I must confess that after more than 30 years of cruising the South Carolina coastline, I’ve actually only traversed St. Helena Sound’s inlet on two occasions. And, my most recent passage is at least five years old. So, I’m glad Captains Bob and Janet chimed in with the very newsy and useful message below.
St. Helena Sound stretaches seaward from the AICW’s run through the Coosaw River. Often, I’ve seen shrimping trawlers working these waters, and they can be a very angelic sight while cruising along! Clearly, these commecial craft make use of the sound’s inlet, so, with the info below, perhaps cruisers can run this channel as well.

Hi, Claiborne
We never received a reply to our inquiry about the inlet channel through St. Helena Sound (just north of Beaufort, SC, at the mouth of the Coosaw River), but we’re happy to report that we had a very successful cruise through there last month on a several-day excursion from our home port in Beaufort to Charleston. The channel is well marked and was charted accurately on both our ICW chart book and our C-Map NT+ electronic chart of the area, with good water throughout — anywhere from around 12 to 25 feet at more or less mid-tide. The channel does have some tight bends in a couple of spots, so you have to pay attention, or you could find the bottom quickly, even a couple of miles offshore. The only downside to taking this route instead of the ICW route up to Charleston is that, surprisingly to us, running “outside” was longer for us in both distance and time than staying “inside” on the ICW (which we did on our return trip back to Beaufort). This is because you have to go at least 5 or 6 miles offshore to stay clear of shoals, whereas in the ICW, with the dredging that’s been done recently, you can now make very good time without the fear of going aground in mid-channel. We found the recent posts about shoaling to the south side of the intersection of the Dawho and North Edisto Rivers very helpful, and had no problems either there or at the junction of the Coosaw River and Ashepoo-Coosaw Cutoff, which had been a real problem as recently as last year. Hope this helps! Happy cruising.
Bob and Janet S.
M/V Harmony
Beaufort, SC