Thank you, Edouard.
I don't intend to migrate wholesale to the new mac using Time Machine (I actually already have the other Mac up and running, and have had for a while. I just want to re-purpose it to weather logging duties).
Now if I understand this correctly, WeatherCat 2 need never come into the equation. I simply...
Disconnect the Davis from the Mac (this feels like major willpower will be required!), and let the datalogger start doing its thing (the intervals and capacity are ok).
follow the instructions for migrating data:
https://wiki.trixology.com/index.php?title=Moving_a_WeatherCat_installation_from_one_computer_to_anotherThen, once that data is on the new mac, download and install WeatherCat 3, which should open and sort everything out. Though it won't see the Davis at this point as it is happily logging standalone.
Then make sure the correct silicone labs driver is installed on the new mac.
Connect the Davis and away we go, logger download an' all?
Will I need to re-enter the station details (lat, long, elevation etc.) or is that all contained in the data I migrated above.
Also, I'm presuming I could download the WeatherCat 3 app on a trial basis and actually test this out on the new Mac without interrupting or otherwise touching the old mac at all. Then when happy, get the Davis moved over and purchase the license.
May I also just take this moment to thank the creators of WeatherCat and all those who provide support on here. I have needed to ask questions rarely as WeatherCat is so stable it just works for years on end with no real input from me. The downside to this stability is that I can't remember what I did years ago to set it up the first time!
EG