I'm a new Excalibur user, just got the unit 3 weeks ago... Got an question for other Excalibur users... seems when I have the coil underwater and sweep fast, sometimes a false signal will sound. If I tweak the sensitivity levels, it tends to lessen. Is this normal for the excalibur? Plus, seems that I have to keep tweaking the sentivity levels every few minutes to keep the unit from talking too much... Is this normal as well? I'm hunting on beaches in South Florida, from Delray to Deerfield, sand is all about the same on these beaches.