Updating Your Charts

By Eric Jorgensen

As a follow up to Dave Norris’s article last month, this month’s safety corner will expand on that information and offer a few suggestions to keep you from discovering recent changes to navigational hazards the hard way.

The first step to ensuring that you are navigating with safe charts is to know what charts you are actually navigating with. This may sound obvious but in an informal survey of a random sample of sailors I discovered that less than one out of 15 actually knew when their charts were last updated. The ones that “knew” had just bought brand new electronic chart plotters and were certain that the charts that were included had to be the most recent ones available (NOT a good assumption).

The second step to keeping your charts up to date requires knowing how often chart updates are available. The National Oceanographic Atmospheric Administration (NOAA) is the agency that is responsible for keeping marine bathymetric data current. They maintain a master electronic copy of every chart. As new data arrives this master chart is updated and then made available to the public via the NOAA website. The master copy is based on paper charts and since the BSB charts are simply a raster copy of the paper charts they are the first to be updated. NOAA also makes vector or ENC charts available to the public that cover many of the same areas but these may take several days to several weeks to be updated compared to their BSB counterparts.

Print-On-Demand charts are one of the quickest ways to obtain an up to date chart. NOAA stopped printing their own charts several years ago and they now contract with third party vendors to make printed charts available to the public. These companies are linked directly to the NOAA master chart database and they print up-to-the-minute accurate, traditional, multicolored NOAA charts on waterproof plastic paper right when they are ordered. Usually they will ship the chart via overnight or 2 day shipping directly to you. All of these high quality charts meet all USCG carriage requirements. Most of the companies that offer this service provide additional information on their charts such as contact numbers or VHF channels for local services or marinas, hours of lift bridge operations or anything else that they feel might be helpful to the mariner.

If you use an electronic device that runs a navigation program or app that can directly import NOAA charts such as iNav-X or OpenCPN, then you can download the most recent official NOAA BSB charts from NOAA’s website just before you head off on your day of sailing the Bay or on an extended journey and be confident that you have the most up to date information available.

Electronic versions of charts are generally not updated as frequently or as quickly as Print-On-Demand paper charts or actual NOAA BSB charts in digital format since it takes time for third party chart makers to implement and release their updated charts.

Dedicated chartplotters utilize either proprietary or third party electronic chart data cards. These traditional chart cards cannot be manually edited by the user so the only way to update the chart is to replace it with a more recent chart data card. Since these traditional chart cards are expensive, updates are accumulated over a fairly long period of time and new versions are only released once a certain number of changes and/or a critical change that is particularly dangerous to the average boater has been collected. Navionics, the largest third party chart vendor and the supplier of charts to most marine electronics manufacturers such as Raymarine, Lowrance, Simrad, Standard Horizon and others, has recently released a new product called an Update Chart that allows chart updates to be obtained online from their secure server and then downloaded to the chartplotter via the SD card. In reality the Update Chart is actually a one year subscription to the Navionics update service which currently costs $99 per year and includes unlimited downloads. Garmin does not offer a similar product since they use proprietary, traditional chart data cards, but they do usually include one free chart update with the purchase of a chartplotter so you can at least have up to date charts when you originally buy the unit.

Step three of chart updating is to actually update your charts! If you are using paper charts then you have two choices to keep up to date. You can download all of the Local Notice to Mariners (LTM) and Notice to Mariners (NM) for your area going back to when your chart was last updated and then manually alter your chart by writing in the changes. Or you can simply buy a new paper chart.

If you navigate with electronic charts then you have several options as well. If you use a program or app that uses NOAA charts, simply download the new charts and replace the old ones on your device.

If you have a dedicated, installed chartplotter your choices may require a little more thought. If your chartplotter uses Navionics charts then do yourself a favor and just go buy the update charts. It is well worth the $99 investment. If you use a different type of electronic chart then a cost vs. benefit analysis may be in order. Since a traditional chart data card can cost anywhere from $150 to over $1000, it would be nice to know if the changes implemented on the new card is worth the substantial upgrade cost. One way to determine this is to choose the area that your chart covers and then make a map showing all of the changes since your chart was last updated (see Figure 1 below). I will admit that this is not easy to do and requires a certain amount of time and computer savvy but it may be a beneficial exercise if your charts are not too old and the cost of the update is high.

For those of you who are certain that your 10 year old charts are still just fine, Figure 1 shows just some of the changes to our local area since February 2011 (which is only 4 years for those who hate to do math).

Notice that there were 731 changes which include adding, changing or removing navigational aids, changes to depths, additional hazards to navigation, changes in the position of marked channels, changes to rules and allowed passage through restricted areas, changes to the positions of boat cats and more. These changes include many navigational aid changes along the San Francisco City water front and in the Oakland Estuary among others. For a typical area covered by a chart plotter’s data card it is not unreasonable to expect many tens of thousands of changes over the course of just a year or two.

The importance of having up to date charts cannot be emphasized enough. I have personally witnessed or have received direct accounts of several incidents this year alone which have resulted in damage to vessels or danger to crew that were a direct result of out of date charts. It is far too common for sailors to believe that they know their home waters so well that an old chart is “good enough.” It isn’t. Navigation lights get repositioned and change patterns. Channels are rerouted. Obstructions appear. Depths change. Boats sink. The only way you are going to know about these changes is to keep your charts up to date.

Fair winds and safe passages!