There is a 5 foot shallow spot in the ICW about 0.3 miles south of G117A near Sullivans Island . Heading south last November we found the shoal and marked it. Coming north March 28, I was looking for it to get an update. I was proceeding at about 4 knots because the state of the tide was 0.1 foot below dead low water, and we draw 4.5 feet. A sailboat from Maine was catching up to me. I called him on the VHF to let him know there was a shoal ahead. He said he was well aware of it. He had been through here before. It always gets shallow there, bla, bla, bla, etc. Anyway, as I come up to the shoal, my chart indicates that a move to starboard will keep me in 8 feet of water and I’ll miss the shoal. As I moved to starboard, the other boat saw his opening and made his move. If I was going 4kt, then he must have been going 6 when he hit that shoal not 2 boat lengths in front of me and came to a stop. He draws 5’3”. So, anyone going through the ICW near Sullivans island mark you charts with a waypoint at 3247.107 N and 079 48.825W. There is a 5-foot shoal there. It as blue bottom paint marking it now.