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Rear Stay adjuster

2K views 15 replies 10 participants last post by  FinallySailing 
#1 · (Edited)
What is the Purpose of the Rear Stay Adjuster

I mean what is the advantage...? I have seen single line hydraulic pull downs, glorified turnbuckles with big wheels, and all sorts of contraptions to "squeeze" a split rear stay...

What for and when do you yank it...??

I should mention I have a masthead rig and split back stay with no known adjuster...

so question is do I "need" one...?

(picture not mine)
 

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#2 ·
If you have a split backstay you could easily add the rig shown in your pic, what you'll gain is better forestay tension, less sag and better pointing.

Whether you care or not depends of if you race, or if you have to sail to windward routinely - then the few degrees can translate into big gains, better VMG and that last park buoy....
 
#3 ·
Hey,

The backstay adjuster is used to control forestay tension and main draft position.

When sailing down wind you want to ease the backstay to allow the mast to move forward. This allows a spinnaker to project more sail area.

When headed upwind you don't want the headstay to sag. By tightening the backstay the headstay will get tighter and you will point better. As the wind starts to increase, tensioning the backstay more will move the draft of the mainsail forward so you get less heel and more forward drive.

The boat I race on has an adjustable backstay. The first unit was a threaded rod and a ratchet handle. That unit worked, but was slow and cumbersome to use. The owner upgraded to a hydraulic unit that it much easier to use. Note that the total adjustment is just a few inches from full slack (doing downwind in light air) to full on (going upwind in 20+ kts of wind).

Good luck,
Barry
 
#4 ·
Is it a constant tension (I could set in the rigging) or just when you need it (add a little trim wise?)

(Barry answered part of that while I was typeing)
 
#5 ·
this will bend the mast and move the top of it aft. That causing the forestay to be tighter and move the center of effort of both the main and jib forward while taking out draft. Want it loose in light air and tight in a breeze in general. Great piece of kit to have. easiest to use with fractional rigs, good with masthead, harder with old style cutters.
 
#7 ·
Backstay on a frac is more about mast bend/flattening main.. in fact without jumpers there's not a lot of change to forestay tension.. that's the job of 'runners' and checkstays (which also control overall mast bend, esp on masthead rigs)
 
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#8 ·
Faster.... I always thought on us Mastheads it was also about headstay sag. You sag it out for more power just off wind, bring it up with more wind and when you are beating to windward. It also helps with rake, and also bend to an extent (not much).

I know with my lowers properly set, I can sag out the headstay with little backstay on, and my aft lowers are tight... but as I bring in the backstay, the forward lowers tighten, aft ease off some, and the forestay really starts to twang. halyard that reaches 8-10 inches aft while hanging a bob at start, to 12-14 inches after full on.

As the wind picks up you can really feel a difference in point as you tension up on the backstay... also in light air, or downwind you can feel the power come back as you back off the backstay... its small and you have to look for it, but it does show itself.
 
#9 ·
Faster.... I always thought on us Mastheads it was also about headstay sag. You sag it out for more power just off wind, bring it up with more wind and when you are beating to windward. It also helps with rake, and also bend to an extent (not much).
Post #2 above...

If you have a split backstay you could easily add the rig shown in your pic, what you'll gain is better forestay tension, less sag and better pointing...
Don't think we're disagreeing here...:confused::)
 
#10 ·
On mashead boats the type of mast section you have will determine what effects backstay tension has. If you have a cruising boat with a big stiff "tree trunk" mast section, the main benefit will be forestay tension, which is a good adjustment to have. If your mast is more performance oriented like the tapered Sparcraft mast on my boat, you get the added bonus of being able to bend the mast, which will flatten your mainsail. It should be noted that mast bend does NOT change your draft position (much). Draft position is controlled by halyard/cunningham tension. Mast bend changes the depth of the draft.
 
#11 ·
Using backstay to get a lot of mast bend on a masthead rig will actually slacken your shrouds as you're 'shortening' the overall height of the mast (think compressing a toothpick between your thumb and forefinger). Checkstays are used mid-mast to limit that effect, and force some increased tension on the headstay rather than further compressing the mast...

All of this is a bigger deal with powerful hydraulics and bendy sticks, of course.
 
#12 ·
Agree with ST. Need to go through the total tune after cranking in a lot of backstay. Often re tension the main halyard. Still think I usually can get a flatter mail with draft forward with some tension in the backstay ( maybe I'm delusional - oh well). Was assuming jackstays on fractional rigs. Also note it works different on boats with baby stays or pre- bent sticks. May get the bend in different places on different boats. On a lot of cutters can use the running backstays to tension the staysail stay when it blows much the way you use the backstay on a sloop or solent. Backstay may not help the staysail stay tension that much so often not adjustable.
 
#16 ·
There is another advantage of having a backstay tensioner for those who trailer sail: Putting some slack into the backstay whilst stepping your mast can make raising quite a bit easier (ideally use a forestay lever as well).
 
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