# backstay adjustment



## TSOJOURNER (Dec 16, 1999)

would it be correct to say that tightening the backstay on a masthead rig would only tension the forestay?
your thoughts please


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## Giulietta (Nov 14, 2006)

no, not only, it also "stretches the mast's "belly" forward...but its less effective on sailshape than a fractional rig.


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## TSOJOURNER (Dec 16, 1999)

so you cannot flatten the upper portion of the main?


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## Giulietta (Nov 14, 2006)

the roach??? no.............for that you use battens


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## Cruisingdad (Jul 21, 2006)

Huh? I thought you were supposed to use Raid for roaches. How do you use battens? That was why I bought a catalina... don't have no stinkin roaches on our boats!!


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## Giulietta (Nov 14, 2006)

Cruisingdad said:


> Huh? I thought you were supposed to use Raid for roaches. How do you use battens? That was why I bought a catalina... don't have no stinkin roaches on our boats!!


The roach:

The shape of a sail is seldom a perfect triangle. It is common for sailmakers to add an arc of extra material on the leech, outside a line drawn from the head to the clew. This additional part of the sail is known as the roach; mainsails usually have roaches, but they are very occasionally found on specialized jibs as well. They provide additional power for a given mast/boom size.

Since it cannot be supported by tension in the sail material (applied from the corners), it would flap uselessly unless some other provision were made for it. It is therefore supported by battens, held in batten pockets, which extend into the main portion of the sail.

CD.....Just in case


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## sailingdog (Mar 19, 2006)

Giu-

I thought we were all going to get him a copy of this for Father's day...


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## Cruisingdad (Jul 21, 2006)

Ok, would you help me with another definition. I am not sure about this one.

Boom.

1. a loud, explosive sound.

2. A part of the rigging of a sail boat which holds the bottom of the main sail.

3. The result of not using a preventer.

4. A sound followed by weeks of cursing, dry feet, and thousands of dollars.

5. An error made by a portugese sailor that CD will never let him forget about!


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## Cruisingdad (Jul 21, 2006)

Sorry to hijack your thread mr31 (smile). Just harrasing the Portugese. He deserves it!!

- CD


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## TSOJOURNER (Dec 16, 1999)

no problem
when i say flatten i mean taking draft out of sail. heavy air or very light airs.


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## sailingdog (Mar 19, 2006)

Bending the mast, via tightening the backstay, will flatten the head sail and the main sail. It is a trick often used to depower the sails a bit in heavy winds...


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## Gary M (May 9, 2006)

It depends on whether your mask will bend or not. On many older crusing designs the mast was very stiff. If you mast will bend then when you tension the back stay it pulls the center of the luff forward which flattens the main.

In either case it will tension the head stay and thereby flatten the head sail. 

More outhaul, cunnigham, halyard tension or flattening reef can also flatten the main. 

Gary


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## tdw (Oct 2, 2006)

There's also halyard tension to be considered. Increasing / Decreasing halyard tension moves the draught of your main fore and aft. The heavier the winds the flatter you need the sail so you need more halyard tension. In lighter air you want more belly in the sail.


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## 2ndimpression (Jul 5, 2006)

Ok how about the forestay. If you run a looser forestay would you guys agree that it alters the angle of attack and allows you to point higher but also gives the sail more power. When you crank on your backstay you tighten that forestay, take power out of the jib and also the main cause the middle of the mast bends forward. Thats the idea im going on with my tuning any ways and I can really notice it, i'd almost say it kills nearly 10 degree's of heel when i crank the backstay on hard.

Any comments?


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## tdw (Oct 2, 2006)

2ndimpression said:


> Ok how about the forestay. If you run a looser forestay would you guys agree that it alters the angle of attack and allows you to point higher but also gives the sail more power. When you crank on your backstay you tighten that forestay, take power out of the jib and also the main cause the middle of the mast bends forward. Thats the idea im going on with my tuning any ways and I can really notice it, i'd almost say it kills nearly 10 degree's of heel when i crank the backstay on hard.
> 
> Any comments?


You are pretty much correct, it's all basically as Giu has explained it. Add in some halyard tweaking and awaaaaaaaaaaaaaaaaaaaaayyyyyyy you go. 

The tight stay/halyard tension in bigger winds, looser in light.

Oh, and outhaul tension on your main also comes into play.


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## TSOJOURNER (Dec 16, 1999)

not sure i understand how the mast bends being its a masthead rig. unless the point of bend is caused by the shrouds. i can see the rake increasing and the forestay tightening.


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## Giulietta (Nov 14, 2006)

Get a wooden stick, two strings and try it yourself.

Altough less effective at performing mast "bend" than fractional rigs, masthead rigs still flex some forward, when you pull the backstay because the mast being pulled back flexes as it can't shrink, so it can only go forward.

Fractional rigs allow better control as they can flex more without pulling on the stay much. And allow conditions where you would like a flexible forstay and a tight main sail. That's why race boats have fractional rigs.


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## TSOJOURNER (Dec 16, 1999)

ok. what keeps the mast from bending the other way as it did on my stick / string test.


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## Giulietta (Nov 14, 2006)

What other way???


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## TSOJOURNER (Dec 16, 1999)

bending toward the stern


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## Giulietta (Nov 14, 2006)

It can't, the mas is slightly tilted backwards, its called rake, it has the shrouds (that will not alow stretch forward by belling back), that would not allow it, and mainly:
*
Your pulling back, not forward.*


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## TSOJOURNER (Dec 16, 1999)

ok if i add some rakeit always bends the right way. thanks for the help


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