A novel approach to tedious chart updatesJan 1, 2003
|From Ocean Navigator #115 |
As one who is on the water a lot, I too am concerned with efficient and reliable methods for keeping navigational charts up to date. I chuckle at the time, years ago, when I started sailing, of my intention to faithfully update my charts by subscribing to the USCG's Weekly Notices. As you may know, once on the mailing list, these weekly tomes poured in unabated as I promised myself to continue updating my charts. After a few weeks, they began to pile up on my desk, then got pushed aside by more urgent matters, then - well, you know the rest of that story.
That exercise convinced me of the practical futility of trying to update charts, and many mariners I spoke with came to a similar conclusion. But then I discovered the USCG's Light List, which includes details of essentially all the navigational aids in a given area. It occurred to me that my primary interest was knowing the identity, location, numbers, light characteristics, etc., about the nav aids, and that I could better and more efficiently accomplish this through the Light List rather than by trying to update the charts themselves.
The USCG Light Lists are published annually, so there still remained the problem of keeping them up to date. For this, I found that DMA (the Defense Mapping Agency) maintained a computer data base called NAVINFONET that I could directly access via telephone line from my computer (sorry, youngsters, this is pre-Internet). This database included all navigational aids, worldwide, for waters greater than 12 feet in depth, including US waters. Thus it covered both the USCG-maintained aids and those of foreign nations. Prior to sailing in an area, I would get the latest charts (out of date when purchased, of course), the current year's Light List, and the NAVINFONET download of the Light List updates. I was all set.
Now, the National Imagery and Mapping Agency (NIMA), the new DMA, has made this process vastly easier by putting all of the Light List information on the Internet. The U.S. publishes two types of light lists: One is the USCG Light List covering U.S. waters. The other is the NIMA List of Lights covering non-U.S. waters. When preparing for a cruise, you can download light lists from the Internet as follows:
1. Go to the NIMA web site at http://220.127.116.11/index/ and choose NIMA On-Line Navigation Publications.
2. This will bring up a link, NIMA On-Line Navigation Publications.
3. Notice the two options, either NIMA List of Lights or USCG Light List. First choose either the NIMA world icon or the USCG icon to determine which volume you need.
4. Next - for example if you are doing a cruise in U.S. waters - choose USCG Light List; this brings up http://18.104.22.168/pubs/USCGLL/pubs_j_uscgll_list.html, which gives the titles of USCG Light Lists by Volume Number and a description of areas covered.
5. For a Chesapeake Bay cruise you would choose Volume II; this brings up http://22.214.171.124/pubs/USCGLL/pubs_j_uscgll_sections.html?rid=3306. This is the cover page for Volume II, which offers a list of options. You can enter a navigational aid number or range of numbers, but for cruise planning it's easiest to choose Minimum Bounding Rectangle, which will give you aids within a geographic area defined by your choice of latitude and longitude.
6. This brings up http://126.96.36.199/pubs/USCGLL/pubs_j_uscgll_mbr.html* the Minimum Bounding Rectangle page, where you can specify the latitudes and longitudes and choose whether you want all or some aids within that rectangle.
7. For example, if you enter 3900N/7620W and 3858N/7626W and ask for All Aids from Volume II, you'll get a summary of search results indicating that four aids, No. 7840 through 7980, were located.
8. Click on the search link and you'll get the details of these four aids. Of course, if you specify a much larger area you'll get many pages of aids.
9. Similar procedures can be followed for the NIMA List of Lights for non-U.S. waters. And, you can specify larger geographic areas covering your entire cruise itinerary and alternate routes and ports. You can also specify the light ranges you are interested in; for example, you can ask for lights with ranges more than five miles, and it will filter out the lesser distances.
Even though we're rapidly moving toward all-electronic navigation, it's still essential in my mind to maintain and use paper charts and the NIMA Internet light lists make this practical.
Try it, you'll like it!Edit Module