Rick McCowan of Mattapoisett, Massachusetts, asks:
"My boat has rod rigging. Whenever the wind blows between about 9 and 13 knots, the rigging hums quite loudly and it’s a bit annoying. Why is this happening, and what’s the best way to stop it?"
Win Fowler replies:
Although I need to know more about your rig to say for sure, I do have some general ideas on how to solve this problem. First, I suspect that the hum is caused by the oscillating turbulence that naturally occurs whenever air flows past the rigging. This is the same turbulence that makes a flag flap in the wind, but with rod rigging it takes place at a far more rapid pace. I suspect your hum coincides with a natural harmonic frequency in a section of your rigging.
Try to isolate the section, or sections, of rod that seem to be generating the noise. Often just adjusting the rig tension, like re-tuning a guitar string, will change the harmonics enough to eliminate the problem. You can also try wrapping a length of tape several feet from the end of the offending rod, or rods. This will change the effective length of the noisy section—much like pushing a guitar string down on a fret.
It wouldn’t surprise me if your shrouds are a little tighter than necessary. When you are sailing fully powered up to windward, your rig should be tensioned so that, with the mast athwartships and in column, the leeward shrouds are just barely tight. If you loosen one of them by just a single turn, it will start to move around. Making sure your rig is properly tuned might result in a quieter rig that also works more efficiently.