Main flattener vs outhaul?

[gregcope]

Whats the difference?

On my boom there is a wire to forward end of the boom with a 1:2 clutch on the boom.

There is another line that goes back to a cockpit clutch, marked with “flatener”.

On the main clew there is an eye and another eye 300mm up the leach.

i assume one is an outhaul and another a flatener.

which is which and why?

 

[James_Calvert]

Not quite sure of your question.

Obviously the outhaul has no effect when the flattener is in use. On my old main with a flattener, the clew was fixed.

It seems like your main is cut for a flattener. Most aren't these days, and an adjustable clew outhaul does an equivalent job.

If you've got lines for both, you can play with both of them. Until the first reef of course...

(edited spelling)

 

[William_H]

The simple answer as to which one is which is to give one a pull and see what happens. Does it move the clew or does it move the wire to the flattening reef eyelet 300mm above the clew. I am sure that is obvious to OP.
The flatener is a way to take camber out of the main sail and reduce area slightly while maintaining mostly full sail area when the wind comes up.
For a cruiser or even gently racing If you need a flatener in you might as well pull in the first reef. The reef in itself should flatten the sail nicely.
Much depends on the shape and cut of the main sail. One with much camber down low might benefit with a flattener reef but a mains ail that is fairly flat anyway will not benefit so much except for the reduction of sail area. You will note that you probably have a cunningham ey at the front of the foot which can be used to apply more tension on the luff also to flatten the sail and the 2 together make a mini reef.
So for light winds just set the outhaul tension to loose and flattener right off. As wind comes up tighten the outhaul. More wind pull down the flattener. (release the main sheet as you pull the flattener down) More wind you reef.
If it is more convenient (you are lazy) you can skip tightening the outhaul and use flattener. Or forget flattener tighten outhaul then put in reef. Much depends on what is most convenient for you while sailing. A smaller flat main sail is essential to happy sailing in stronger winds. (over 15 knots) ol'will

 

[RJJ]

The outhaul is at the clew, the flattener is 30cm up.

The flattener tightens the leech so that you can then tighten the kicker / mainsheet without the boom hitting you on the head, even if you have bent the mast using the backstay. On dinghies like FDs, it was hard to get under the boom once the mast was fully-raked.

More subtly, it enabled the mainsail to be measured to the black band for racing purposes while set loose on the foot for power in lighter winds. Then in stronger winds you could flatten the foot without breaching the black band. The measurement is of course no concern when cruising.

As noted, typically use it in conjunction with the Cunningham. A very flat well-twisted sail has much the same effect as a reef. Or just cut the crap and reef.

 

[fredrussell]

My ancient mainsail has Cunningham and flattener on Clew. Very useful for de-bagging(!) my woeful sail. When I replace sail shortly I won’t bother having cringles for flattener or Cunningham.

 

[gregcope]

Thanks all.

All lines goto the cockpit on a Starlight 35, apart from the outhaul that terminates at a clutch on the front end of the boom.

I do no think I have a Cunningham judging from the clutch names.

This strikes me as odd, as I would usually adjust the outhaul lots...

Thanks for the feedback.

 

[William_H]

Thanks all.

All lines goto the cockpit on a Starlight 35, apart from the outhaul that terminates at a clutch on the front end of the boom.

I do no think I have a Cunningham judging from the clutch names.

This strikes me as odd, as I would usually adjust the outhaul lots...

Thanks for the feedback.

In effect having a flattener reef to pull in is like having a 2 stage outhaul. So out haul set for light winds and instead of pulling out the outhaul you pull down the flattener when wind comes up. Give it a try. But you might find you can swap the flattener lines for the outhaul to give you fully variable outhaul then abnadon flattener. ol'will

 

[gregcope]

In effect having a flattener reef to pull in is like having a 2 stage outhaul. So out haul set for light winds and instead of pulling out the outhaul you pull down the flattener when wind comes up. Give it a try. But you might find you can swap the flattener lines for the outhaul to give you fully variable outhaul then abnadon flattener. ol'will

Thanks, thats effectively how I use it. Not by design, but just logic/history.

 

[PeterWright]

Hi Greg,

I suspect the set up you describe is a relic of the last days of mainsails fixed to the boom over the whole length of the foot with a blot rope or slides. Before loose footed mains became almost standard, there was a period when they were cut with a shelf foot to allow extra draft in the sail for lighter airs, pulling the flattener effectively eliminated this camber. It didn't take long for people to work out that with a loose foot secured only at the tack and clew, the same effect could be achieved by adjusting the outhaul.

I bought a Westerly Storm with exactly the setup you describe 25 years ago, still sporting the shelf footed main. After one year, I replaced the aged main with a loose footed one, re rigged the boom to eliminate the flattener and routed the outhaul to the cockpit clutch previously used for the flattener, retaining the 2:1 purchase inside the boom - it worked a treat and gave us better control of the mainsail shape.

I'm pretty sure the main that came with the boat when I bought her was the original and there was no evidence of her ever having a Cunningham - we used the main halyard to adjust luff tension. She didn't have black lines when we bought her, but we added those and were never in danger of exceeding them however hard we pulled on halyard or outhaul.

Peter.

 

[gregcope]

Thanks @PeterWright

This is on a 1997 Starlight 35. The main is loose footed, with what I think is a noticeable "shelf" on the foot for want of a better description that is horizontal and aligns the wing shape of the sail to the centre of the boom (imagine you were looking cross section of the sail from the bottom up).

I intend to go with what you suggest and replace the wire outhaul (that has an odd 2:1 in the boom - I say odd as it seems to be missing a block sheeve in the boom as it does a 180 in the front of the boom fitting as if it should go back to a block...) with a dyneema arrangement at some point using the flattener clutch.

 

[iamtjc]

I suspect the set up you describe is a relic of the last days of mainsails fixed to the boom over the whole length of the foot with a blot rope or slides. Before loose footed mains became almost standard, there was a period when they were cut with a shelf foot to allow extra draft in the sail for lighter airs, pulling the flattener effectively eliminated this camber. It didn't take long for people to work out that with a loose foot secured only at the tack and clew, the same effect could be achieved by adjusting the outhaul.

Peter, thanks for this explanation. I have a 30yr old boat with a mainsail fixed along its length to the boom and couldn't make sense of things people said about the use of the outhaul since it didn't make a blind bit of difference on my boat. I hadn't realised that most modern sails are now loose footed. So your explanation has cleared things up for me.