A Tale of Two Chemists: Playing the Tides

Playing the Tides

Thursday 1st - Friday 2nd May, 2025

It’s been a while since we last travelled on the Atlantic Intra Coastal Waterway (ICW). In our 'rose-tinted' memories it was easy, and in part that is true. You mostly don’t have to worry about the sea state and there are plenty of places to stop. But in some areas, South Carolina and Georgia in particular, there are many shallow sections and the navigation is demanding. In our early forays into these areas we had some nail-biting experiences passing through the shoal areas. However, during our Covid trip we learned to play the tides. In the coastal marshes of Georgia there are sections of the ICW, where, because of inadequate dredging, the channels have silted up to less than 4 feet at mean low water. Cotinga has a draft of 6 feet, so obviously that’s a problem. However, the tides in Georgia are about 7 feet, so if you time your travels you can be fairly confident of having enough water.

We left the anchorage off Cumberland island around 9 am, three hours before high tide and travelled 38 statute miles* to an anchorage near St Simons. It took us about six hours and so we never had less than half tide (say + 3.5 feet above mean low water). Similarly today, we departed at 10 am, three hours before high, and travelled 43 miles to an anchorage in the Wahoo River. We passed several notoriously shallow sections, but never saw less than ten feet on our depth sounder. This method makes for fairly relaxing travel, but it does mean that you are limited to a small time window and, of course, it becomes more challenging when the timing of high tide is early in the morning and late in the afternoon.

The other issue is current. With relatively large tides there are strong currents. As you wind your way through the creeks, rivers and estuaries you can have 2 knots of current at one moment pushing you along at 8 knots, then as you turn a corner it can be 2 knots of adverse current limiting you to 4 knots of boat speed. A creek that runs from one sound (estuary) to another will flow can opposite directions at each end. Despite hours of agonizing, it is almost impossible for me to compute detailed expectations of current for a 6 hour passage.

The scenery tends to be wide open marshes with patches of wooded islands. It’s sparse but atmospheric, hard to photograph, particularly in teh middle of the day. In contrast to the Bahamas, the water is dark and brown, but we have seen countless dolphins. There are all sorts of birds including terns, gulls, herons and egrets, shorebirds and osprey. We have also seen several bald eagles. Unfortunately, it’s also quite buggy and we have had swarms of horse flies in the cockpit (thankfully, they don’t seem to be biting). Once anchored we put in our insect screens and the bugs aren’t an issue.

As we came into drop anchor this afternoon the ebbing tide and southerly winds were in opposition. We wondered how that would play out. The answer - the boat lay sideways to the current and the wind, with the anchor chain going back underneath the keel. Go figure!

What I have described is great way of cruising the marshes, but as I mentioned it isn’t fast. One of the challenges we are grappling with is that we are now quite keen to get home and consequently would like to be moving a bit faster. We need to learn to enjoy the moment and not be in such a rush!

* Distances within the ICW are measured in statute rather than nautical miles (about 10% smaller)

Mike

31 35.564 N, 81 12.267 W