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Old 21-10-2013, 23:56   #1
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What's the difference between cm93 ed.2 and ed.3

I am new to cm93 and OpenCPN. But I am curious about something.

Okay, I understand that cm93 ed.2 works with OpenCPN, but ed.3 does not.

It seems likely this is because Ed.3 is a commercially supported product and Ed.2 is not.

Is that true? Is cm93 ed.2 a fossil, no longer maintained and updated. Is it falling out of date and in a few years will be dangerous to use?

Is ed.3 the product to own?
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Old 25-10-2013, 03:47   #2
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Re: What's the difference between cm93 ed.2 and ed.3

It all depends on what part of the world you sail in. The chart plotter suppliers would like you to believe that you allways need the latest and greatest and have a tendancy to change formats to force the issue. Most if not all charting is based on the same surveys. Cm93 ed2 had many corrections to shift some locations for better accuracy based on sat data etc. I would imagine ed3 has some more. I navigated from Columbia to Vanuatu with cm93, got ed2 in Vanuatu and found the accuracy improved and has been spot on through thr Solomons, Palau and Philippines. I still use mark1 eyeball thoigh for entering port. The google earth to kap feature of opencpn will help even more gor checking accuracy.
Bohol, Philippines
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Old 25-10-2013, 05:21   #3
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Re: What's the difference between cm93 ed.2 and ed.3

It's not the chart content and how up to date it is, but the format of the data. There was an overlap after Edition 3 was released, and Edition 2 was still being updated. As far as I know Jan 2011 is the latest CM93/2.

Edition 3 charts are encoded in version 3 of the S57 format and OpenCPN does not read that format. Here is Jeppesen's explanation.

Jeppesen Professional+ Background

There is another thread on here about the possibility of developing OpenCPN to read Edition 3.

Seriously, how much would it cost to get CM93/3 into OpenCPN?
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