Thursday, November 12, 2020

Georgetown SC: Rain, River Flooding and Hurricane Eta

We made it under the nine fixed bridges yesterday along the 24 nm of waterway between the Myrtle Beach Yacht Club and Osprey Marina. My vertical clearance calculations were spot on, except for the last bridge where the clearance per the air draft board was only 64 feet versus my estimate of 64.5. However, since the VHF antenna never touched, I think my calculation was the more accurate figure.

We also passed through three swing bridges, the first two without incident, the third requiring us to anchor in the channel for almost an hour to wait for a new bulb to be installed in one of the bridge's traffic lights. There was quite a line of boats behind us by the time the light was fixed and the bridge opened.

We spent the night in the Osprey Marina, a nice facility in a somewhat remote area between Bucksport and Myrtle Beach, a quarter mile down a private side channel off the main waterway. Our dock was so far away from the marina building that we were assigned a golf cart to get to and fro! We also received a welcome bag full of goodies and marina swag, a first for me.

It rained really hard last night, weather from Hurricane Eta making it's way north. Really hard. I haven't experienced a torrential downpour like that since being in Panama. And it rained heavily for a long time, too.

When we left the marina this morning, it was high tide and the waterway looked swollen by rain to me. We had only one fixed bridge to clear near the end of our day's journey, but I was worried that the rain would raise the water surface above the normal conditions on which the tide predictions are based. Also, the bridge was reported to have no air draft boards, so I would not have any actual clearance data when I got there, I would have to go by calculation and general observation.

We entered the Waccamaw River about a mile downstream of the marina. The Waccamaw is reported to among the most favorite rivers in the country for boating and I could see on a sunny day how beautiful it might be, a wide channel lined with broad expanses of cypress wetlands, surely teeming with wildlife. Today, though, it was grey, rainy and generally dreary, with little to see, all the colors muted and drab, all the birds and animals taking shelter.

I couldn't tell if the river looked so full and high just because it was high tide or if there were also a flood flow. I tried finding information about the current river conditions on the internet and learned that the upper reach of the Waccamaw is expected to crest at near flood stage late tonight. That concerned me.

I decided I would drive the boat over spot depth soundings shown on the chart and see how they compared to observed depth as measured by the depth sounder. A half dozen observations later, I concluded that the observed depths were very close to what they should be considering the state of the tide and that the rainfall was not raising the water surface. This was encouraging.

I had timed our arrival at the bridge to coincide with low tide to give us maximum vertical clearance. As we drew closer to the bridge I noticed that the roots at the bases of the cypress trees were exposed and that the water surface was several feet below the high water line on the day mark poles. Also good news.

"Community Notes" on my electronic charts stated that the bridge has 65 feet clearance if the water is just a few inches below the top edge of the fifth board down from the top of the bridge fender. I needed to observe the water to be at or below the top of the fifth board before I would try passing under the bridge. As I got within range to observe the bridge fenders with the binoculars, it started to rain really hard, obscuring any visibility. A strong current was pushing us towards the bridge and, though I knew the engines were powerful enough to overcome it should I need to turn around, it was still a bit nerve-wracking, moving quickly towards the unknown in driving sheets of blinding rain.

Fortunately the rain eased and I was able to make out the bridge fender boards at last. One, two, three, four, five...six boards showing. Whew, what a relief, something slightly more than 66 feet clearance! A bit less than what it should have theoretically been at low tide, so maybe there was a bit of rainfall effect on the river. I proceeded under the bridge, slowly and cautiously at first, then at normal speed as I confirmed we had plenty of room above the mast. What a relief! I celebrated my piloting and navigation victory with a wee dram of rum.

We pulled into the anchorage in front of the steel mill in Georgetown at about 14:00. Quite a few boats are anchored here, so we had be a bit careful about where we chose to drop the hook. The anchor didn't set on the first drop, which hardly ever happens, but I attributed it to the shallow 6.5 foot depth and short chain length even at a 5:1 scope. We dropped again and backed down long and hard with the engines to make sure the anchor was set, then finally got out of the rain and relaxed for the rest of the afternoon. 

The day's drama was not over, though.

Since we have been sailing inland waters, I have been following the land weather forecasts more closely than the marine ones. The land forecasts make only passing reference to Hurricane Zeta and only in terms of rainfall. The marine forecasts mention the hurricane incidentally in the synopsis, but nothing of special note. And I stopped checking the National Hurricane Center reports when I read that Zeta was heading into the Gulf of Mexico. That was a mistake.

The hurricane just passed right by us not far offshore from the coast!

Around 19:00 this evening, the wind started blowing really hard, mid-20's to 30 knots. A boat downwind of us flashed a light at us and yelled across the water, "Are you dragging?" It was difficult for me to fix our position in the darkness. I didn't think we had dragged anchor because our position relative to the boat to our port was about the same. However, it looked like we might have moved relative to the three other boats nearby. I switched on the chartplotter and, lo and behold, we had dragged about 400 feet! The first time Intermezzo's Rocna anchor has ever dragged and quite a surprise to me, given how hard we backed down on it when we dropped. The boat next to us was dragging, too, thus my initial confusion.

We fired up the engines and Lisa did a fantastic job driving the boat in 30-plus knot winds and driving rain while I handled the ground tackle up on the bow. We motored back close to where we originally anchored and dropped the Rocna again, this time with an additional 25 feet of chain, 100 feet total in 10 feet of water.

I set an anchor drag alarm and placed a waypoint at the boat's location on the chartplotter so I could monitor our movements. We seemed to be set pretty well, but we did trip the drag alarm once, our position shifting by about 90 feet downwind. The wind is veering us around quite a bit and I'm thinking that the anchor is getting tripped up a bit in the shallow water as we move from side-to-side. We haven't moved since, so I'm hoping that the anchor has dug itself into the hard mud bottom for the night.

Fortunately, I can monitor all this from inside the comfort of the cabin with my iPad repeating the chartplotter display at the helm. I'll be sleeping in the salon tonight so that I can keep watch and hear the drag alarm if it goes off. The winds are supposed to drop a lot as the hurricane has passed by, so I'm not too worried. It won't be a night of uninterrupted sleep, though.

Frankly, I'm tired of these Atlantic coast hurricanes and fronts. So much more frequent and volatile than what I'm used to in the Pacific.