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-   -   Got caught in a Squall today (http://www.sailnet.com/forums/general-discussion-sailing-related/74013-got-caught-squall-today.html)

Aac 04-29-2011 10:34 AM

Got caught in a Squall today
 
Hello Sailors

I need a bit of advice and hope that more knowledgeable salts could help; I went out today single handed for a half day sail on a 40’ monohull. The for-cast was for 20 to 25 knots in Moreton bay, Brisbane. All was fine until I noticed a storm approaching. About 15 minutes later I noticed the water ahead was white as the rain bucketed sideways. I was already on second reef on the main and the Furling jib was reefed to around 100%. The oncoming squall was pushing me toward a lee shore about a mile away and so I decided to head into it instead of galloping with the wind at 8 knots towards the lee shore. I was also thinking that the wind wouldn’t be more that 30 knots - pretty dum really. In heading into the wind I thought that I would cope by sheeting in the jib (not too tight) and the mains and simply feather the boat close hauled as I have done many times. This worked fine until the wind started to gust to 40 knots and the half furled jib began to beat in an intermittent and uncontrollable manner. I managed to keep it calm for much of the time but every now and then the rig would vibrate with the shock loads administered by the jib.

It seems to me that the windage of furled part of the jib is large in 40 knots of wind and maybe the forstay is not tight enough (even though I manage to point well). I didn’t want the rig coming down and so I heaved to; this calmed things down with a drift speed of around 3.2 knots and 10 minutes later the wind dropped to a respectable 20 to 25 knots again.

The shudders in the rig scared the hell out of me and I was wandering what others have to say with respect furled head sails and sailing into stiff 35 to 40 knot winds. Should I have furled the jib completely and simply relied on the mains which was behaving well; the argument against the main only I guess would be that I wouldn’t be able to heave to nor even make head way.

Would love to hear if others have had similar rig vibrations from a furler head sail or indeed what they might have done differently.

CharlieCobra 04-29-2011 11:09 AM

I've seen that before as well. The amount of turbulence at 40 knots coming around the furled jib is enough to break the air off the surface of the sail. One way to cope is to set the furling line tight, cleat it off, trim the remaining jib tight and then tighten the windward sheet as well. You want what bit of sail ya have out trim pretty hard in heavy winds. At least, that's been my experience. YMMV.

imagine2frolic 04-29-2011 11:51 AM

You should've taken advatange of that 15 minutes. This is why I love my cutter rig. Roll up the head sail, and unfurl the stysail.......i2f

rockDAWG 04-29-2011 12:17 PM

Quote:

Originally Posted by Aac (Post 725160)
but every now and then the rig would vibrate with the shock loads administered by the jib.

The shudders in the rig scared the hell out of me and I was wandering what others have to say with respect furled head sails and sailing into stiff 35 to 40 knot winds.

Excellent post, I would like hear from others too.
I wonder if you can fall off a bit on your heading will eliminate the shudders which I believe it was caused by harmonic vibration.

Without knowing more, I am most likely to heave to in your situation but then one mile to lee shore is nerve wracking. :)

tommays 04-29-2011 01:06 PM

I been anchored out overnight on the J24 when there was enough wind +40 from a passing storm to shutter the heck out of a bare mast

Aac 04-29-2011 01:09 PM

Quote:

Originally Posted by CharlieCobra
The amount of turbulence at 40 knots coming around the furled jib is enough to break the air off the surface of the sail.

I like that explanation. I’ve read a number of threads on reefed furled headsails and didn’t expect to experience a con I was unaware of. A deep reef on a furled headsail looks horrible and I guess they behave the way the look. A stay sail like imagine2frolic suggests is something I need to look into. The mast on my boat is way forward, unlike a cutter rig, with J=4.32m and E=5.9m; I think that I should still be able to fit a stay with a J of maybe 3m –must talk to a rigger.

Quote:

Originally Posted by rockDAWG
I wonder if you can fall off a bit on your heading will eliminate the shudders

This may have helped but the feeling I had at the time was that I had too much sail up to fall off; my guesstimate was even with a second reef on the main and sheeted out there would have been way too much heel. Were it not for heaving to I would have then attempted to drop the main completely.

Probably also worth mentioning that I have spent a total of 193 days on the bay sailing and often 20 knots plus; today was different due in part to the behaviour of the rig.

What I'm trying to get at is how would a 100% jib that is not furled behave; my thought is that it would have been fine. I’ve read a lot on overlapping versus non-overlapping headsails and I am still lost as to what way to go. The current boat moves well to windward with a 135% overlapping head sail in anything under 15 knots of wind; above that though I find that the 135% is too much and the furler is used for reefing – a PITA.

GeorgeB 04-29-2011 02:01 PM

I have a masthead rigged boat and encounter the same problem with my 130 Genoa. Even rolling it up to a “postage stamp” will not eliminate the harmonics – way too much fabric rolled around the headstay. You just have to pull out a little postage stamp and crank on max backstay tension then grin and bear it. My local San Francisco conditions might be similar to yours. In our summer winds (20-30kts), we swap down to a 110 jib. I had my sail maker cut in a full roach supported by vertical battens which gives me pretty good performance. Downwind, we usually rely on the kite for extra power.

cruisingdream 04-29-2011 03:16 PM

roll up the genny & put on the storm sail

smackdaddy 04-29-2011 07:23 PM

I've only sailed in 40 knots once. Lots of times in 20-30. But in that 40, I felt the exact same shuddering you're talking about.

However, I was under double reefed main only (doused the hank-on 110) and stayed off the wind quite a bit (beam-to-close reach). This let me control the shuddering by easing off the main in the gusts.

Definitely spooky though.

Bradhamlet 04-29-2011 08:09 PM

squall
 
The only luck I had was to far reach. I guss what I really did was roll up the head sail and reef the main tight, head into the gusts at 35 to 45 degeres off the wind and the boat responded well. Not always the direction you may want to go, but this has worked for me in these conditions. And yes my friend it was scary as hell for the first 10 min. It thought it almost got quiet when it lowered down to 30/35 kts, nuts ha?


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