Humming/whining noise from the mast

[Julian and Karen]

This year our Baycruiser 23 has developed a much louder and more persistent whining noise that changes pitch as the wind/boat swings. Initially we thought this was the halyards so we moved them away from the mast and changed the tension but this made no difference. We then tried a cover for the forestay and a rope up the inside of the main track - no difference. We took the mast down to see if it was the wires for the vhf and the masthead light being too loose, we tightened them - no difference. My current thinking is that it is the windex/antenna which I can see vibrating but is this cause or effect  - has anyone experienced this?

[Martijn]

Are you sure it's the mast, not the shrouds?

[Julian and Karen]

We cannot be 100% sure - we also tried connecting the spinnaker halyard to the bow roller and taking the tension off the forestay – this did not stop the humming. From this we thought it was probably not one of the stays – as the forestay has the longest run without contact (the shrouds have the spreaders) and would therefore be most likely to vibrate. Our next attempt to stop it will probably be a change to the aerial (pointing it downwards without the Windex), unless anyone can recommend a different strategy.

[Graham W]

It's probably not relevant but the main source of humming in the wind on my BR20 is from the topping lift - both sides. Searching on Google shows that it's the same for many other types of boat.  I haven't tried it yet but apparently the way to silence it is to release tension on the mainsheet so that the topping lift slackens a bit.  Then the next noise will be the boom banging against the mizzen....

The Windex was also mentioned in passing as a possible source of noise but I couldn't see a remedy.

[Matthew P]

Might vibration from the Windex, or aerial, be amplified by the mast?  If so, changing the natural frequency of the mast or aerial might fix it - or make it at least hum a different tune.

Matthew
BR20 Gladys 

[Graham W]

Put some rubber sheet between the Windex and its mounting point on the mast?