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Inching through shallows on ICW

Jan 1, 2003
From Ocean Navigator #120 March/April 2002

From Ocean Navigator #120 March/April 2002

All inland waters with weak tidal flow, narrow rivers or landlocked areas can experience wild fluctuations of water levels associated with sudden changes of barometric pressure and prolonged winds from one direction. On the East Coast of the U. S. you will find this phenomenon in parts of Delaware Bay, Chesapeake Bay and the Intracoastal Waterway. When strong southerly or northerly winds keep blowing, watch your depthsounder, because chart soundings may diminish significantly.

Charted depths may be off by 2 or 3 feet when winds blow steadily from one direction on the ICW. The authors were restricted from certian anchorages despite their boat's draft of just 5.5 feet.
   Image Credit: Tom Zydler

In November 2001 we found out just how low water levels can drop when, due to inclement weather on the passage from Newport, R.I., we decided to continue southward inside the ICW. South of Norfolk, Va., and after leaving Great Bridge, in Chesapeake, Va., we planned to anchor at the recommended anchorage by Pungo Ferry Bridge at marker No. 42 (Mile 28.5) in Virginia Beach, Va. (All Miles refer to statute miles, as is the custom on the ICW, which ascend — as one moves south — from Mile 0 at Norfolk.) However, the 25-knot northerly that arrived the previous night blew the water away, exposing the shores of this narrow stretch. Charted depths dropped by 2 or 3 feet, and our prospective anchorage had 4 feet at the most. With the darkness coming, we anchored our yawl, which draws 5.5 feet, on the edge of the channel, adding the stern anchor to keep from swinging into the path of towboats with barges. Pungo Ferry Marina, which was nearby, had a deep-water outer dock but could only accommodate about two 60-footers. The lesson here: During prolonged northerly winds, yachts that have passed through Great Bridge should allow enough time to reach the facilities in Coinjock, N.C., 38 statute miles to the south.

žTo avoid encountering various obstacles and heavy traffic in the main course of the ICW after the Albermarle⁄Chesapeake Canal, we headed into Pamlico Sound. Mollymawk’s moderate mast height allowed us to make it (just) under the 45-foot bridge to Roanoke Island, N.C., and to make a fast sailing passage to Oriental, N.C. The next northerly arrived the following day and let us make another sail, uninterrupted by any bridges, to Beaufort, N.C. From there we went straight out into the Atlantic.

After 25 hours of a blissful, downwind sleigh ride, the rising northeaster and an unpleasant forecast persuaded us to head into Winyah Bay, S.C. Next day we hoisted our mainsail, boomed out the genoa and had an uninterrupted run of 58 nm to the Ben Sawyýr swing bridge above Charleston, S.C., at Mile 462.2. Here we learned that strong winds also affect the operations of swing bridges. The bridge keeper had to keep us waiting until a lull came in the 25-knot breeze. Fortunately we already bypassed another swing bridge that couldn’t open in winds over 30 knots — on Alligator River, in North Carolina, at Mile 84.2. The lesson again: Yachts on the ICW should allow for delays and unexpected stops.

In parts of the ICW that are subject to pronounced tides, another problem arises that is not indicated by the charts. In many places the vicinity of ocean inlets causes colliding currents to meet each other. When the waterflow slows down, suspended sediment sinks. The old term for it was dividings. The dividings areas silt faster than the Corps of Engineers can dredge. The area where Wadmalaw River meets North Edisto River in South Carolina (around Mile 497) is a good example. At low-water⁄spring tides you should approach close to the shore of White Point before turning into a marked, winding channel and count on having only 5.5 feet of water then. South of Hilton Head Island, S.C., where Fields Cut joins the Savannah River (Mile 575.5), you will find only 4 feet at low-water⁄spring tides unless the Corps recently dredged. In the convoluted tidal creeks of Georgia, we watch for shoaling at Mile 602 in Hell’s Gate by Raccoon Key. Also, we watched our tides at Mile 642 and Creighton Narrows, at Mile 655 and Little Mud River, and then again at Mile 683 on Jekyll Creek between markers No. 17 and No. 20. In Florida, mind your tides off Matanzas Inlet, about Mile 792, south of marker No. 81. More of these areas exist farther south, but we usually avoid the ICW there and get out in the ocean via the St. Augustine Inlet. When exiting there, it helps to have fairly calm seas outside and preferably a rising tide, since the inlet may have as little as 9 feet on the bar at low water.

We keep our tide tables handy between South Carolina and north Florida; the considerable tidal range there certainly helps negotiate the shallow bumps. The strong tides also create some fierce currents in constricted channels. In one such place, Elliott Cut, just south of Charleston, the ebb current often reaches 3 knots. Turn your VHF to channel 13 to hear securité calls from towboats pushing huge fuel barges, a frequent occurrence here. When the current rushes at its strongest, there will not be enough room for both of you in this channel.

Farther south in Florida, near Pompano⁄Deerfield at Mile 745 and the fixed Atlantic Boulevard Bridge, you may, at spring tides, encounter an ebbing current of over 4 knots. A busy barge terminal and a sharp bend in the channel makes this a hairy place. In case you have to wait for the current to ease, you will find a deep and comfortable anchorage in the creek on the east side of the ICW just south of marker No. 17 and about a quarter-mile north of the bridge.Tom Zydler

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