Review of Nautical Chart Symbols App

Looks Good at First, But Can You Trust It?

Nautical Chart Symbols App
Nautical Chart Symbols App.

Nautical Chart Symbols is an app for Apple devices that provides the meaning of many symbols and abbreviations found on marine charts. Since all responsible boaters use charts, and few carry a reference text that explains absolutely everything you might see on a chart, an app that quickly and easily describes what you're seeing right now on your chart would have great value when entering unfamiliar waters.

Nautical Chart Symbols purports to do just that. While the app-maker's description does not actually promise that all chart symbols and abbreviations are included, it works hard to give that impression - and when you start scrolling through its long, long listing, it does seem pretty complete at first. Unfortunately, it actually leaves out a great deal of information that is provided in NOAA's Chart No. 1 - the official comprehensive list of all chart information (and the apparent public domain source for the app's information). Only when you compare the app with the NOAA publication do you see how much has been left out - and the trouble you could get into if you needed to know what something on your chart means and the app lets you down.

Version reviewed: unidentifiable. Current version: 1.5 for iPhone, iPod Touch, and iPad
Developer: substatica. $1.99
Not currently available for Android devices
Note that a different chart app from has the same name: Nautical Chart Symbols

What It Does

The NOAA Chart No. 1's descriptions and explanations of chart symbols and abbreviations runs to 91 full-size pages. I'd estimate that roughly 60% of this information appears (often in abbreviated form) in the Nautical Chart Symbols app. The app organizes the information in the same 17 classifications as the NOAA source, and you essentially scroll down in a very lengthy vertical list to find what you want within one these classifications:

  • Positions, Distances, Directions
  • Natural Features
  • Cultural Features
  • Landmarks
  • Ports
  • Tides, Currents
  • Depths
  • Seabed Condition
  • Rocks, Wrecks, Obstructions
  • Offshore Installations
  • Tracks, Routes
  • Areas, Limits
  • Lights
  • Buoys, Beacons
  • Fog Signals
  • Radar, Radio, Positioning
  • Services

The app also has a search function intended to prevent having to scroll endlessly to find what you're looking for, but its functionality is crude. You can only search for words in the meaning of a symbol or abbreviation - not for the abbreviation itself. For example, if you saw MLW on the chart, your search for "MLW" produces no results. If you already know that MLW stands for "mean low water," then you can search for that to find the abbreviation MLW - but of course if you already knew what it meant, you probably wouldn't be looking it up!

And of course there is no way to search for symbols - which is what one usually sees on a chart and wants to know the meaning of. Quick: is that a submerged rock 3 feet below low tide depth or a rock that exposes 3 feet at low tide? Scroll, scroll, scroll, scroll - and eventually you'll find out. It would have been nice at least to have a table of contents at the top by which you could jump to the right section of chart symbols to speed things up.

The Downside

The very limited search and navigation functions mentioned above provide a clue to the weaknesses of this app in general. It looks like it was created very quickly, essentially by dumping uncopyrighted information from NOAA into the easiest possible format to program, and then stopping. Rather than offering more than its paper source, it offers considerably less.

I spent some time doing a side-by-side comparison of the app with the NOAA source and saw quite a number of things left out here. Most of the NOAA symbol charts have three columns, and I won't go into the technical differences between column 1 symbols and column 3 symbols - but I quickly discovered that if column 3 was blank (even though there was a column 1 symbol for the item at hand), the app simply left it out. So the result is that, for example, you can see the symbol for a groin that is always exposed above the water, whereas the symbol for a submerged groin is not included.

Hope you don't hit one while you're trying to figure out what that symbol is! Same thing with jetties. That seems also the reason why many simple abbreviations have been left out - if they were only in the first two columns. So no meanings for var, dev, fms, brg, and so on.

Another oddity is the occasional weird language. Where NOAA gives the symbol for a fixed bridge with "Vertical clearance above High Water," the app says "Vertical clearance above the plane of reference for elevations." Huh? Maybe the app author was using an out-of-date source?

Most damning, however, is simply the information left out. How can you trust a resource for chart symbol meanings that half the time is missing what you might need? Quick: what are those weird squiggly lines? Breakers along shore, NOAA tells us - the app, silence. Quick: what in the world is that? An eddy, NOAA tells us - the app, silence. What does FVQ mean by that symbol there? It's a light flashing very quick, NOAA tells us - and you get the rest of the story.

The class of symbols most lacking is Lights, which of course can be crucial for boating at night. NOAA gives six full-size pages of symbols and abbreviations for lights, but because this information is laid out in a way more complicated than the usual 3-column table (two of which the app programmer uses), the programmer seems to have simply grabbed only the easiest stuff to stick in: one small screen from all that detail presented in six full pages.


If you've read this far, you no doubt already know my conclusion: be wary of this app.

It's fine to have it with you if you also have a full reference for times when it's needed. And it's better than nothing if you don't have a reference on your boat (like Chapman's Piloting: Seamanship and Small Boat Handing). But that's sort of like saying it's good to have a quart of water with you if you wash up on a desert island - wouldn't it be better to have a few gallons?

For any boater who sails into unfamiliar waters and wants to understand what he or she sees on the chart, carry a book like Chapman (full of lots of other great information too), or at least visit this NOAA website to download the free pdf of Chart No. 1. Put that on your iPad or laptop to carry along, or print it out and stick it somewhere on the boat for when you might need it.

Of course, a lot of boaters these days are used to using only apps for navigation and other purposes, so for them, maybe a chart symbols app is the most practical thing.

A great solution would be if the next edition of the Boater's Pocket Reference app were to include all chart solutions into a generally excellent reference source. While you’re thinking about sailing apps, check out the neat little AyeTides app for tide and current information.

Finally, any serious cruising sailor or one headed for new waters would gain much from having aboard Nigel Calder's book How to Read a Nautical Chart, with extensive detail on all chart symbols and information as well as helpful chapters about GPS and chart accuracy.

Another Android and iOS app of the same name, Nautical Chart Symbols, may be better for you.