Keep Your Own Charts Current

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With the right connections, you can have the absolute latest critical information on your nautical charts.

With the right connections, you can have the absolute latest critical information on your nautical charts. You still may run aground on an uncharted sandbar or rip open your hull on the mast of an unreported tugboat. Those hazards, whether newly created or never before found, are the perpetual “unknowns” of navigation. But there are two ways to keep current with the “known” hazards.

Read the other stories in this package: Scanning the depths   It’s all in a day’s work…on the water

One way requires diligence, the other dollars. And in the future, a new international system being created by NOAA and agencies in other countries promises to provide an electronic early warning system for every mariner. The so-called electronic navigation chart, or ENC, will know your boat’s length, beam, draft and speed, and will issue warnings of approaching hazards and sound alarms when you reach these obstructions. But that is for the future. For now, the options are dollars and sense.

Every week the Coast Guard generates a preliminary Local Notice to Mariners that lists all new information about hazards to navigation discovered the previous week. “We have a branch that’s specific purpose is running an update service,” says NOAA Capt. James C. Gardner, chief of the agency’s Marine Chart Division, which reviews the preliminary notice and checks it for accuracy. “We make sure what they are getting ready to tell the mariner makes sense by plotting all that information on our charts and giving any changes to the Coast Guard. So the mariner who uses our [paper] charts has to take the Coast Guard Notice to Mariners, and sit down and make pen-and-ink changes to the paper charts.” (The final Local Notices to Mariners are available at

That laborious process, however, can be avoided by opening your wallet, according to Gardner. “Maptech comes in once a week and downloads the most recent digital masters, and they generate an [electronic] update file … that can be distributed to their customers.” Those customers may be recreational boaters or commercial mariners with chart plotters, or other software vendors, Gardner says. (Maptech — — has an exclusive contract with NOAA to distribute this information.) When a boater pays Maptech, they can update their plotter cartography immediately with the new navigational information, Gardner says.

NOAA also has an agreement with OceanGrafix LLC to distribute print-on-demand charts, Gardner says. “If a mariner goes into a store to buy a chart … [he or she] can buy a lithographic chart or a print-on-demand chart.”

What the boater gets with print-on-demand is a paper chart on the same quality paper as an off-the-shelf chart but with one-week-old navigational information included, Gardner says. OceanGrafix deals through a network of 13 chart stores and all West Marine stores, according to spokesman Larry Kocon. Charts can be printed at some locations or will be shipped overnight by others, he says. The price of on-demand charts is $21.35, he says, compared to about $19 for a NOAA chart without updates. Overnight delivery may result in an added charge, he says.

While the plotter software can show your vessel moving across the chart, “there’s no intelligence to those kind of charts,” Gardner says. ENC technology, now in use on large ships, provides the intelligence, he says. While the hardware to use ENC is too bulky and expensive for most recreational boating use, improvements should eventually make the system available on a smaller and less expensive scale, he says.

ENC is not actually a chart but a “spatial database,” according to Gardner. In practical terms, ENC produces an image on a screen that looks a lot like a chart. The programming language used allows a computer to create three types of features: points, such as a rock, piling or buoy; line features, such as a shoreline, pier or bulkhead; and areas, such as the Atlantic or a section of a channel. The image shows soundings and other typical chart information, and radar information can be superimposed on the graphic, showing where other vessels are, Gardner says. The radar information and the ability to issue warnings and alarms are designed to reduce the likelihood of accidents and ecological disasters, he says. Whether the ENC prevents accidents obviously will be, in part, up to the mariner, Gardner says.

“He may want to turn the alarms down,” he says. “It’s like when seatbelts first came out,” and drivers found ways to defeat their alarm mechanisms. “The mission of my division is to get the best information possible out to the mariner. I can’t force him to use it once it’s out there.”