Here's an app not for privacy buffs - but which parents or spouses might find useful for boating. The GPS Tracking Pro (Life 360) app for Android and iOS, when installed on two or more smartphones, lets the other(s) see where you are on Google Maps if you or they sail (or hike, or drive, whatever) out of sight. It also makes it easy to check in or contact others in your circle. While your kids might not like you knowing where they are at all times that their phone is on, in some situations this could be an important safety consideration. Read a review here of how it works.
