. This collaboration between the USGS and the U.S. Board of Geographic Names is a database of over two million physical and cultural geographic features in the United States, by name and location. If I type “Perry Island” into a map-viewer program, it’ll search the database, identify every map or chart on my computer that contains Perry Island, and display Perry Island on a map or chart on my computer screen. So that’s where it is! The Geographic Names Information System is also available on the Internet, and once the feature is located, it provides links to view and download the appropriate DRG.
One interesting feature of using raster maps is that virtually any paper map can become digital. Scan a map into the computer as a graphic image. Using a viewer program, designate the method used to “project” or draw the map in two dimensions and the “datum” used by the map to describe the shape of the world. Finally, define the location of a few points on the scanned map image by latitude and longitude or UTM coordinates. These points can be based on known locations, such as benchmarks or GPS readings. The viewer software then uses complicated formulae to georeference the map. At that point, the scanned and georeferenced map can be just as useful and accurate as a digital map purchased from a digital map supplier.
Why go to this bother? You may own several paper maps that you’d like to utilize rather than buying new digital maps. You may find that no digital map is commercially available for your area of interest. You may have a paper map of an area that’s too specialized to warrant commercial digital distribution, such as a map published by a local birding organization showing special information about shorebird nests and migration routes. You may want to navigate using recent aerial or satellite photographs of an area rather than an outdated digital map. Most digital charts and maps are based on paper charts and maps and are thus no more accurate than their paper ancestors, which may be based on decades-old data. In areas with relatively rapid geological or geographical change, using a georeferenced aerial or satellite photograph as a map may be a very useful navigation tool.
In many viewers, you can attach other files to waypoints or other features. If you want to remember what your camping beaches looked like, just take a photograph of each camp and attach it to the waypoint for each beach. In the viewer, you can click on that waypoint and display the photograph. Other possible attachments could include a tide table, the view from the beach, a daily diary or recorded sounds.
Kayak navigation has evolved substantially over the past few years. The availability of digitized charts and maps, relatively inexpensive and powerful personal computers, and high-quality applications has led to substantial development and growth of digital navigation. As with many technological innovations, technology filters down. Digital navigation resources that once were available and were essential only for commercial shipping are now available to assist and enhance even paddle-powered kayakers. I’ve found that with some effort, digital navigation can support, enhance and expand traditional navigation resources. I don’t expect to throw away my map and compass, but with digital navigation, I can do much more.
To access a sidebar containing the Internet URLs for the plethora of resources described in this article, click here.
Bob Hume is a lawyer practicing in Anchorage, Alaska. Since the mid-1990s, he’s paddled extensively in Prince William Sound and throughout south-central Alaska. Despite the tone of his article, Bob states that he is not a computer geek. He’s been using and learning about digital navigation for around five years.
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