Saturday, June 8, 2019

Best International Chart Deal Ever!

Well... that's a bold statement; let's clarify.  First, I am speaking of charts that are equivalent to official charts, as opposed to 3rd party charts, such as  Navionics or Garmin Blue charts, among others. Both of these can be good in some areas; both can be bad in some areas.  Sometimes these limitations are not just the chart, but the chart viewer. In most cases, these chart companies control the viewers, but some platforms are more versatile than others. Once these proprietary charts are then sold or licensed to other companies, more issues can arise, as they might, for example, license only some scale levels and not others. There have been notorious accidents traced at least in part to that issue.  But none of that matters here.

We can use paper charts or electronic charts (echarts), but for a "deal," we would have to mean echarts, because all paper charts are expensive, and rarely on special. Also of course, by "international" I mean waters other than the US waters, because all US echarts are free—the obviously best deal. A few other nations also offer free echarts for some of their waters (see charts section at OpenCPN).

Echarts come in two formats: raster navigational charts (RNC), which are graphic images of the paper charts, and vector charts, which are all digital data; the chart display is created 
from numerical parameters by the nav app as we view it. Vector charts can in principle include much more information than possible with raster charts, such as Light List and Coast Pilot data, as well as more descriptive attributes of the various charted objects. The bargain here is with the vector charts, because they are smaller files than RNC, and they are notably easier to maintain, manage and distribute, not to mention having the potential to include more information.

All maritime nations make a set of vector charts in the official IHO standard called S-57. These are called electronic navigational charts (ENC). The third party charts mentioned above are all "vector charts," but they are not ENC, and therefore not official charts.

To understand this "best deal ever" we need to look a bit more into how ENC are displayed in navigation apps, which is outlined below, but I should mention that we have a book on the design and use of ENC charts that includes all the practical detail needed to take advantage of the powerful ENC resource, as well as explaining relative roles of RNC and ENC. It also includes tips on use of echarts in general.

"Great book! I wish I had had this resource many years ago when just starting to craft OpenCPN. Would have saved me lots of effort pulling together the sometimes baffling set of standards and connected parts that is the current ENC landscape. Especially, having ENC Chart 1 available in clear color printed form is a huge benefit. And the annotations are a bonus. Well done! I will heartily recommend this volume to OpenCPN users as the opportunity presents."
—Dave Register, originator and lead developer of OpenCPN.

ENC products must include all the information specified in the IHO S-57 standard, but that standard does not tell us how the data should be displayed to the navigator. The display of the data is specified in IHO S-52 standard, and any navigation app or system that hopes to be certified "Type Approved" must meet the S-52 display standard—and indeed several other factors having to do with interface, chart updating, and back-up.

In passing, the ENC display in OpenCPN is as good as any we have seen outside of type approved apps, and indeed some of the choices made in OpenCPN that are not strictly standard could be considered an improvement by many navigators. The developers at OpenCPN have been very good about making improvements in the display whenever needs are detected.

The common factor among all nav apps capable of showing ENC, whether or not they are type-approved, is the way they process the chart files. Upon initial install, they load the standard ENC file issued by the producing Hydrographic Office, and the first thing they do is convert the ENC files to a format they can read and display efficiently in their own system, and then they store this new file on the hard drive along with the original ENC. The new file is called the System ENC, or SENC file. A SENC file is some 2.5 to 5 times larger than its base ENC, depending on the nav app and individual charts.

Thus every navigation app running official ENCs will have two copies of the chart installed. The government ENC and their own unique SENC file. The ENC files of a specific chart are the same loaded into any nav app, but the SENC files created in that app are unique to that specific nav app. 

Other than from the US and a few other nations offering free ENC in S-57 format, most maritime nations package their ENC into an encrypted format called IHO S-63. This is basically a protective envelope they wrap around the ENC, whose content is still determined by S-57.  OpenCPN has a plugin to allow for the display of S-63 (ENC) charts, but these charts are not the subject at hand now. The S-63 official charts are all fairly expensive.

Since international ENCs are encrypted (for copy protection and to guarantee accurate data), you cannot even create a SENC file without having needed credentials on your computer, which typically include some form of a fingerprint of your computer system along with a chart serial number that is proof of purchase of the chart. Therefore it is no surprise that you cannot just copy the SENC file of a chart and send it to a friend using the same navigation app.

The IHO has, however, approved the distribution of SENC charts that have been created by licensed providers, but these charts may not be referred to as "official charts," and indeed as such would not meet carriage requirements.  They do this in part to protect their official chart sales, but also because they did not make the actual charts themselves and therefore cannot guarantee that the charts are indeed identical to the official ENC, nor can they guarantee that the update system works as intended.

The special deal on international charts referred to here are SENC charts produced specifically for OpenCPN by, a company of sailors in Barcelona.  Since every nation has their own regulations on the use of their SENC charts, the License agreement from o-charts lists them all.

Not all nations offer this SENC option, but many do, and this does indeed look like the future of electronic charting. It has the advantage of being a machine language file that runs fast, and takes up half the space of a native ENC installation—and as we see here, companies have the option of providing these at very economical costs.

I must also add, another thing that contributes to them being the "best deal" in charts is that they are made for OpenCPN, which is a topnotch nav app. There are several very good commercial nav apps, but there are others that are not very good. Had one of the poor products offered the SENC charts it would not be such a good deal. As noted below, there are indeed international charts that cost less.

The limits on the SENC charts are they are unique to the navigation app they are made for, and second, they are not "official charts." The providers (o-charts) can and do state that the charts are identical to the latest official versions, and they include free updates for some period of time, typically one year. The SENC charts we have tested have indeed been identical to official ENCs, and the update process works well.

The primary reference for ENC and SENC related matters is the excellent IHO Pub. S-66 Facts About Electronic Charts and Carriage Requirements  (SENC is on pages 13 and 31-34).

So with that long introduction, the deal we are discussing here are SENC charts made for OpenCPN, available from  This company is licensed by the nations that offer a SENC option. They produce the SENC chart files for OpenCPN (called 0eSENC, OpenCPN encrypted SENC) and then they sell and distribute these oeSENC directly to us without any interaction with the primary ENCs. One year of free updates is included. Nations update on different schedules.

We have tested this system, and it works well. Easy and efficient. And indeed a deal! You can, for example, buy all of the charts of Australia (889 charts!) for 35 euros (~$40). The ENC cost is about $580. The international selection of oeSENC charts available is given here.

For comparison shopping, o-charts offer all of West Coast Canada (BC) for 20 euros. The ENCs from Canada are some $1,200!; the best previous bargain I knew of was Rose Point price of $99, but they can only be used on their nav app Coastal Explorer (these are S-63 not SENC), which is an excellent navigation program but is costs $365. Rose Point does have the BC raster charts for $99 as well, again restricted to Coastal Explorer. O-charts says they are working on raster versions as well, but that is a big project... recall the notes above on why vector charts can be a bargain. 

In further contrast, I must note for completeness that the least expensive of all electronic chart  options are the Navionics apps for mobile devices, and in this case the one called "Boating US & Canada." That is just $22 for nav app and charts for all US and Canadian  waters, but the charts and app both have notable limitations. It would be stretching the point to call its use navigation... it is, as they describe it, "boating." To be fair, however, very many prudent navigators have in fact used the Navionics charts in one form or the other around the world, for short and long passages. But they have to be on top of things at all times, to deal with anomalies that might show up.

I am using OpenCPN 5.0 on a Mac, but users should double check that any crucial plugins they want to use are available for ver 5.0 on the Mac. At this moment, the Mac plugins are in process. All the standard plugins work for the PC ver 5.0. As it might be called for, there are multiple ways to run the PC version of OpenCPN 5.0 on a Mac, which I will review in another article. Several are free; others have just a modest cost.

The license you purchase from allows for two "installations," where each installation identifies the computer and its operating system. If you update your OS it will look like a new computer and you will have lost one install. Thus we have to think carefully on these matters. 

An alternative approach available only to PCs at the moment is to purchase a dongle from o-charts for 19 euros, and then one of the "installs" can be assigned to the dongle. This does not put the charts on the dongle, just your registration credentials for specific charts. Then you can plug the dongle into any PC or OS to make that system a legal viewer, but now it can be moved from one system to another. The system would of course have to be running a copy of OpenCPN, 4.5 or newer.

To use these SENC charts from o-charts you will need the free oeSENC plugin for OpenCPN. It is a simple install and the process of buying the charts and then creating the fingerprint is straight forward. 

I am going to order a dongle (total of 23 euros ~$26) to ship to the US. Then I will purchase the Canadian BC charts and make a video of the full process to add here.

In the meantime, there is an excellent video on the step-by-step process of obtaining and installing these charts made by o-charts.

There is no audio with the video, but that is not needed. It shows clearly every step.  Keep in mind the OpenCPN is an international product, with more language versions than any other navigation app, so no one language meets all needs in the demos. This video does not include the step of building and using the fingerprint file, but that is covered in the articles below.

...and somewhere down the line we do have to make our promised video series on the use of ENC, because ENC are not plug and play. They include much more info than raster or paper charts, but it takes a new approach to  chart reading to take advantage of them, which our book above provides.

Thus it is important that you know the type of chart you are getting and how to use them. You can download and work with the US versions (see to see how they function, but our text on echarts (above) would help a lot with this (there are Kindle and Apple Books as well as paper). If you do not have that book, this reference from Claris on ENC objects and attributes will be helpful. This Russian version has a different format for the same data (—if the two differ, the Claris cite is more likely to be up to date.

Related Articles with video illustrations on O-SENC
    Revolutionary nature of dongle distribution
    Assigning SENC charts to a dongle

All about S63 encrypted charts


Hubert said...


the Australian oeEVC (=oeSENC) chart set contains more than 650 single charts.
Coverage includes PNG and the Solomons.


David Burch said...

Thanks very much Hubert. I have updated the article with the actual count we have, which is indeed even higher (>800). We now have a dongle and will practice loading charts onto it and follow up with another video. We are behind at the moment.

Unknown said...

Do we have opportunety to use the e-book of navigational chartworking for free?
Best regards..

David Burch said...

No, I am afraid not. The book is available in several ebook formats, but these are all commercial products at $19.95. See

Our list of ECDIS chart symbols is an expanded and annotated version of what you can get for free in Chart no 1 at

You can also get for free a list of objects and attributes at

But only the book itself has the discussion of practical use of echarts... note too that in 2024 there will be no more US paper charts nor RNC echarts, so everything will be ENC. Follow this blog for more notes on that process and related issues.

Unknown said...

Okey. Thank you for your answer and advise. Also your youtube channel that I follow is very useful.

Helge Thorsen said...

Hi David
I have been looking around for purchase S 63 chart for using in QtVlm but sofar with out luck - do you have some link where to buy this?

David Burch said...

We just posted a note on that exact topic! Please see

And thanks for your question. I will also add this to the article above, which i had forgotten about.