Using a Cunningham

wotayottie

wotayottie

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An interesting post on my other thread about backstay tension got me wondering:

dunedin said:
In our case cunningham tension has much more influence over sail set - plus careful positioning and use of reef lines.
This is with a cruiser / racer design sailed as fast cruiser and not lacking in pace upwind as a result.
Click to expand...

I've never used a cunningham but could always rig one. But I have never seen the point since unless the sail slides are jamming in the groove, the tension along the luff of the main will be constant top to bottom ( the sail would move up and down the mast track if this werent so) so adjustments can be done just as easily with the halyard as a cunningham.

Am I right? If not, why not?
 
Yes the cunningham and halyard tension do exactly the same job.

But this is one of the most important sail controls, and should be adjusted regularly to suit wind strength and course.
Typically need to depower mainsail and blow kicker to tension halyard sufficiently (not a huge hassle, and just 60 seconds or so if all controls led back).
Pulling down on the cunningham (with a 16:1 or more tackle) can typically be done without easing other controls - though may mean a trip to the mast

Racers need cunningham as mainsail will be sized to be exactly on the black measurement bands in light conditions, with minimum / downwind luff tension. So in any breeze upwind pull on cunningham to tighten luff, without sail going beyond the bands
 
It's harder to adjust the halyard tension on the fly as the wind strength changes. If you're close hauled you're going to have to get crew off the rail, dump the main or luff up, then get them to grind away.

With a Cunningham, the mast man can quickly lean in from the rail and adjust it and get back to hiking pretty much straight away.

Even if you've got constant wind strength, mistakes are made. If you round the leeward mark and the pit forgets to put back on the halyard tension that was eased at the windward mark, a Cunningham is a quicker bodge than all the hassle to change the halyard tension close hauled.

Beware that the Cunningham doesn't have exactly the same effect as the halyard. It only affects the luff, so will increase twist in the leech. So when you use it you'll have to check the effects on sail shape are acceptable. When I say you I mean of course your main trimmer as you'll be too focused on driving to have a debate on leech twist.
 
wotayottie said:
An interesting post on my other thread about backstay tension got me wondering:



I've never used a cunningham but could always rig one. But I have never seen the point since unless the sail slides are jamming in the groove, the tension along the luff of the main will be constant top to bottom ( the sail would move up and down the mast track if this werent so) so adjustments can be done just as easily with the halyard as a cunningham.

Am I right? If not, why not?
Click to expand...

the main (& genoa) are hoisted to the "Black band" ( max hoist allowed) the sail camber is then adjusted via hauling downwards via the Cunningham hole.


http://www.ybw.com/forums/showthread.php?t=156112
 
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Not only is there the black band issue (ie the sail is cut with the maximum allowed luff length in about 15 knots of wind), but the halyard has actually the same function as a sliding gooseneck, not the cunningham. But these are rare these days.

So with a fixed gooseneck, imagine the cunningham being progressively pulled down until it eventually reaches the same point as the tack. Then the area of the main that is a triangle between the tack, the cunningham and the clew will be folded in on itself and thereby 'out of action'. This flattens the lower part of the sail more than halyard tension alone, even if you were allowed to hoist beyond the black bands.
 
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TimBennet said:
Not only is there the black band issue (ie the sail is cut with the maximum allowed luff length in about 15 knots of wind), but the halyard has actually the same function as a sliding gooseneck, not the cunningham. But these are rare these days.

So with a fixed gooseneck, imagine the cunningham being progressively pulled down until it eventually reaches the same point as the tack. Then the area of the main that is a triangle between the tack, the cunningham and the clew will be folded in on itself and thereby 'out of action'. This flattens the lower part of the sail more than halyard tension alone, even if you were allowed to hoist beyond the black bands.
Click to expand...

there was also a black band at the gooseneck so the sliding tack could go no lower than the band
 
To put it without racing jargon if possible, the cunningham tackle is used to tighten the main halliard luff tension.

It's usually a small 6:1 or similar purchase on dinghies going from the bottom sole either through a cringle eyelet or an attached ( pulley ) block on the sail say about 8" above the gooseneck pivot then down again and led to the hand of either the crew or helmsman depending how the boat is set up; on a lot of racing dinghies this will be duplicated with the lines running to both sides.

The general idea is to tension the cunningham lines when going upwind requiring a flatter sail - also pulling the clew outhaul tight for the same reason - then letting both lines a little slack when running.

This is all racing stuff, ignore if just bimbling along on a nice afternoon ! :)
 
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When I sail I pretty much hoist the main on the halyard at the start of the day and then use the cunningham or gooseneck to adjust the sail as needed.

Technically they may be equivalent, but it is much easier to tighten the luff of the main by pulling down on the gooseneck or cunningham than pulling up on the halyard - I suspect because pulling on the halyard involves pulling against the mainsheet and kicker, whereas the cunningham can be tweaked without touching them, and so without altering the sail shape.

However the cunningham does also alter the shape of the sail - in effect it removes some of the luff length and so moves the draft forwards
 
bedouin said:
When I sail I pretty much hoist the main on the halyard at the start of the day and then use the cunningham or gooseneck to adjust the sail as needed.

Technically they may be equivalent, but it is much easier to tighten the luff of the main by pulling down on the gooseneck or cunningham than pulling up on the halyard - I suspect because pulling on the halyard involves pulling against the mainsheet and kicker, whereas the cunningham can be tweaked without touching them, and so without altering the sail shape.

However the cunningham does also alter the shape of the sail - in effect it removes some of the luff length and so moves the draft forwards
Click to expand...

these should be eased / released prior to tweeking the halliard.
bigger boats have fixed goosenecks
 
I had a main made which had a full foot. Taking in the cunningham reduced the bag in the foot and reduced heel quite a bit in blowy conditions.
Worked for me.
 
Wata...

Have you caught racing sickness?

It is very infectious and easily transmitted of you come into contact with people who have it. It can cause severe aggression and mood swings. It is also very harmful to the wallet and liver!! Once infected it can take many years to effect a cure.
 
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