How to adjust tension on stays

Moderator: GreenLake

How to adjust tension on stays

Postby hectoretc » Fri Oct 21, 2011 10:57 pm

Greetings all,
If one cuts or replaces a mast, or replaces one or all of the stays, how do you know how tight to re-set them, and how do you balance them?
I assume you could put boards under the trailer tires to level the boat laterally, otherwise it's going to be tough to check a plumb vertical. But even with that (what part of the boat to use for level reference?), once the mast is vertical laterally, how tight should the sidestays be, and how do you measure it?
Is the mast supposed to be vertical fore & aft as well? What would be used for the fore/aft vertical reference? The seats? I have read that people cant the mast fore or aft for racing, but what is considered default or nominal setting for normal use, and again, how much tension should the forestay be set to?

Thanks
DS #6127 - Breakin' Wind - From the land of 10,000 lakes, which spend 80% of the year frozen it seems...
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Postby GreenLake » Sat Oct 22, 2011 12:22 am

While your mast should be vertical in a sideways plane, you don't want it vertical fore and aft. You do want some mast rake to get the correct balance.

North Sails site has some tensioning advice
http://www.northsailsod.com/class/daysa ... uning.html
The dimensions may need to be adjusted based on changes in mast length, though, (but the relative dimensions would be very similar, as the angle is very acute.)

But this has been covered here before, I'm sure.
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Postby shawn » Sat Oct 22, 2011 8:19 am

The headstay length is fixed per the North guide so the tension is done with the sidestays. Mine had knurled nuts which you did by hand, never giving the tension that racers require. So I used to take the mainsheet attach it to the end of the boom and then sheet in really tight on the centerline until I was satisfied with the mast shape and then easily tighten the stays by hand. When I eased the mainsheet the mast was all set, some trial and error will tell you how much you should tighten and then you can mark the turnbuckles to return to the same setting.

Shawn
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Postby hectoretc » Sat Oct 22, 2011 8:33 pm

Thanks GL & Shawn,

There is such an amazing wealth of information in this forum, and there is so very much I need to learn, that in an attempt to not re-ask every single question everyone else who's ever purchased a sailboat askes, I've started reading (from oldest to newest) all of the posts in each section.

Had I read only a dozen more posts in the DSII section, I would found this answer from 2007, which very closes jives with GL & Shawn's responses. It does also give a practical "hands on" solution for lateral adjustments which I will try next time the boat is in an area high enough that the mast can go up again (spring I think). Saves the "trying to level the boat" challenge.

Roger wrote:You don't likely want to invest in a Loos guage at $90 to tension such a small rig, and you don't have to. Once the mast is up, ensure that it is STRAIGHT up. Do this by using a tape measure from the main halyard (taped to the shackle and run up to the top of the mast, then measured to each aft corner of the boat. The measurements should be the same. Adust each shroud by hand to get it equal on both sides, then tighten them by hand. The fore and aft set of the mast should also be 90 degrees from the cuddy sole. If you want mast rake don't have anything further aft than 2 degrees to start with. Tension the forestay to take out any slack using a tool for the last few turns. This will give initial tension to the rig. Now go sailing and notice if there is any slack in the leeward shroud. If there is, tighten them up a few turns (each side equally) with a tool. When you are sailing on a beam reach, the leeward shroud should be 'just' slack, not sloppy. Continue to adjust each shroud equally until you get this tension. Now to focus on the mast rake. Your boat should ideally round up into the wind and stall within a few boat turns when you let go the tiller. This is called weather helm. If you are fighting the tiller all the time, then you have too much weather helm. If your boat turns downwind, you have too much lee helm. To increase weather helm, reduce tension in the forestay and increase the tension in both shrouds so that each shroud still has equal tension. This will move your mast back and thereby the center of effort, which will increase weather helm. If your boat is perfectly balanced (bad) or turns downwind, (even badder), then slack off (equally the tension in the shrouds and increase the tension in the forestay. Only do a few turns at a time. It may take you several sails to get the boat where you can control the tiller with finger tip control, yet still have it round up into the wind if you let go the tiller. Once you have that, lock your turnbuckles with wire, mark them, or tighten down the restraining nuts so that they do not change over time. If using shroud adjusters, mark the holes. Shroud adjusters will not allow as fine tuning as turnbuckles.

Shrouds will stretch over time, and new ones will stretch in the first few seasons, so will need readjustment in the first few years.

If you do have a Loos guage, follow the directions for setting tension, but you still have to go through the above procedure to get the mast straight from side to side, and the rake perfect to get some weather helm. All that a Loos guage does is identify the amount of tension based on the size of the shroud.


I've also printed out the linked North Sails instructions and will stuff them in my sail bag as a reference for next year.
DS #6127 - Breakin' Wind - From the land of 10,000 lakes, which spend 80% of the year frozen it seems...
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Postby GreenLake » Sat Oct 22, 2011 9:47 pm

If you have someone really experienced you can invite along, that would help you fix the proper degree of weather helm and forestay sag. Even if you follow the instructions, an additional set of experienced eyes would probably help.
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Postby hectoretc » Thu Oct 27, 2011 11:37 am

In some other posts I've seen references to fairly strong load settings for the stays.

http://forum.daysailer.org/forum/viewtopic.php?t=3258

In this post numbers such as 250-300 lbs of pressure are suggested.
How would anyone raising a mast (even with the sidestays pre-attached) ever get the headstay attached to the stemhead having to put a couple hundred pounds of pull on the line just to get the pin through the stemhead? Or am I misunderstanding what these numbers represent?
DS #6127 - Breakin' Wind - From the land of 10,000 lakes, which spend 80% of the year frozen it seems...
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Postby GreenLake » Thu Oct 27, 2011 2:27 pm

You tension the stays after you raise the mast and attach the headstay?
Last edited by GreenLake on Fri Oct 28, 2011 12:40 am, edited 1 time in total.
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Postby K.C. Walker » Thu Oct 27, 2011 7:50 pm

I don't know how many pounds of tension I've got on the head stay but it's quite a bit. I leave my adjusters set the same all season (so the leeward shroud just starts to go slack at 8 kn, close hauled). I also leave my side stays attached. I also have the standard tabernacle.

Before raising the mast I attach the jib halyard to an old 5:1 vang and attach that to the stem head. As I am walking the mast up, I pull in the jib halyard. It's pretty easy to raise the mast by myself without leaving the cockpit. I cleat off the jib halyard, go forward, pull on the 5:1 tackle, and pin the head stay. It seems like putting in the ring ding is the worst part.

I used to use the trailer winch to pull the tension on but this is easier.
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