I've been very happy with Charts & Tides, including the excellent ActiveCaptain information. Offshore away from cell signals I keep the phone in airplane mode except for when I'm explicitly looking at Charts & Tides or one of my other GPS/navigation applications. That seems to be a reasonable approach.
I'm hoping that some future upgrade to iOS will give us a way to turn the GPS back on in airplane mode, just as we can currently choose to turn wifi back on in airplane mode.
Is the ActiveCaptain info in the Charts &Tides app loaded or does it require cell connection/ wifi to retrieve info? How precise is the GPS without cell/wifi service?