singing rigging

[dbb]

I just bought a 20' Goman Express that is named the "Bailero". which is the name of a French folk song. There is a passage in the song done by a single flute which sounds almost like the whistling that my boat produces when enough wind is blowing across the mast and rigging. Multiable notes
at the same time fluctuating with wind velocity.

I paid for a years moorage at a local campground/rv/marina resort and moved the boat in last Wednesday, this morning the manager phoned and complained that my boat made a bunch of noise that she described as haunting. She said when the wind got up it was very loud and could be heard from all over the resort.

I have no idea what is making the noise but it sounds like I'm going to have to do something about it or find a new place to keep her.

Anyone ran into this problem before? Any suggestions?

[Siamese]

It's haunted.

Heck, I don't know. There's a 56 foot ketch on my dock that sings with every moderate breeze. I wish he'd tow it away and scuttle it.

[VK540]

If your rigging is tuned properly and it still persists than perhaps this website can help?

The Stay Quiet - Vibration Dampening

[killarney_sailor]

Does your mast have a slot that the mainsail slides up? If so, the sound could be coming when the wind flows across the slot. Happens with my Bristol at times (wind from quarter). The boat actually came with a 'flute-stopper', the sailmaker's name for it, not mine. It is strip of stiff sailcloth about 6" wide with a large plastic 'button' pop-riveted on about 3 feet. You hoist it up the mast with the main halyard with the cloth inside the mast and the buttons riding up the outside. If your mast slot is the problem you could make a smaller version that would fit your mast.

[Faster]

We have a Dyneema backstay that thrums loudly when fully tensioned in a breeze. Easing tension quietens it. Perhaps you might check rig tension.... if you have an adjustable backstay ensure it's slackened at the dock. Your boat will thank you for it.

[dbb]

thanks for the tips guys,

I know the previous owner raced her and the shrouds feel singing tight
(he, he)
so until I can get a loo guage to set them I'll try just loosening them a few turns. Evenly of course.

[Liquorice]

Try turning the boat around - see if that makes any difference!

[Minnewaska]

Oddly enough, my rig resonates loudly at anchor (bow into wind) if the boom is cranked down too hard. I take a bit of tension off the mainsheet and it stops completely.

[RichH]

What is going on is whats known as an 'induced harmonic vibration response' in the rigging or mast system. This is what makes a violin or cello, etc. string vibrate. The Rigging or a mast (or combo of both) is being 'excited' by wind conditions flowing over or around the rigging/mast ... and is producing a sound that is 'harmonic' to the 'energy, etc. conditions' of the wind.

Such vibrations are dependent on two things: rig tension and the mass of the wire/rigging. If you change the tension or the mass (by simply 'hanging' some weight in the rigging) you will either change the 'note being played' or will arrive at a vibratory condition where there is no harmonic response; Rx: change the tension or hang a weight onto the 'wire thats vibrating'.
For a mast that is 'pumping' or radically vibrating, add the proper 'prebend' to the mast by correct rig tension - typically 3/4" forward bow to a single spreader rig or 3/4" forward bow per each spreader set on a multi spreader rig --- the mast manufacturers all have specific 'pre-bend' specifications on each mast section offered. Using a mast without 'prebend' is an open invitation to 'mast pumping' / radical induced harmonic vibrations (and your mainsail was cut to match that expected 'pre-bend'; without that pre-bend the mainsail will always be slightly 'powered-up'). Adding 'pre-bend' changes the 'apparent stiffness' of the mast and changes the 'natural frequency' at which the mast vibrates.

To find the part of the rig that is the 'culprit', when the 'note is being played' simple go to each component and with your hand & 'feel' the part that is 'buzzing' and affect the correction (tension or weight change). If you cant 'feel' the errant vibration, borrow a vibratory tuning gage from a stringed instrument musician and when the gage shows a B#, etc. ... thats the wire that needs 're-tuning' --- just re-tension up or down until the harmonic ceases (but may issue another 'note' when the conditions are correct for that new tension).
In cases of severe 'harmonic response' (mast pumping) where the mast is actively and noticeably 'rocking back and forth' (can be 'violent' rocking/bowing), especially in high wind conditions ... this must be quickly corrected as such high energy harmonic vibrations can soon cause mast / rigging FAILURE (the classic example of destruction due to 'harmonics' is the failure of the Tacoma Narrows bridge in the late 1930s). The quickest emergency remedy is to pull the wire or mast with a rope attached or tied to it and pulled at a perpendicular angle and led to a winch, etc.

However if you have an in-mast furler (acting like a 'flute' with air flowing across the slot and producing the 'note') then the only way to solve this is cover the 'slot' by any means possible - raising a 'twisted or 3 stand 'rope' in very close proximity to the 'throat of the slot', etc. ... anything to disturb the air flow 'across' the open slot, or closing the slot.

:-)

[mxracer19]

I second RichH's post. Hoist a piece of line up the inside of the boltrope track roughly the same diameter as the boltrope on your mains'l to silence the "flute-ness" of your mast. If that doesn't work, try tieing a small piece of line to the different wires of your standing rigging. When the boat sings, pull the lines until you find the culprit. Tugging on the line will tention the wire and dampen the resonance.

-Matt