Flattener??

[surekandoo]

My mainsail (Limbo 6.6) has a set of reef cringles about 8" up from the foot. I'm told these are for flattening the sail. How does one go about this? I have 2 main reefing points further up the luff & leech of the sail to which my 2 reefing lines are attached.

The Limbo is easily overpressed and likes to be reefed early, so I'd like to use the "flatteners". Does this mean I'll have to use one of the existing reef lines or can it be done some other way?

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[tony_brighton]

Think its for a cunningham

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[surekandoo]

yes, but how do you fix it up? I thought the cunningham cringle was on on the luff of the sail, so what's it's partner on the leech do?

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[ccscott49]

The luff one is the cummingham, the leech one is the flattener. How you rig it on your boat, I don't have the foggiest idea.

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[northener]

cunningham can be easily set up with a tackle to the base of the mast.
flattener will be easy if you have a second sheave at the boom outhaul end. I didn't have one on a folkboat and so used a fixed outhaul with the adjustable outhaul through the sheave - up through the flattener cringle and down to an eye I had to fit under the boom - it worked quite well.

Can't remember exactly but I think the cunningham takes out depth in the luff - like the halyard but due to friction a bit lower down and maybe easier to adjust depending on your setup. Flattener as it says flattens main depth further back in the sail.

I found it very worth doing on the folkboat.

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[snowleopard]

the cringle in the luff is, as the others have said, a cunningham. rig a line through it and pull down to stretch the luff and bring the draft further forwards in stronger winds.

the cringle in the leech is for a flattening reef. probably easiest to run the outhaul line to it then you can haul the foot of the sail flat without having to stretch the foot rope. (i prefer loose-footed sails which can be pulled flat with the outhaul).

flattening the sail reduces its power and reduces weather helm in strong conditions upwind.

i recommend that if you want to play with these controls you get a book on sail trimming (there was also a series on it in YM recently).

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[andy_wilson]

Cunnigham at the luff is used to tighten the luff and bring the shape of the sail forward when you can't do it by tightening the halyard (either 'cos your tackle isn't up to it or the headboard it touching the crane).

Flattner is at the leach and can be administered by the outhaul or an additional reefing line. Very useful to raise the boom a litle if rolling down wind.

You can use them both together as a mini-reef.

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[surekandoo]

Re: Cunningham. Does that mean that the main halyard needn't be really tight to start with and extra "tension" to the luff can be added by tightening the cunningham?

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[extravert]

The main halyard and Cunningham flatten different parts of the sail. The halyard affects sail shape from the top downwards, the Cunningham from the bottom up. Because of friction in whatever means your mainsail is attached to the mast (probably groove and bolt rope), you can haul as hard as you like on the halyard and it will have little affect on the sail shape in the lowest third of the sail. This is where the Cunningham is used instead.

Main halyard and Cunningham tension are usually applied somewhat together, but you apply each sufficiently to achieve the sail shape you require in the sail area that each one controls.

When going from a beat to a reach and you want a fuller sail shape, you can let off the Cunningham. Often though the sail is a bit reluctant to slide back up the mast evenly, and you get a baggy wrinkly bit at the foot. At this point you need somone hefty to go up on the deck and give the sail a whallop.

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[surekandoo]

Thanks, everyone, that's great.

Sounds as though I'll have a few more bits of string to pull & fiddle with!

Next project - Spinnaker??!!??

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[MUS]

Inky,

We never quite got round to rigging up the cunningham on Eau de Vie. We've now got a new mainsail so don't want to stretch it too much at the moment, but if your sail is a few years old a cunningham is probably a good thing to have for moving the draft of the sail forwards.

We now have a loose footed main so the outhaul is quite effective at flattening the main. I've rigged up a 4:1 cascade inside the boom which seems to work well.

Adding a dinghy pulley hook (don't know correct name for this) on the end of the outhaul would double the power and make it easy to move the outhaul to the flattening reef cringle when required. Never tried this however, so it might not work!

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[wiggy]

Come on get it right, the flattener is used to raise the end of the boom slightly when close reaching in a breeze to keep the end out of the water and is best set up with dedicated outhaul or spare reef line.
The cunningham has same effect as putting on extra main halyard-flattens of main, good for going up wind in a breeze.

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[Strathglass]

correct

As has been stated on the last past. The flatener is used to reduce the drive of the main.
It has several functions.

A completely independant line is required to contol it.

This line may require some form of mechanical advantage depending on the sail area of the main.

To set it the mainsheet and kicker must be released. The kicker must have enough range to allow the boom to rise.

It can be look on as the first reef (before the first slab).

Historically it dates from the IOR days when a boom dipping into the cockpit was used and the flatener was used to raise the boom horizontally out of the cockpit.

Very easy to use and nothing to do with the cuningham (other than it also being a sail control)

Great to use in heavier weather, especially off the wind, as it raises the end of the boom, usually above head height and if the craft is heeling excessively can often make the difference between the end of the boom being clear of the water and dragging in the water (with the subsequent potential serious consequences) on a hairy close reach.

An easy control to use and rig. It is even useful on the wind and can often save putting in the first conventional reef in marginal conditions.

More applicable to a masthead rig as a fractional rig gives more control of mainsail power.

Iain





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