NOAA Electronic Charts


NOAA electronic charts

Review by Jimmy Havok

Recently, I looked over the navigational charts available for my area, and was disappointed to find that the area of most interest to me was only available on a large island-wide map, without the kind of scale I wanted. Disappointed, I decided to look around the Web to see if there were any electronic charts available.

It turns out that the National Oceanic and Atmospheric Administration, Office of Coast Survey has a pilot project to distribute navigational charts in electronic form. It is currently in the beta stage, with a fairly wide but incomplete set of about 100 charts available, and by good luck, my own area is covered. The OCS distributes the charts as .zip files through a very nice download management page, where you can check off the different charts you are interested in, and then they are all bundled together as one download. If you have a fast and dependable connection, just check everything you are interested in, but if you are on dialup, it might be better to download each chart seperately, since some are rather large. The charts are distributed with the warning that they are not to be used for navigation.

The charts are in a format called Electronic Navigational Charts (ENC), which can be read by several different free programs. The NOAA has a page that links up to the various sources for the viewers. Two of them work with Windows 95/98. The other three need Windows 2000 or XP, so I was unable to evaluate them. We'd be interested in seeing a review of the Win2K/XP viewers, if anyone out there would write them up. (Editors Note: I was able to download and use both programs on an XP machine with no problems.)

The Win98 ENC viewers are called SeeMyDENC, distributed by SevenCs GmbH, and dKart Look, distributed by HydroSERVICE. dKart Look 4.0 is supposed to be a Win2K program, but except for the print feature, it worked well on my Win98 machine. Both installs were easy and quick on my machine.


SeeMyDENC handles SENC, S-57 and DENC files. The NOAA files are in the S-57 format.

It took some time to open the large map of Oahu I was interested in, as SeeMyDENC spends a lot of time checking the file for problems, but eventually, it did open and the level of detail was amazing, with a zoom feature that allows you to zoom in as deeply as you want.

SeeMyDENC Screen Shot (click to enlarge)

The display can be customized to an incredible degree, ranging from a simple outline of land masses, a few depth contours, and some standard navigational features, to full labelling of all features along with with soundings and a latitude/longitude grid, with so much information the map is almost unreadable, and with two choices of symbols, simplified and traditional. This is where I encountered my first problem with SeeMyDENC: there was no reference to explain the meanings of the symbols, though the HTML help file did note that the symbols used were "according to the IMO Draft Performance Standards as well as a set of standard symbols that were designed according to the International Chart 1," so it shouldn't be too difficult to round up an outside reference.

Moving around the map is quick and easy, simply put the cursor at the point where you would like the map to be centered, hold down the "shift" key, and left click. Then use the zoom buttons until you are as close as you want to get.

My favorite feature was the notes. Simply left click on any point on the map, and a set of notes covering navigational warnings, names of features, soundings and navigational position. For instance, I clicked on a group of rocks a few hundred yards offshore:

SeeMyDENC Report

The program will print out your active window, however, the page setup is not very good, so maps printed out on 8.5x11 are too small to be practical. There is a work-around, though, since SeeMyDENC will save any map to the clipboard so it can be imported into an outside graphics program, where it can be sized, cropped, and printed to suit your needs. You should also be able to take the file down to a local print shop and get it printed out in a larger format. Remember, though, the charts are not meant to be a substitute for official navigational charts.

SeeMyDENC has one very serious usability issue.. The charts don't have a scale or a compass rose on them, so the only way to figure distances is by using a known distance within the map to estimate. Headings are easier, since the latitude/longitude grid will give you your true bearings. You'll have to figure magnetic deviation yourself. The omission of those features may be intentional, though, since the NOAA repeatedly states that these charts are not meant for navigation.

dKart Look

dKart Look opened the map file more quickly. Version 3.0 was much more readable than SeeMyDENC, due to some good choices in screen colors, but Version 4.0 has an irritating overlay of ovals. However, Version 4.o also has a great tool, Measurement, under the Files menu, that shows the distance and bearing between any two points, simply click on one point then move the cursor to any other point and the distance and bearing are displayed.

dKart Look V3.0

Other than that, both versions of dKart Look are quite a bit simpler than SeeMyDENC, and lack a few of that program's useful features. V3.0 (above) did not have a print feature. However, that problem can be worked around easily using Windows shortcut keys, Shift-Print Screen will save the current screen to the clipboard where it can then be pasted into an outside graphics program. V4.0's (below) print features were better than those of SeeMyDENC (except for the previously mentioned ovals), but apparently were incompatible with Win98, since they caused Look to crash on my machine.

dKart Look V4.0

Navigating around in dKart Look was simple, just left-click, and that point becomes the new center of the display, then zoom in or out using the toolbar buttons.

What was most notable thing missing in both versions was the lack of landmark names. Some of them could be retrieved by right-clicking on the area of interest, but there were many where names that showed in SeeMyDENC could not be seen in dKart Look. One area where dKart was definitely superior was in the formatting of the notes. Both programs pop up a window with navigational notes when you right-click an area, but the formatting of dKart Look was much more readable, with less redundancy and garbage characters.

dKart Look Report

The View menu allows you to choose layers of data, to customize the map to whatever degree you find useful, allowing you to choose whether or not to display items like constructions, soundings, navigational aids or special areas.

These electronic charts are a great companion for the simpler non-mapping GPS units, since you can pull lattitude and longitude of waypoints off the charts in both viewers simply by moving the cursor over the chart.

Despite the warnings that these charts are not to be used for navigation, you can learn a lot about your local cruising grounds from them, and can print out details to supplement your official charts, especially if the area you are interested in is not commercially navigated and low-scale maps aren't available. For instance, I learned that there were several bouys a few miles off-shore of the launch ramp I use, so now I have a voyage out to see them on my list of adventures, and thanks to dKart Look, I have both the compass heading and an accurate distance to work with.