There is a 5 foot shallow spot in the ICW about 0.3 miles south of G117A near Sullivans Island, SC. Heading south last November we found the shoal and marked it on our charts. 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 MLLW (Mean Lower 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 at least 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.