Coastal areas like Isle of Palms experience two high and two low tides every 24 hours and 50 minutes. High tides occur 12 hours and 25 minutes apart and change every day. For example, high tide could occur at 12pm on your first day and then, again, around 12:50pm the following day and so on.
Isle of Palms is known to have very large tides, so it is not unusual to have the ocean water within a few feet of your equipment at one point during the day and then a hundred yards away a few hours later.