Sunday, July 20, 2014

Finding Your Way...For Free

One of the more annoying aspects of owning a small aircraft was the limitations the FAA placed on navigation equipment.  Anything installed in a certified aircraft had to be approved by the FAA and this approval process was expensive and time consuming and the cost was naturally passed on to the customers.  Spending $15,000 U.S. or more to install a GPS navigation radio with a 3 inch by 4 inch screen was the norm. When small laptops and tablets became available, a whole new "affordable" option became available and now I don't know many pilots that fly without having one on board.

While chart plotters for boats are not as expensive, they can still be several thousand to purchase and install. And if you want to go low-tech and simply use paper charts for navigation these days, you may find it difficult to find a map (as noted in this story from Sail magazine).  My boat has a chart plotter at the helm, but my aviation days taught me the benefits of redundancy.Without finding reasonable cost paper charts, I've found a low-cost solution that both provides official charts and acts as a backup for my chart plotter.

Did I say low cost?  It is actually free.  The program is called OpenCPN and it runs on Windows, Linux, and Mac.  This program allows you to view both official electronic data just like your chart plotter as well as geo-referenced images (called raster images) of the official paper charts.  Below are a couple snapshots of the two views using the Beaufort NC inlet.

Beaufort NC Raster Image (chart) view

Beaufort NC Vector Data (chart plotter) view.
The electronic chart plotter (vector) data view is a bit cluttered in the above image but I wanted to show you some of the detail available.  When you zoom in or out of an area, the application will automatically filter the data to make it more readable.  Zooming in or out of the chart (raster) view, the application will load the maps at the appropriate scale (provided you have downloaded them) so you can see details when you need to or get the "big picture" view when viewing a whole region.

The software alone is sufficient for reading charts and navigational data as well as planning routes. Oh, and did I mention that it can load and display GRIB data too?  You can display predicted wind speed and direction, pressure bands, wave height, currents, etc. right on either view (but you may need to zoom out a bit more than depicted above to see it).

OpenCPN is the application to view charts and navigation data, but it does not come with that data.  Instead, it reads chart data from a variety of providers.  In the U.S., NOAA provides both the electronic chart plotter (vector) data as well as geo-referenced chart (raster) images for free.  Other countries provide one or both data types for free or a nominal charge.  The OpenCPN site provides an overview of where you can find charts for various locations here.

The software can also display position and course information provided you can provide GPS data to the program.  This shows you where you are at any given time and can also record tracks (all the tracks I've posted on the blog recently are images from OpenCPN) and provide basic navigational information like course and ETA.

I want to provide more detail on how to download and setup the application and charts, as well as a couple of ways to get GPS data to the application (including a free one if you have an Android based phone), but this post is getting rather long I guess I'll be doing a part 2.

In the meantime, if you want to check out the application, you can download it and/or find installation instructions here.  Documentation can be found here.  For the current U.S. chart (raster) images, you can get them here.

I assume most cruisers, at least the ones reading and writing blogs, carry one or more computers on board so this should be a low cost option for navigational data.  And even if you don't have a supported laptop, you should be able to get one for 10~20% of the cost of a dedicated chart plotter.  And it is generally easier to update the software as things change than it is to update your dedicated chart plotter.

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