Folkboat with creaking noise in high winds.

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Folkboat Dave

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I am getting a strong vibration on either tack in 15-20 knot winds. Feel the vibration must right under my seat in front of cockpit. Less so when I am at the tiller.

Anyone have the same experience? Wondering what the source could be? Rather concerned
 
Wear between the pintle and gudgeon, allowing the rudder to vibrate perhaps, or is the prop turning?
And welcome of course.
Next 'requirement' are pics and details I'm afraid.......:)
 
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Have you re-tensioned the rig? Some years ago, having re-stepped the mast after winter lay up my boat started 'singing' in fresh conditions, but only audible in the galley/chart table area below the hatch.
On the boats I have sailed a prop turning tends to be a low frequency rumble, usually more audible below decks.
 
It could be vortex shedding from the rigging.

To check, you need to wind thin cord round and round each shroud or stay in turn. The cord prevents/reduces the vortices from causing the wire to vibrate. Vortices can also be controlled by changing shroud tension, or flow blockers (small 'blobs') about the size of a walnut screwed to the shroud. Such devices are frequently seen on cable stay bridges like Severn Crossing 2.
 
My dad bought a new Halcyon 27 and had this awful thrumming noiseThe riggers nor the builders could shed light on the noise.On a weekend trip I did he offered ten quid to anybody who could solve the problem.Lying down on the bunk it came to me,the boom was tensioned down with the main sheet and tensioning the topping lift,leaping up he freed off the main sheet and peace reigned........never got my ten quid!
 
Thanks all for your suggestions please keep them coming. I forgot to mention this is a 1972 International Folkboat made in Sweden sailed hard at times in San Francisco Bay. Vibration is felt most right under where you sit in the cockpit forward of the traveler, near the cabin hatch on either tack.
 
Is she moored right now, or lifted out between races/weekends? That'd be easy to check my rudder theory, or if not it's going to be easy enough to check the rigging stuff I guess. Am I right in thinking that your boat doesn't come with an inboard engine?
 
jamie N said:
Is she moored right now, or lifted out between races/weekends? That'd be easy to check my rudder theory, or if not it's going to be easy enough to check the rigging stuff I guess. Am I right in thinking that your boat doesn't come with an inboard engine?
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Yes, correct. It has an outboard
 
Well, that eliminates one of my ideas! Being where you are, winds are frequently that strong, which makes your boat so perfect for it. If it doesn't happen going downwind, then it probably is a resonance in/on the rigging caused by the wind. As others have said, I'd try (perhaps) just putting a length of bungee between the upper and lower shrouds to disrupt the frequency. Costs nothing, and might indicate further where it is. Are you sailing this weekend?
 
So it's not a spinning prop, the rudder looks unlikely because you'd feel it through the tiller, I can't imagine that the lee shrouds on a Folkboat would be tight enough to vibrate like that, and the forestay and windward shrouds would be too tight. Backstay - can't imagine it? Jib/main leech fluttering, but you'd see/hear that? Something snagged around the keel or hanging out of a skin fitting?

Can you give us an idea of the frequency? (there are 'phone apps...).
 
Got to disagree with you here I'm afraid. My rudder pintle bushing was quite worn on the foot of the rudder, and did make a similar/different vibe in certain conditions without feeling anything specifically through the tiller. Of course, the OP's might well be different. I made a new bush and it did eliminate the issue.
 
jamie N said:
Got to disagree with you here I'm afraid. My rudder pintle bushing was quite worn on the foot of the rudder, and did make a similar/different vibe in certain conditions without feeling anything specifically through the tiller. Of course, the OP's might well be different. I made a new bush and it did eliminate the issue.
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Fair enough - I'll know what to look for if mine goes!
 
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