The CM93-2001 set came on 2 CDs. CD1 has a number of folders, of which the CM93 and CM93ATTR folders appear to be the key. The CM93 folder contains the charts, and also a number of .DIC files which it appears openCPN uses to interpret the charts. CM93ATTR contains a bunch more .DIC files that again openCPN seems to need. Everything else is optional. Mine had a copy of CMAPENC viewer, which is fairly terrible, but which you could use to verify the charts are ok.
CD2 only has a CM93 folder which contains the rest of the charts.
What I did: First, create a folder on the hard
drive named C-Map
. Then copy the entire contents of CD1 into that folder (go to the top of CD1, select all, and drag the contents to the C-Map
folder). Next, copy the contents of the CM93 folder on CD2 into the CM93 folder on the hard
In openCPN I added the path to the CM93 folder on the hard drive (e.g. C:\C-Map\CM93) to the chart path and the charts came right up. I deleted the paths to my normal raster and vector charts when using CM93 since openCPN seems to bog down pretty bad with all of those charts loaded. That's not really surprising - most commercial
programs would probably start struggling with that many layers of charts.
That was it. CD2 would not work by itself, I think because the .DIC files were not present. Let me know if you need more details about the folder contents.
I spent quite a bit of time playing around with the CM93 chart set and it works great in openCPN. Interestingly, you can spend hours cruising the world zooming way in and out, opening probably hundreds of charts with no change in performance. It's all automatic and pretty much seemless with a couple of exceptions. I have had openCPN crash on me when opening too many ENC charts, but I haven't made it crash with CM93 yet.
The biggest exception I've seen is when getting near 180 degrees latitude, which you said you're already working on fixing. Depending on the chart, getting beyond 160 degrees is flaky, and of course you can't scroll across 180 degrees. Tonga
, which has charts that straddle those points, gets all goofy if you try to zoom in.
The charts themselves vary quite a bit. Any place with a lot of shipping
has great detail. For example, the Torres Strait has as much detail as you can deal with through the shipping
lanes. If there's not a lot of shipping it's a lot more hit and miss. Places like French Polynesia
or Saint Helena island have a lot of detail around major harbors based on English
and French surveys but little detail away from those harbors, while Tonga
has no detail at all (although perhaps the 180 line issues are causing the charts not to load?). The southern California
charts are as good as the latest NOAA ENCs from what I could see. For laughs I entered a few waypoints from SSCA bulletins in places like Fiji
. The Fiji
locations looked right, while the Vanuatu
locations were invariably half a mile inland. That lines up with what I've heard from other people. I'd bet the Marquesas
charts are all off by a mile also.
Your comment about how ENCs are loaded is what I thought it would be, but I'm mostly an embedded programmer (cell phones) and not a Windows app programmer so I didn't want to assume. For now it probably makes the most sense to load only the charts I need, and skip the layers of wide area charts (I don't need the eastern half of the Pacific to get to Catalina) which probably eat up gobs of memory. FYI, I've never really seen openCPN slow down with raster charts.
You guys have done a great job with openCPN so far!