I know you have to be careful about calibrating around metal objects etc, my question is, is it ok to fly over marinas and boats (obviously at a safe height) as i have read stories about the compass getting interference near large metal structures etc leading to problems. If it is ok, what would you suggest is a good altitude bearing in mind i dont want to be to high away as the nearer you can get the better the video but i also dont want to be reckless and possibly lose my p3.