On a lot of boats with a roller-furling foil, and particularly with no sail rolled on it, the headstay will start to pump once the wind gets up, sometimes to the point it gets quite alarming.
Not only that, all that pumping can do real damage to the rig if left long enough.
But there’s a hack that stops it every time, at least for a boat swinging to the wind on a mooring or anchor.
Set up a spinnaker halyard just forward of the headstay as shown in the shot above. That’s it? Yup.
I guess the halyard causes turbulence that breaks up the laminar flow on the headstay foil…or something.
Anyway, we have been doing this for years and it works.
Thanks to Deborah Shapiro and Rolf Bjelke, as I read the tip years ago in one of their excellent books.
The pumping is caused by vortex-induced vibration. If the sail is down, you can also prevent it by simply wrapping the job halyard around the head foil.
You can see the same “engineered” solution on industrial smoke stacks with helical fins/strakes running down them, and even on older automotive whip antennas with a spiral rib.
Hi Jeff,
That makes sense, thanks.
Hi, John. Would this work for a boat in a fixed position? Just about to pull the boat out for 6 months and I am quite concerned about the headstay pumping. The Baltic winter storms can be ferocious. I guess Jeff’s solution is better in thus case (but I assume he meant jib rather than job)? Any other hints on this subject?
Hi Michael,
Probably not, but I’m guessing that Jeff’s solution would, although I have never tried it because I pretty much always unstep the mast when I store a boat. More here on why: https://www.morganscloud.com/2014/11/01/the-dangers-of-storing-with-the-mast-stepped/
Thanks, John. I had indeed read your comments on taking the mast off (I have read everything on your site multiple times since I recently joined). But due to the global economy tanking, I need to keep the costs as low as possible. I even considered leaving it the water but decided against it due to the possibilty of the sea freezing. I will try Jeff’s solution.