Slackwater...you can run two OPCNs at once.
Get into OpenCPN
3.0 as a portable version for best results or your settings won't be saved on shutdown.
Just minimise the Aft one when you are using the forward one...but use the new Version 3.0...2.5 has minimising issues if it's shutdown when minimised.
If you do follow my advice, follow this too:You can avoid the ".bat" stuff by making a shortcut to the opencpn
.exe in the portable folder and simply typing a space then -p
in it's Properties dialogue (it's the so called "Target" field where you add this "-p". It will look like this -it's xp but you should have similar facility: