Originally Posted by AKFish
I didn't think that selective availability would effect me but it looks like my biggest concern with this tech has appeared.
I believe that SA has been turned off, but would no doubt be reactivated in time of emergency. And it is probably tested periodically, although I leave my plotter running 24/7 and my boat's position is very stable, so the signal can't be degraded very often.
Moreover, the SC doesn't depend on absolute accuracy to determine heading.