There was an obscure note on the chart that we overlooked. It needs bells and whistles because it caused some chagrin. Transiting local shoreline routes are challenging due to shallower water and obstructions. Our Washington DC back to NC trip just completed was roughly 450 miles of mostly Atlantic Intracoastal Waterway (ICW) so I guess we were fortunate that we escaped [most of] the unseen. The ICW is supposed to be maintained to a nominal depth of at least 12′ at low tide. Talmid requires 6′.  Satellite view of the Masonboro Sound on the New River – Cape Fear River
…and the NOAA chart presentation  – same locale

The dashed lines indicate the charted bounds of the ICW. Here is a closeup of the chart and observe the notice that we found pertinent which reads Shl to 5 ft 2016.

Translated: Shoal to 5 feet and dated last year. Ordinarily this would not be a problem area at high tide and I’d been through here twice before but at low water our deep keel found it — and we slid to an abrupt halt.

Worth mentioning is that the inland water is murky dark. Your eye can’t tell if it’s 2′ or 20′. There is a depth transducer onboard which gives us a digital indication of actual depth. We have a aural warning alert set to 10′ to get our attention should depth become a concern. In this instance it did give alert but the depth readout quickly went to 8′ and then just as fast I saw 4.6′ with no time to react. Stuck.

Pure sand bottom, so damage only to my ego. We were able to use reverse propeller at max RPM to extricate and not have to wait for the water to rise. After the fact, and back at my desk, I downloaded this Hydrographic Survey from the Army Corp of Engineers and one can clearly see the issue. The image below is the satellite view with the survey overlay.…and the relevant closeup section (just North of green lateral daymark #135)

Blue is 15+ deep water. Red = bad; and must be avoided. Ordinarily you keep the boat between the channel markers and you should be okay.  From the comfort of my armchair I can see that the preferred and ONLY route through favors the one side.

A published guide book might prove useful as no doubt there have been many gone before that made the goof. I can now say that I have first hand [local] knowledge.