But you're not wrong
Indian ocean files remove a lot of Atlantic shipping for load time purposes, if however you're going to do the full tour, starting out in France, sailing to Penang via a Milkcow, you might want to use the full campaign file instead.
If your PC is half decent the load time of the full campaign is not really an issue.
Be aware, the Indian Ocean does still have plenty of nasty Allies to wreck your day...
also, as always, read the manual, it's worth it
