Navigational Software Packages

The Passagemaker Experience by First Mate Louise Visagie

As at March 2012

Few of us still take the trouble to pick up pen and paper to write letters to friends and family. Similarly, it is only the “hardcore” old hand at yachting who still resists technological advances and who, as a rule, uses paper charts in stead of electronic navigation (generally the same type to row ashore in stead of using a dinghy with outboard). On board Passagemaker, we have tried out a number of navigational software packages and would like to share our experiences with fellow yachtsmen and cruisers out there. Most notably, the fact that it is now possible to download all software and electronic charts required to sail the best parts of the world ... for free! All that is required is:

(1)    your laptop,

(2)    a decent Internet connection to download the necessary software and charts,

(3)    a connecting cable to link your particular brand of GPS to your computer,

(4)    a little bit of patience and, hey presto, the world is your oyster.


Electronic chart types

For the small few who still patiently plot GPS coordinates on paper, take noon sightings by sextant, or consider themselves to be technologically challenged, a few words on electronic chart types. They are neither as daunting as they may appear at first glance, nor difficult to use. Two main types are available, vector and raster charts...

Vector charts contain “layered” data - this means that when you use your computer to zoom in or out, your chart automatically changes scale and displays or hides information, maintaining graphic resolution and quality. This is similar to approaching port and returning your small scale chart to the chart table while removing a larger scale chart (amidst a shower of protractors, pencils and parallel rulers...), the latter containing more details and being clearly readable.

The most commonly used set of vector charts is the CM93 set, well known to yachties who have the ubiquitous MaxSea software. The great news is that the latest set of CM93 charts (2009 edition) are now available as a FREE and completely legal download. Having sailed a good number of rivers on Passagemaker (and with river charts being notoriously inaccurate or deficient in detail, often placing the ship on land!), we can vouch for improved accuracy of this latest set of CM93 charts.

All other vector charts are only available if you are willing to forego your weekly T-bone steaks and good quality rum in order to put your hand deeply into your pocket. Not only are these charts sold on expensive electronic cards (each card’s charts only covering a certain region), but you’re also likely to need a chart plotter to read them. Another dent in the cruising kitty. That being said, a nice chart plotter and good Navionix charts are super for ease of use, if you can afford it! In our opinion though, you can acquire virtually exactly the same utilities for a tenth of the price. (Bring on the El Dorado rum says the captain).

Raster charts, as the second electronic chart type, only contain one set of data which is always visible and is not “layered”. When zooming in, no further details (e.g. depths) appear and the picture resolution eventually deteriorates. In other words, zooming in on a raster chart is like using a magnifying glass to look at your paper chart ... nothing new will appear – it may help you to read things more clearly up to a point, thereafter it just becomes a blurred mass!

There are many different formats for raster charts, and each software package has restrictions in which type it can “read”. It is however possible, though not always easy, to change raster charts from one format into another by using free utility software available on the Internet. In stead of approaching this issue from the perspective of the charts, however, we’d rather recommend that you look at what software works best for you (and your computer) and to take it from there.

Some of the raster chart types you’ll encounter are as follows (known by the file extension, in the same way that a Microsoft Word document is DOC or DOCX):

 (1) KAP and BSB

(2) WCI, and

(3) MAP charts.

From the above it may sound almost foolish to use raster charts when vector charts are easier to use and automatically layered. But there are two main benefits to raster charts... First, many charts available as free downloads on the Internet are raster. And second, it is possible to calibrate your own images into raster charts! This means that you can take any old image file, even pictures of charts taken with your camera, like a JPG/JPEG or TIFF or GIF or PNG and, if you have enough information about the surface it covers, convert it into a chart to use with your navigation software!


Where to download free and legal electronic charts

The following websites all provide free chart downloads, and we’d welcome feedback from anyone who discovers other sites that could be added to this list. Be mindful, at the same time, that you are likely to trade charts with fellow cruisers as you move along. Now some of them may be of good quality, while others are scanned images from horrendous photographs. As with sailing in general, use your common sense and deciding for yourself which charts are safe to use for realtime navigation.

CM93 vector charts: covering the entire globe, available at www.xxxxxxxxxxx

NOAA raster charts: covering all US waters, inland and offshore, at

KAP/BSB raster charts: covering the Brazilian coast, Brazilian rivers, and a small area of the Antarctic are available form the Brazilian Hydrographic office at

MAP raster charts covering Argentina and Chile at www.xxxxxxxxxxx

New Zealand at www.xxxxxxxxxxx

South China Sea atwww.xxxxxxxxxxx


Navigation software packages tried on Passagemaker

This is by no means a comprehensive list of nav software available, simply what we have personally put to the test.

MaxSea ... Most yachties still swear that MaxSea is the uber laptop software to use for navigation. And if you’re the type of cruiser who gets a kick out of planning convoluted passages requiring complex plotting and enjoy editing signage down to the detail of shape, size and colour of your waypoint icons, this is probably true. On Passagemaker, we prefer our nav software to assist our passage from A to B with the minimum amount of hassle, hence we’ve found MaxSea to be “too much”. Too many toolbars, too many menus, too many options. Plus, it can be hell to install this software and get it to read your GPS. Also, many versions have issues with older/newer operating systems (XP, Vista, Windows 7, etc.).

                Views: vector CM93 charts

Nimble Navigator     

Developed by Quinns Apps. this simple to use nav. software took us right round the Caribbean.

Tide Chart   The tide charts for most places in the world are particularly handy.  A bargain at US$95.

                Views: vector CM93 charts


OpenCPN ... FREE software available for download at designed by cruisers for cruisers. This has rapidly become our favourite nav software. It has a good balance of aesthetically appealing displays, intuitive and user-friendly toolbars, and functionality. It is easy to move between charts, to zoom in and out (using the roll bar on the mouse), and to navigate the cursor around the screen. Especially useful is the option to “quilt” charts. That is, when two charts may not be perfectly aligned or of the same scale, OpenCPN will “stitch” them together so that there is a seemless flow of charted area across the screen (at whichever scale you prefer) as your boat moves along, keeping the ship’s icon in the centre of the screen. Another unique feature is the option to not only import satellite images from Google Earth, but to overlay these images with your charts and – by rendering a degree of transparency to your charts – view the depth readings from your charts on the satellite image!

Doing the latter requires the download and installation of FREE Google Earth software from  and FREE GE2KAP software to convert Google imagery to KAP files at This software has been developed by Paul Higgins and if you use his software please be sure to send a small donation to help him feed his dog J

Also useful is the fact that the developers of OpenCPN, all yachtsmen, run a Facebook page where you can have any queries answered almost immediately.  

                Views: vector CM93 charts, raster KAP/BSB

SeaClear II ... FREE software available for download at or “Click Here” to download a free copy. When not using OpenCPN, we use SeaClear for its additional uses. The display is not as pleasant while using the toolbars and menus requires a tad of patientce to master at first (moving between charts is a pain), but the software does come with an extremely detailed  user manual. In fact, arbitrary critics on the Internet claims that between OpenCPN and SeaClear, the latter is far more functional. We mainly use it for the MapCal (“Map Calibration”) utility which is also standard with the package. This calibration tool will convert just about any image file (JPEG, TIFF, BMP) into an electronic chart, with the bare necessity of entering a number of calibration points (known coordinates for points on the chart). The more calibration points you use, the greater the accuracy of your chart. Preferably one should also possess data on the scale, projection, depth units and datum of the image to be calibrated. Again, the user manual clearly explains how to use these features.

                Views: raster KAP/BSB, raster WCI



So go out there and start downloading. Any laptop will do and a GPS stick which will plug into any USB port and which looks just like a memory stick (see picture below), cost about US$40. Go to Amazon to buy.USB-GPS

 Incidentally if you plug your USB GPS in and cursor sometimes jumps all over the screen  here's the fix: 

Open Regedit. Navigate to
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SerMouse, and change the value "Start" from 3 to 4.  Reboot.

There is a reg file that will do the editing for you also.