How to stop a singing mast?

[e31]

At an anchorage over the weekend my mast began to hum from what I assume was the perfect windspeed to get it to ring harmonically. With my hand I could feel the vibration on the mast, and locally on the deck around the mast. The wind was not enough to whistle in the rigging, say around 10kts.

Since it did this from 2am to 6am (as a weather front came through) I would like to understand what I need to do to stop this phenomenom.

Anyone else ever expirience their mast "singing" to them?

[Yodagwb]

How about wrapping a large towel around the mast and hoisting it half way up via a spare halyard. Remember a tag line to get it back down with. That may be enough to change the vibration rate. It may look stupid but after awhile you get use to that. Got nothing to lose.

[e31]

Thanks for the towel idea. The other suggestions I got where:

1) turn and lock the rudder to changer the angle of the wind on the mast

2) loosen or tighten a turnbuckle to change the "tuning" of the mast, although, my luck the wind speed would also change, and I would be up all night "playing" the rig.

3) Wrap the spinnaker halyard multiple time around the mast, disrupting the airflow.

I will try one of these the next time I''m out and am kept awake by my boat''s concert. Sailing with a two year old and three year old, I have found "looking stupid" takes a back seat to functional sanity.

Doug

[pirateofcapeann]

I doubt it''s your mast. It is part of your standing rigging vibrating through to your mast. Try tying on a tag line from the mast to the shrouds and the stays. A little experimenting with the position and tension should do the trick. I my case I use tag lines to keep my halyards from slapping against the mast and they also keep the shrouds from humming. I wish more people would do this as there''s nothing more unnerving then listening to the sounds of the wind whistling through the "aluminum forest" at 3:00 AM!

[wwilson]

Do you have in-mast furling? The slot often responds as you describe.

Wayne

[capttb]

I generally move halyards etc. cause I like the boat quiet at night. The other night I got back to the dock at midnight and spent 45 minutes after I went to bed trying to figure what this intermittant horrible vibration in the rig was. Went up and checked lines etc. a couple times, finally dawned on me that I had left a small flag up on backstay that was vibrating just right during certain wind gusts from the stern. I couldn''t tell where it was coming from I just knew that wire was involved.

[foxglove]

I used to own a small sailboat with a swing centerboard that sang when the tide ran under the boat at a certain speed. The noise telegraphed into the entire boat including the mast. If I cranked up the board, the noise stopped. Could this be it?

[e31]

The keel on my Ericson 31 is fixed, so it was not the centerboard cable...although it is the same problem.

When I put my hand on the mast, I could feel the vibration, and it was nowhere else on the boat (that I could find).

[wwilson]

e31

From a leading spar manufacturers owners manual...
"Vibration can occur in any aluminium mast of normal design. With wind coming from approximately abeam at speeds of 4–12 knots the mast oscillates longitudinally at a rate of 3–6 cycles per second. As an optional item an ”anti-vibration strip” is available for hoisting in the integral sail groove at the aft face of the mast to prevent vibration starting. It will also reduce wind noise."

[SailorMitch]

I had this problem with my last boat, and it turned out to be pulling the mainsheet too tight for the topping lift when not sailing. Eased the mainsheet a tiny bit and the vibration noise disappeared. I applied the same cure to a friend''s boat who was amazed the cure was so simple. Obviously may not work for others, but it''s a simple thing to check on to see if it works.