Sunday, July 3, 2016

Light Lists—A Modern Look

The Light List (LL) is a crucial USCG publication for navigation for several reasons. The primary one is it includes information about the aids to navigation (ATONs, ie buoys, lights, day marks, radio aids) that is often not available on nautical charts, such as the nominal range and height of some lights, and other descriptions. This is especially true when relying on paper charts or using echarts in the RNC format, which are just graphic images of the paper charts.

Cover of the US Light List

A partial exception comes into play when using official US vector echarts (ENC) as these charts do include ATON data that are updated when the charts are updated, so in principle with automated ENC updates, you have all the latest ATON information as of about 10 days. They are updated every week, with about a 3 day processing time.  Thus an updated US ENC is much like having the latest Light List on board—but we are then at the mercy of our echart program that we count on to alert us that a new edition is available. 

But even with updated ENC, we should at least download one copy of the LL so we get all the extensive support tables and information that appears in the front part of the book.  We have long held that your best lesson on lights is to just read the 25 or so introductory pages to an US LL, including especially the Preface and Glossary included. There are also many helpful illustrations on these pages.  So the second important reason to have a LL is to learn how to interpret the lights, buoys, and other aids we run across on the waterway.  The LL is especially value for interpreting daymarks and it is growing increasingly important to understanding AIS aids. Those using USCG DGPS will also find crucial data there

But the point of this note is not the value of the LL, but how to get it onto the boat or your phone, and to keep it up to date.  The printed version is the same as it has been for years. Namely, once a year they publish an annual edition that is updated as of week 52 of the previous year.  The US government no longer prints these, but private companies have picked it up and do so.  They sell for about $53. The Canadian counterparts cost $30 printed, and the British Admiralty versions cost about $68. Both US and Canadian books are available as free pdf downloads, but not the Admiralty products.

We have then these options for getting the US LL into our computers or phones:

(1) US annual editions 

The point to stress here is this link gets you the full book, introduction and data, but it is not updated. This download will be the version of the LL that was up to date at the end of the previous year, ie week 52 of 2015. You get the same product here downloading in April as you would in November.

You have two ways to keep this Annual LL up to date. You can download just the changes that have occurred this calendar year since the annual edition was published, or you can download the full book as of the week of the download, but this file will not include the important front matter mentioned above.

(2) Summary of changes only

Using this solution you would have to have a copy of the annual edition as these are just the changes. These are small files (~250 kb). The practical application would be look up your light in the annual edition then do a quick check in the updates file.  You can do this fairly quickly because every ATON in US waters has a unique number, and that number is listed on the left of every entry, ie for ebook editions we just search on that number.

(3) Updated editions with optional front matter.

This seems a good approach. Just download the front matter once (~3 Mb) to have this important info somewhere available to you, then download the full set of data as needed to keep your LL up to date in one file. Then when underway you have just one file to look at. These files are about 800 kb.

The date of each of these is printed next to the download link in terms of weeks. The one I am looking at now is called Week 26 of 2016. Week 26 is June 27 to July 3, so this being the 4th is right. Again, the weekly updates can be up to 3 days late. It is also shown on each page of data as shown below.

When leaving for a trip, go to link (3) download both files (front matter and latest contents) and you are done. You have the front matter and you have the LL up to date at the time you leave.  That is the best we can do.  

Broadcast Notice to Mariners
If a crucial light does change once we are underway, then we can hope that it is reported by the USCG on their twice daily VHF broadcasts of the Notice to Mariners. They announce this on channel 16 then give the reports on 22A.  Publication 117 Radio Aids to Navigation tells when these are broadcasted if we want to focus on that without relying on the channel 16 announcement.

Or, for the navigator who has everything, you can request that all warnings and significant changes to ATONS be sent to your email directly at this page:

This is actually a wonderful service that you can try now, and then see how it might work for you with your onboard email service. It will also tell you when chart updates are available or other maritime notices... ie Navy bombing practice.

Canadian Light List
The Canadian books are also available with front matter and index separated from the main data, plus they offer the option to choose just the regional parts you need.  Thus when traversing Canadian waters as in the R2AK, you would select the regions needed and combine them for a custom version.

The Canadian LL is in principle updated monthly, but it is sometimes delayed as it must be released by the Canadian Coast Guard, which is a different agency than makes the actual updates.

When it comes to deciding the actual dates, we are almost certainly safe by just downloading those files, but there is some apparent inconsistencies in the date descriptions.  The individual sections are annotated with a date as shown below...

...but the actual pages in this section are each marked as last updated 5/16.
And when we check the front matter section, we get a bolder statement, with a still different date of 6/16.

In short, I think this means:  this LL was updated with all corrections as of June, 2016, and within the Straits of Georgia section, the last change (whatever it was) was made in May, 2016. This does not explain the date on the download page (2/16), which might be just an error. (They are checking that for us and I will learn shortly.)

Thus for our "truth meter" for deciding which light data were right in the short course, we can assign June, 2016 to the Canadian LL data.

But back to the ENC point raised at beginning...
If you own the latest official Canadian ENC charts for your region of interest,  the ATON data on them is the latest available and can be relied upon as being same as the LL or better.  This is also true for the US ENC. The official Canadian ENC come with 2 years of updates for the cost of $199 for all of BC.  Canada also has an email subscription service for chart and ATON updates at

It is another matter to track down the  date of latest ATON data included with commercial echart programs that offer Canadian vector charts such as Navionics, C-map, Garmin BlueChart, MapMedia, and others.  These companies have a license to reproduce the charts, but no obligation to keep them up to date. When they do an update, we do not know what has been updated or what was the latest official chart was used. Some of these companies are known to be slow on updates, and in many of their apps you simply cannot tell what the latest edition actually is.  I have earlier addressed an issue related to that: Don't Blame eCharts for Anything.

Side note on ENC vs RNC.
We have several places pointed out the value of having ENC charts installed, even if you prefer routine navigation with RNC, because they are more familiar looking. The interesting thing I have learned is Canadian printed charts (now all Print on Demand) are also updated weekly, just as the US ones are, but the Canadian RNC made from these printed charts are much delayed, being at most once a month, and often longer.  They are not updated until the Canadian Light List is updated, which is on a monthly schedule, but often delayed as noted above. Thus they hold off on updating the RNC until the Light List is issued.

Put another way, with Canadian charts we have the unusual circumstance where the printed chart could be up to a month or more newer than the RNC that represents it, which is one more argument to have both the ENC and the RNC. Not only does the ENC sometimes add data to the description of the aids, it is almost certainly up to date if latest chart has been installed (which is not the case for the RNC).

Latest chart editions
To be sure you have the latest chart editions at departure, you can download these pdf files. For the US, we can assume that all formats are updated at the same time; for Canadian charts as noted above the printed charts can be earlier than the echarts.

            US Charts Dates of Latest Editions

            Canadian Charts Dates of Latest Editions


For an extended discussion of how to use the Light List see Inland and Coastal Navigation. The Light List is structured in a unique way, separating main waterways and secondary, and sometimes a light on the corner of these is tricky to find if we do not know its name, or it does not have a name. What we do know is, all lights and buoys are in there, somewhere, and each has a unique number.

A special thanks to the Canadian Department of Fisheries and Oceans, CHS, NOTMAR Division in Victoria for their useful information on details of charting and chart publication.

No comments:

Post a Comment