The pioneers of satellite image navigation such as Sherry & Dave McCampbell of S/v Soggy Paws, and the Hacking Family on s/v Ocelot have taught many sailors how to create satellite imagery and use it for navigation.
Often the computers they used were Windows, not Macs, and they used KAP files, not MBTiles (also known as XYZ files) which are much better.
With some dramatic recent improvements, I thought I would put together a simple-to-follow instruction list for people using a MacBook Pro, and access to fast internet. I am using MacOS Ventura 13.3.1 and planning a trip to Fiji. People with different OS and destinations will hopefully be able to adapt the principles.
1) Download OpenCPN. Use the latest Stable Release. On Nov 1, 2023 this was 5.8.4. The file is 55.0MB. You need OpenCPN 5 or better to use MBTiles.
2) Wriggle round the security restraints on the Mac.
Go to System Settings/Privacy & Security and click 'Open Anyway'.
When OpenCPN opens, it looks pretty bland. We now have to set up the ability to add some charts.
3) Open the Finder.
Create a folder fairly high up, perhaps called 'Charts'.
I believe (possibly wrongly) that OpenCPN is more robust if you keep things as simple as possible. Some people load up their chart folder with lots of charts, and import them into the OpenCPN database. When things go wrong, a common cause is a corrupt chart. It is much easier to sort it out if you only have a few charts in the folder and database.
'When in Rome, just use 'Roman charts'.
Keep all the charts you are not actively using on an external hard drive, and port them across when you are actually likely to need them.
4) Find and download charts for the area you are interested in. Choose MBTiles (aka XYZ files), not KAP files.
KAP files are the older system. They are smaller, but only have one zoom level. XYZ files contain multiple zoom layers, up to about 18.
There are a number of places on the internet where you can find free XYZ files.
Notice that the Chart Locker also has MBTiles for the east coast of Australia.
As you can see, they are seriously large files, so should be downloaded when you have a good internet connection.
I am so impressed with the ArcGIS file, if you are data-challenged I recommend you just get that and the Navionics file. There is a good case for getting all the versions that you can, as sometimes one image is obscured by cloud, whereas another is clear. It is then helpful to switch from ArcGIS to BingSat, or GoogleSat.
After downloading them onto an external hard drive, unzip them.
5) Copy the chart file into your Chart folder.
If you want, do the same with the Navionics, the BingSat and the GoogleSat files.
6) Import them into the OpenCPN program.
Choose 'Charts' and 'Add Directory'.
Next find the Charts folder on your computer.
Back in OpenCPN you should be able to find:
Force a Full Database Rebuild and click Apply and OK
Zoom and pan to find Fiji, and you should see this.
Next zoom right in and be impressed with the quality!
6) Get the GPS working. I am less confident about this stage of the exercise.
The settings are sometimes automatically installed when you plug in a GPS puck. The controls are found in the 'Connections' panel of the OpenCPN Options area.
My MacBook Pro has four USB-C sockets. For reasons I don't understand, the GPS only worked with the back left socket, and not the others. It also worked with a Baudrate of 4800, but not 9600.
Then look in the Connections area of OpenCPN's Options.
I came across one problem; the image of the boat appeared to be a memory of a previous occasion. By going to the Bluetooth area on the laptop and telling it to 'Forget this Device' and then re-contacting it, the image of the boat became live.
I recommend finding a chart that covers your actual location when you are setting the system up, and making sure that the cursor really does correspond to reality before you trust it.
PS. If you can't find a source of MBTiles that you can download for the area you want, this video shows you how you can create your own.
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