First trip I took I almost ran aground on that same sandbar. I was motoring along with an eye on the chartplotter ( which showed we were in plenty of depth) And we ran out of water. Luckily I was on my toes and backed out before we had any trouble. I just assume that the water coming out of longboat shoals it up and the shoals move quite a bit. Needless to say it was an experiance that made me a more cautious Captain.