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whole-boat shudder

Category: Technical Help
Forum Name: External Fixtures and Fittings
Forum Discription: Questions about external fixtures and fittings (pulpit, deckgear, handrails, etc)
Printed Date: 20 Mar 2019 at 1:48pm

Topic: whole-boat shudder
Posted By: Tazling
Subject: whole-boat shudder
Date Posted: 28 Jul 2013 at 9:54pm
So I've just had a lovely couple of weeks getting to know my Co32 in various conditions -- mostly big blusterly NW near-gales with bright sun, nice! -- and the more I sail her the more impressed I am.

One thing has been puzzling me for some time, and that is a curious shudder or shiver that runs through the whole boat occasionally at anchor.  It doesn't seem to correspond to maximum wind gusts -- I thought it was maybe the rig shaking, the forestay oscillating, something like that, but the timing is odd, almost random.  Sitting in the cockpit I observed that the shudder or shiver did correspond with an oscillation in the tiller, perhaps in response to small waves or turbulence as the boat dances around in the gusts against the tide.

So I just wondered, does anyone else's Contessa occasionally tremble all over (like a minor earthquake) while at anchor?  Should I be worried?  I don't recollect either of my previous boats doing this, but they were quite unlike a Contessa, so that may mean nothing :-)

And now back to singing her praises:  What a nice little boat she is!  She's been reliably making 5.5-6.5 in the good strong air on any point but a dead run.  (Yes, I saw 8.1 on the gps screen once or twice but that was with a favourable tide!)  A beam reach is of course a hoot and a half in 20 kts and relatively low sea state :-) -- I hurt my face grinning :-)  I find that she's happy in 18-22kts with just one reef in the main and the whole genoa (mine is a roller-furling job, I'd  call it a #2, maybe a 110 or so), but in gusts to 25+ I need to roll up at least a half of the genoa.  Steering is mostly easy, though she does do a bit of "wallowing in the following" (who doesn't?).  Her motion is pleasant in all conditions so far, never pounds or slams, never does anything startling.  Anyway, I'm very pleased now that I've had her out in some fairly serious air.  Light air performance can always be enhanced by putting up more acreage of sailcloth :-)  but a boat that won't handle in heavy air is kind of a dead end.  This one handles very nicely when things get sporty, and that's just great.

..... Bound is boatless (wo)man .....

Posted By: George Isted
Date Posted: 31 Jul 2013 at 2:32pm
Sounds to me like the mast is oscillating at a particular wind speed, you could try and temporarily wrap a halyard (or thicker rope) around the mast in a spiral as this will disrupt the airflow over the mast, no good for sailing but will rule it out.  Could be related to your question about the rig setup.
A shudder the rig past will be compounded if the mast is able to move where it goes through the deck, worth checking that the mast is held firmly in the deck hole using thick rubber and/or small wooden wedges.
Good to hear you are enjoying your boat in all conditions.  


George Isted
Contessa 32 "Concerto"
Co32 Class Measurer and ex Class Captain.

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