OpenSeaMap.org how-to guide
How to get OpenSeaMap charts into MacENCx64
OpenSeaMap (www.openseamap.org) is an open source, worldwide project to create a free nautical chart. There is a great need for freely accessible maps for navigation purposes, so in 2009, OpenSeaMap came into life. The goal of OpenSeaMap is to record interesting and useful nautical information for the sailor which is then incorporated into a free map of the world. This includes beacons, buoys and other navigation aids as well as port information, repair shops and chandleries. OpenSeaMap is a subproject of OpenStreetMap and uses its database.
Navigating to the site and selecting download charts
Go to www.openseamap.org
On the left navigation sidebar, just inside the Nautical Chart box, choose “Download chart”
Scroll to the bottom of that page, and select “Download-Layer for KAP-Charts”
On the left of the chart map, you will see Download Type and a selection box. Make sure you pick KAP as the type.
On the map of charts you will see highlighted sections. Select on of those areas you need and that will show up on the left navigation bar with the download item details. That archive will contain all charts in the selected area zipped up. Choose download to get the chart files.
For this how-to, we’ll choose the Medi-West charts. Note in the image below that the section is highlighted, and the left side shows the chart name the format type of KAP and the download link.
Managing & unpacking the chart download
Our download folder (or where ever your browser puts downloads) will have the resulting chart archive. Navigate there.
The Open Sea Maps are zipped in 7z format. You’ll need an app to open that. The Mac App store has “The Unarchiver” app which works nicely. Here is a link https://apps.apple.com/us/app/the-unarchiver/id425424353?mt=12
Once the Unarchiver (or equivalent app) is installed, you can double click to unpack the archive. You’ll now have a folder with chart contents alongside the archive. You can do this right in your downloads folder if you wish.
Preparing and moving to your charts folder
Next, go to your Charts directory. Where this is depends on how you set things up originally (especially if you had the original MacENC). For me, I keep mine in Documents in a folder named Charts
Beneath that I have a folder ENC (for that type of chart) and RNC for those.
OpenSeaMaps are RNC’s so I would want those folders beneath RNC. I always name my actual chart folders descriptively based on the area of coverage. You can do that in one shot.
Have your Charts/RNC folder open and your Downloads open.
Then drag the folders you unpacked from downloads over into RNC. If you don’t like the folder names as they come from OpenSeaMaps, you can rename them. I named mine: OSM-MediWest.
Inside that folder you will see the *.KAP files which are the charts.
Add the charts to MacENCx64 with Chart Manager
You are now ready to tell MacENC about your new charts. Open MacENCx64. Select File=>Chart Manager
Click the [Add Chart Folder…] button. A finder window will pop up and you will navigate to your chart folders all the way down to your newly created one. Select that and click the [Add Folder] button.
That will add the folder which you will now see in your chart catalog. It will default to Show=ON and you will see the individual charts beneath the folder.
Close Chart Manager and Navigate to the region of your new charts.
Viewing Raster Charts (RNCs)
OpenSeaMap KAP file charts are Raster charts so you will need to set the View. Once over the geographical region of the charts, select View=>Raster Chart (or press command + R on the keyboard).
Voila! The charts will render.
Remember to use chart manager (Show=On or Off) to keep just those areas ON that you need for that session. Loading up the whole world will just slow you down.