Boat Handling Question - Wind Shadow from Bridge

[kellyima]

I was sailing under a long, large bridge (Tappan Zee Bridge on the Hudson River) the other day and encountered a wind shadow effect where the wind (coming from same direction of length of the bridge) died down considerably and the direction shifted slightly.

I had the choice of either lufting and letting the tidal current carry me through, or catch whatever wind there was but sailing toward a piling. I picked the first, lost headway, and think the light wind overcame the current with the result that I drifted onto the piling anyway.

No big deal, just a slight ding on hull which I can fill in, but I'm just curious if anyone has encountered this situation. I'm thinking my angle was wrong and I should have come into the span at a more oblique angle and further to windward. This way I would not have had to luft and would have had more sea room to fall off, without getting close to the piling.

Has anyone ever hit this situation and could they offer some advice. Nothing like hitting something to confirm you didn't do it right. Oh well, just another sailing adventure!

[jcalvinmarks]

On my second time out (first time single-handing), I had a problem with a bridge. The bridge is very near the dock I was sailing from, so I was drifting over that way to see if the mast would clear. I got close enough to read the numbers on the piling, decided it was too close for comfort, and went to fire up the motor to get away (since the wind was blowing me towards the bridge). But the motor wouldn't fire up. Uh oh! I decided to raise the sails quickly to try to beat away from the bridge, but since I was single-handing, I couldn't do it fast enough. The wind pushed me under the bridge, and to my surprise the mast and even the Windex on top cleared. What a relief!

The northern part of this lake has no boat ramps and is a bald eagle habitat, so I was thrilled to be out there! I sailed around for several hours, rounded a few small islands, practiced tacking, got a feel for heeling in a stiff breeze (maybe 8 - 9 mph), and had a whole lot of fun. Until it was time to head back to the dock. In North Carolina, it seems, the practice for building bridges over man-made lakes is to build long jetties out from both sides, then build a short bridge. The wind is coming straight from the direction of the bridge, and as I get close to the bridge, I realize that it is doing two things: one, it is funneling the wind because of the jetties on either side (which are themselves 25 - 35 feet above the water), and two it is making the wind erratic. Out in the wide open a mile away from the bridge, the wind was relatively steady. But once I got within a few hundred feet of the bridge, I was getting odd shifts, sudden lulls, and winds of probably 12 mph. But since the motor wouldn't work, I really had no choice but to try to tack through this awful wind, and come out the other side (hopefully). I tried several times, and each time I lost steerage because of inconsiderate powerboaters making too much wake in the no-wake zone around the bridge or lulls in the wind, and I'd have to go around, run out, and try to tack back through. On the last attempt, I lost headway to a lull while I was under the bridge, and tried to bear off to port. Unfortunately, I had cleated the mainsheet, so when that 12 mph wind picked back up in a hurry, I had a sail sheeted for a close-hauled tack, with wind coming straight abeam. It heeled me over about 30 degrees, and shot me in a broad reach at about 6 mph right into the jetty, which is covered in rip-rap.

I tried to push the boat off the rocks and get back under sail, but the wind made it very difficult. Finally I took the motor and rudder off the back to keep them from getting damaged on the rocks, accepted a tow from a very nice family in a powerboat, and went back to the dock. I was done for the day at that point.

So I guess the big lesson I learned from all this is that bridges do odd things to the wind, and unless you can go under on a broad reach or in a run, it's probably best to swallow your pride, fire up the motor, and play it safe.

I have since found a lake in Southern Virginia that has almost no bridges in its entire length, except for one which has a 75-foot clearance.