Beginner questions: Downwind Gusts

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Downwind Gusts

Printed From: Yachts and Yachting Online
Category: General
Forum Name: Beginner questions
Forum Discription: Advice for those who are new to sailing
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=9190
Printed Date: 10 May 25 at 5:36pm
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com

Topic: Downwind Gusts

Posted By: kurio99
Subject: Downwind Gusts
Date Posted: 09 Apr 12 at 2:10pm

Showing my ignorance again. Yesterday, I was out and about on a downwind run. Normally, the downwind runs tend to be the most boring point of sail, but not this time. Got hit by a front where the wind went from about 5 knts to 17 knts in less than a minute. My old dinghy was planing for all that its worth (which ain't much), but couldn't keep up with some of the really hard gusts (30 knts?). The rig was taking a pounding and boat was trying to turn broadside to the wind.

Ideally, I should be hanging on and enjoying the ride, but what is plan B? Do I go with a snap turn to broadside or upwind to take the pressure off the sail?

Replies:

Posted By: bferry
Date Posted: 09 Apr 12 at 2:23pm

You would need to ease the pressure off the sails. Head up slowly onto a broad reach and spill the wind by keeping the mainsail eased. you can then head down again when the gust eases or sheet in to continue on broad reach.

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Bernard
Vareo 249
Miracle 2818
Malta

Posted By: alstorer
Date Posted: 09 Apr 12 at 2:41pm

If you round up suddenly you'll almost certainly end it with a swim...

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-_
Al

Posted By: kurio99
Date Posted: 09 Apr 12 at 2:46pm

I should also mention that the sail is not quite 90* due to the shrouds (closer to 70%). As soon as I start to turn, my sail area actually increases in the face of a big gust. A gradual turn might increase my risk of a leeward capsize.

Posted By: kurio99
Date Posted: 09 Apr 12 at 2:51pm

Forgot to mention that I was single handing a two sail boat, so the jib comes out of the shadow of the main as soon as I start to turn. Basically, my sail area gets much bigger.

Posted By: bferry
Date Posted: 09 Apr 12 at 3:06pm

In that case I'd just let the jib fly to reduce sail area.

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Bernard
Vareo 249
Miracle 2818
Malta

Posted By: Neptune
Date Posted: 09 Apr 12 at 4:30pm

Hold on and send it........wooohoo baby! Hope the gust is gone before the shore arrives

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Musto Skiff and Solo sailor

Posted By: RS400atC
Date Posted: 09 Apr 12 at 4:55pm

IMHO, downwind you generally just have to bear off in the really big gusts.
Between gusts you should head up a bit to keep the boat going as fast as possible, reducing the apparent wind. If you need to change direction, then pick a wave and a lull to turn fast to a close reach, then work from there.

Posted By: bferry
Date Posted: 09 Apr 12 at 5:24pm

I agree with you on bearing away, especially if flying a kite, however what I think kurio99 is having trouble with is depowering when having headed as low as possible. Bearing away further would risk an accidental gybe. With the shrouds limiting the travel of the mainsail it is impossible to sheet out the mainsail more than the shrouds allow. Neptute seems to have the right idea!

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Bernard
Vareo 249
Miracle 2818
Malta

Posted By: winging it
Date Posted: 09 Apr 12 at 8:30pm

RS400 is right - you have to bear away, but the trick in big winds is not to be running dead downwind in the first place. Instead, aim to sail on a braod reach. That way you can bear off onto a training run (boom just in from the shrouds) in the gust, ride it out, then head back up again in between gusts. Don't have the board up as far as you normally would, to damp any rolling, and if the boat does start to roll, pull some kicker on. Sit towards the back of the boat and sit out when you want to bear away. If you sit forward and in, the boat will try to head up, contradicting what the rig wants to do.

If you're worried about the gybe then don't - head up and tack, then bear off, sitting out and back as you do so.

Another point: most people find running dull in light to medium stuff, much as you say you do so. If you can learn to work the sail and the shifts and really concentrate downwind you will gain masses. Most people go to sleep on the run - take advantage of this and get past them!

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the same, but different...

Posted By: ColPrice2002
Date Posted: 01 May 12 at 2:17pm

Hi,

this is going to sound totally counter intuitive, but give it a try:-

Assume you're on a nearly dead run (jib won't goose-wing without jib stick).

When a gust hits you, the centre of effort of the mainsail is offset to the hull and the boat will try to gripe up into the wind.

As the boat does this, it heels to leeward and the rudder blade lifts out of the water. The hull shape of the boat will accelerate the turning into the wind, and the boom will hit the water, locking the mainsail and you'll blow in.

It's often linked with a rolling moment.

In this situation

1) run to the transom - keep the bows out of the water at all costs.

2) try to keep the boom out of the water by sitting out.

3) DON'T try to turn downwind - if you do, the heeling force will diminish rapidy, the rudder will suddenly bite and you'll roll in to windward....Just keep a firm hand on the tiller.

If you sail with the boat heeled to windward, then you move the centre of effort (from the mainsail) over the centre of the boat. This means that there is much less force trying to turn the boat into the wind.

It feels horrible (keep a bit more plate down) but is actually more stable than trying to keep the boat upright! As a gust hits you, balance carefully, and use only small rudder movements - you will steer the boat better by changing the heel angle!

Look at the Lasers, Europes etc - downwind they heel so that the mast is well off vertical.

In this configuration, when a gust hits, you can actually adjust the heel by using the rudder (small amounts!).

If it's at all possible, buy a jib-stick and get it in as soon as possible downwind. It really makes a lot of difference to the stability when a gust hits from astern.

(based on an Enterprise with F6+ gusts - no jibstick = swim, jibstick = screamer)

Colin

Posted By: pondmonkey
Date Posted: 05 May 12 at 10:50am

Originally posted by winging it

Most people go to sleep on the run - take advantage of this and get past them!

running downwind is the best time to bail out the boat, eat a banana, enjoy a cigarette, have a moan with the crew about the club catering, text your wife to say you're running late (again) etc... who'd want wind shifts and tactics to get in the way of that?

Posted By: Notl
Date Posted: 07 Aug 12 at 10:15am

An advanced way to deal with this is to sheet in a bit and hike more to the side.
This reduces the sail area but increases the side forces.
The increased pressure on the sail should stop it from gybing.
Sheeting in also holds the boom down.
Bearing away on the gust is essential.
Practice in strong winds is a good idea.
Make sure there are rescue boats at hand.
Also sailing with only the mainsail up is good.
You have to rebalance the boat by adjusting the centerboard so that it is 2 thirds down upwind.
This moves the pivot point aft to compensate.
Does not work if you have a daggerboard.
This setup makes your boat sail like a single sail single hander.
Hope this gives you some ideas.