Make you own charts

Make your own charts from CMAP so you can adjust them, add routes and waypoints, and then print them out. I use CMAP World for Windows, it has a few advantages over CMAP (for chart copies).  You can select a chart scale and then zoom in and out on that specific scale picture, it allows you to see the charts borders used by the underlying software, and it runs in more than 256 colors.  Once you have the general area you are interested in, shift around, zoom in and out until at least two latitude and two longitude lines appear. Use SNAGIT to take a snap shot of the chart; I use the region functionality and I make sure that I capture the side and bottom so that I get the CMAP Lat/Lon of the grid lines on the chart. I save the file as Jpeg to save disk space but if you plan on making any graphical edits save it in bitmap format for clearer editing in Microsoft Paint. Once you have the picture you read it into OziExplorer using the Load/Calibrate Map Image option. Select the image you just created, choose WGS84 for Map Datum and Mercator for Map Projection. Next select Point 1, a cross hair will appear; place it on the chart at one of the lat/long lines you captured. Enter the CMAP lat/long of that point. Do the same thing for Point 2, but make sure you pick the opposite corner of the chart, so that you have a change in both Latitude and Longitude, and then save the chart. Double check to make sure that as you move the cursor around the resulting chart that the latitude and longitude positions given by the cursor make sense, if they don’t make sure you have the correct points (and N/S E/W) entered. You now have the basis of the chart that you can use to calibrate or shift with either local knowledge or Satellite photos. Adjust the chart by using the Check Calibration of map. Oziexplorer has the ability to enter many calibration points, however I typically only use two so that I am just shifting the data (change both Lat/Long by the same value in both calibration points). I figure the cartographer got the local chart mostly correct, but they didn’t have the effective tools to get the exact Lat/Long. If you do more than shift you no longer know how they saw the data while they were creating the chart, who’s to say what local geo reference they used or if there was more than one? You can also create or modify your own charts by using a GPS track to adjust the cmap snapshot in Microsoft paint. You can add motus or bommies that don’t exist or change the shape of the reef by “tracing it” with your dinghy and a handheld GPS. It’s nice to be able to download the crazy track we made in the dinghy into a clean route using Oziexplorer before we enter following our route on the GPS. Remember to use your eyes... the chart is only a guide.

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