Behind Mast Furler

[artfem2]

I have a Harken "0" furler set behind my mast to furl the main on my 1988 Catalina 30 Tall Rig. When the sail is furled and the wind gets above 15-17 knots, the furled sail and furler begin to oscillate, sending a constant vibration throughout the boat. I think I understand why it happens, the air moving past the slot between the mast and the furled sail hits the resonant frequency of the furled sail and it begins to oscillate. The oscilations translate into vibrations that can be felt throughout the rig and the boat. The vibrations are not only disturbing to the peace and calm I go to my boat for, they can't be good in general for the health of the boat. In speaking with Harken, they say to tighten the system as much as possible (which I have done) but they know of no way to get rid of the problem. I have applied a cinch (a few turns of rope) as high up as I can reach and this has helped a bit. It now takes 18-20 kts. to get the rigging humming. Anyone with experience with this problem, or some deeper thoughts on the cause? Short of mounting a monster tuning fork set to the right frequency to cancel the present resonant frequency, has anyone successfully stopped the oscillation? As always, thanks for your anticipated responses. Art Femenella

 

[Lee Bar 30trailer]

One idea maybe to add into old boltrope slot

add a small part of a old mainsail luff (only a few in.wide but as high as a old main,like flag on the back of mast to guide air flow so it just dose not start oscillation,by keeping air from moving inbetween furler and mast???A sailmaker could take my idea here and maake a custom "V" going from boltrope slot out to each side of furler,made so it dose not get rolled into,but rides on rolled sail,that way it could be lift up all the time.This is only my ideas here,I have not tryed it,as I don't have a mast furler,but if it works call it a Barlow V.Have fun ,lets see what other ideas you get?DanaDragon Wing,Mega 30'

 

[Augie Byllott]

Oscillating mainsail

If you have a spare jib halyard on your '88 as I have on my '78, why not try wrapping it around the mast/furled sail just below the spreaders and continue to wrap it the rest of the way down. You may get the effect of "cinching", but beginning further up the mast than you are now able to reach.