September 5, 2013-Making Charts
wingssail images-judy jensen
We love charts; charts are the navigator's treasure. The navigator hungers for the newest chart and he pours over each latest cartographic acquisition to see if there are details which his old charts lack, and to see if there are depths given for the tiny inlet he intends to traverse. The navigator loves his charts.
For years we collected paper charts. We had charts of all kinds, from NOAA, British Admiralty and chart copies, which were of dubious quality but which we could more readily afford. At one time we had several hundred paper charts, a stack over a foot high, and those charts provided coverage for most of the world. There was always a paper chart spread out on our chart table, often coffee stained and damp, with pencil marks and position fixes drawn all over it.
Then came electronic charts. We bought a set of CMAP CM93 charts from a book store in Port Vila, though they were certainly pirated, back in the year 2000. They turned out to be copies of a CMAP demo which had somehow gotten into the wild where it spread rapidly. During the years that followed most cruisers acquired and used CM93 charts and the CMAP program. They became a standard. Cruisers traded them with each other and still do.
We quickly adopted electronic charting but we held onto our treasured paper versions for years because who could trust the electronics aboard a vessel? Finally we decided we could trust the electronics, (as long as we had plenty of back-ups) and we sold the paper charts. We moved on.
Now we use OpenCPN, a program developed by some technically savvy boaters and distributed for free. It is very good. But the charts are still what make it useful and we now have updated versions of the CMAP CM93 charts. We have twenty eight thousand CM93 charts to be exact and we collect them as assiduously as we did our paper versions years ago. They cover virtually the entire world and the detail for most areas is astonishing. However, in some places, unfortunately many of the places we wish to visit, the detail and accuracy is lacking in CM93. This is because they were made for and are primarily used by commercial shipping. If the big ships go there CM93 has a great chart for it but for that small cove where we might like to anchor, well, sometimes CM93 isn't the best.
Many countries however still create paper charts and they are often far superior to the CM93 charts for those countries. Colombia is one of these places which makes charts and we have a good set of Colombian paper charts with much better accuracy and detail than our CM93 charts for Colombia. The Colombian Navy also has excellent electronic charts but these don't seem to be available for private use.
So what do you do when you can't get an electronic version of the best chart? You make one. I've long known it was possible to convert paper charts into electronic ones but it has always seemed too difficult. Now, though, to get these fine Colombian charts we have into our OpenCPN system I decided to learn the process and I've succeeded. With a scanner, Adobe Photoshop, a small conversion program called imgkap, a binary file editor, and some software I wrote in excel, I have worked out and perfected the process to convert paper charts into electronic charts. I have now converted a number of these excellent Colombian paper charts into electronic versions which are fully integrated into our OpenCPN system with our existing CM93 portfolio. They look as great on the computer as their paper versions do on the chart table. What is better is that I can repeat the process in the future with any good chart we find. This has been a fun project and a great success.
Now we just have to get out of the slip and use them.
Day on the water with friends
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Fred & Judy, S/V Wings, Cartagena