# Tension of Standing Rigging



## tagster (May 7, 2007)

So preparing for my trip I've been checking up on and fixing item after item on my boat...and I've noticed that my stays are all completely different tensions.

I have a lot of them.

On the foremast:

Two forward stays
Three standing/main stays
Two strongbacks (high tension running back stays)

On the main mast:

One forward stay (rigged to the foremast)
Four standing/main stays (one forward one aft and one pair of two center of the mast)
One fully adjustable running back stay (only tightened/loosened by hand using some compound pulleys and a line clip - whatever those are called)

How tight should each stay be? I'm fairly sure they should be balanced around the boat, but how much give should they have? Should I be able to shake them with my hands?


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## Valiente (Jun 16, 2006)

Sure, if you go downwind in five knots of wind.

Otherwise, the tension of the stays is usually determined by a number of factors, primary among them the type of mast you have, the diameter of the stays and shrouds, the "rake" of the mast, and the type of sailing you do.

Most stays are too slack, i.e. the rig is not optimally tuned. This can be seen on each tack, where the lee shrouds are slack. Too much slack leads to too much mast movement, work hardening, wear and crappy sail performance: The stays are the "ligaments" of the rig, with the mast, hull and chainplates forming the "skeleton" which transfers the power of the wind in the sails to move the boat. Slack stays=poor transfer, wear and eventually failure.

Consider borrowing or buying a Loos or other type of tension gauge, and determine the usual rig tensioning for your boat. Check all chainplates FIRST, because you want to ensure that the reason the stays are loose in the first place is because the chainplates are half pulled apart.

Ask for help. It's not an amateur job, but it's one easily learned and the results may surprise you.

Rigging Tension: Information from Answers.com


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## sailingdog (Mar 19, 2006)

Valiente said:


> Sure, if you go downwind in five knots of wind.
> 
> Otherwise, the tension of the stays is usually determined by a number of factors, primary among them the type of mast you have, the diameter of the stays and shrouds, the "rake" of the mast, and the type of sailing you do.
> 
> Most stays are too slack, i.e. the rig is not optimally tuned. This can be seen on each tack, where the lee shrouds are slack. Too much slack leads to too much mast movement, work hardening, wear and crappy sail performance: The stays are the "ligaments" of the rig, with the mast, hull and chainplates forming the "skeleton" which transfers the power of the wind in the sails to move the boat. Slack stays=poor transfer, wear and eventually failure.


Not to mention the shock loading that can occur with a loose rig... the sudden transfer of the tension and load from one side to the other can cause a catastrophic failure in a gybe, and possibly to the loss of the mast.



> Consider borrowing or buying a Loos or other type of tension gauge, and determine the usual rig tensioning for your boat. Check all chainplates FIRST, because you want to ensure that the reason the stays are loose in the first place is because the chainplates are half pulled apart.


I think you meant to say that "you want to ensure that the reason the stays are loose in the first place is *not* because the chainplates are half-pulled apart." A loose rig due to badly adjusted stays and shrouds is one thing, a loose rig due to failing chainplates is a different beastie altogether.


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## Valiente (Jun 16, 2006)

Yep, that's correct. Inspect the chainplates for wear, oval boltholes and cracked knees first, prior to spinning the turnbuckle to half a ton of tension.


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## tagster (May 7, 2007)

Heh, shows what I know.

I'll buy a tension gauge and see if I can't find a local expert to help me out with this. I don't really know anyone suitable, maybe I'll hire someone.

Determining the "usual" rig tensioning for my boat is going to be very difficult if not impossible. There aren't very many of these boats out there. Although my tensioning might need to be similar to other models by the same shipyard, but I would sort of doubt that since the other models this size have completely different rigging.


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## James Kenyon (Apr 1, 2016)

I have just purchased a rig tensioning tool. I have a Leisure 23SL and am trying to find out what tension to set on my 4mm stainless steel rigging but can't find any reference to tensioning the rigging anywhere. Can anyone help please


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## chuck5499 (Aug 31, 2003)

tagster said:


> Heh, shows what I know.
> 
> I'll buy a tension gauge and see if I can't find a local expert to help me out with this. I don't really know anyone suitable, maybe I'll hire someone.
> 
> Determining the "usual" rig tensioning for my boat is going to be very difficult if not impossible. There aren't very many of these boats out there. Although my tensioning might need to be similar to other models by the same shipyard, but I would sort of doubt that since the other models this size have completely different rigging.


This is exactly what we did just before we headed out 8+ years ago. We had a Loos guage but what should the tension be. Had a professional rigger come over, a guy who a lot of racers hired for their boats, and had him tune the rig and wrote down the settings. Each year I check the rigging. Had to change out one stay in Trinidad before we left for an Atlantic crossing and again had a pro check it - that was after 5 years. 
On our third year in the Med we noticed that tension measures were close to what they were but we had a stay that looked liked it needed addition tension but not sure if it would move the stick a but to much so had a pro take a look at it in Sicily and he agreed that it needed a bit of turning and adjusted both sides to keep it correct.

Have a pro do it, get a Loos guage and write down the settings then keep it up.


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## SanderO (Jul 12, 2007)

NB that as you increase the rig tension you are shortening the length of the shroud... and this means that you are forcing the hull to deform... ever so slightly. You can determine how much increase by how much you shorten/tighten your rigging once it is not slack (hand tight).. by measuring the length reduction from screwing down the turnbuckles.

You tension a shroud to 15% of its yield strength.

It is a fundamental requirement for all rig types that the
cap shrouds are correctly tensioned. The cap shrouds are
adjusted at the dockside, but final tuning is done while
sailing. The table beside applies to standing rigging using
1 x 19 stainless wire. This is the most commonly used
material for standing rigging.

Your aim should be to tension the cap shrouds to 15-20%
of the breaking load (the final check on tuning should be
left until you are under sail). Then you know that the lateral
staying is optimal both for the security of the rig and for
sailing performance.

There are measuring instruments of greater or lesser
reliability for this purpose on the market. Seldén has
developed a simple method of obtaining the information
you need with material you probably already have. What
you need to know is:

*• All 1 x 19 stainless wire stretches under load, but returns
to its original length when the load is removed. 1 mm
stretch per 2 m wire is equivalent to 5% of the breaking
load, irrespective of the diameter of the wire.*

• A grp hull, on the other hand, changes its shape permanently
when the rig is put under load. This makes it
necessary to set up the rigging again after some time.
This applies particularly to new yachts.

• At the dockside, both cap shrouds always have the same
load. If you tension the starboard shroud, the port shroud
is affected to precisely the same extent

The following materials are required:

1. A 2 metre long measuring rod (a folding rule is recommended)
2. Adhesive tape
3. Vernier callipers

• Start with the cap shrouds only hand-tight. The rig is stayed
with the lower shrouds and the forestay and backstay.

• Tape the upper end of the folding rule to the starboard
cap shroud. The lower end of the folding rule must be
approximately 5 mm above the upper end of the wire
terminal. Measure the distance between terminal and
folding rule exactly. This is index 0, let's call it point A.

• Tension the starboard cap shroud until the distance is
A + 1.5 mm between the terminal and the folding rule.
Measure using the vernier callipers.

• Leave the folding rule attached to the starboard shroud,
and move across to the port side and tension the shroud
rigging screw the equivalent amount.

• At intervals, check the starboard side to see how much
the folding rule has moved from the end terminal. When
there is a gap of A + 3 mm, the cap shrouds are tensioned
to 15% of the breaking load of the wire (3 x 5% = 15%).

If the mast is not straight, adjust the lower shrouds, intermediate
shrouds etc.

The folding rule method can be used on other stays, such
as the backstay and forestay (without jib furling system).
It can also be used for Dyform- or rod rigging, but please
take the difference in stretch into account compared to
1 x 19 wire.

The breaking loads for various dimensions of 1 x 19 strand wire.

Wire Ø..................kN ....................lbs
Ø 3.......................8....................1,770
Ø 4......................14...................3,090
Ø 5......................22...................4,860
Ø 6......................31...................6,845
Ø 7......................43...................9,490
Ø 8......................56.................12,360
Ø 10.....................88..................19,425
Ø 12....................126.................27,815
Ø 14....................171.................37,750
Ø 16....................216.................47,680


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## Barquito (Dec 5, 2007)

Nice write-up SanderO. One part I don't understand:



> • Start with the cap shrouds only hand-tight. The rig is stayed
> with the lower shrouds and the forestay and backstay.


Wouldn't it make a huge difference, that the port and stbd shrouds may not start at the same length? Do you just center the mast after getting to the proper tension?


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## Jaramaz (Aug 9, 2013)

Where I am sailing we put the boats on the hard over the winter. Usually without masts, ie unstep in the fall and step in the spring.

Should we have pro's to do the rigging? No reason, none at all. It is easy-peasy to set the rig. 

There are many methods, each to their own, but most work fine. There are many theories as well, the same with those. 

When I step the mast I make a first setting of the rig. As both rig and boat will have stretched after a week, this is just a preliminary setting. Oh yes, start with the cap shrouds. see to that there is no inversion. As I have a partial rig, no real issues with fore and aft stays. 

Next step happens 1-2 weeks later. Tighten so it feels right, no science behind this. See to that the mast is stright. This is usually enough. Possible to follow up with a sailing tour an afternoon in about 8-10 m/s wind (16-20 knots). Lee shrouds should just start to slack. 

It is so nice to claim a very tight rig. Works fine for racing. But no need for normal cruising. Problem with high tension is the high static forces applied on the boat, all the time. 

/J


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## Stumble (Feb 2, 2012)

First and I have repeated this ad nauseum, YOU DO NOT TENSION THE SHROUDS TO SOME % OF THEIR BREAKING STRENGTH. It may be true that most shrouds are tensioned to between 10-20% of their MBL, but this is not how you set tension.

There are two goals with rig tension, the first is to induce proper prebend. Basically how much the face of the mast bends backwards over the length of the mast, from the hounds to the top. Prebend really changes based on the cut of the sail and the conditions, but most cruisers set it for 15kn of breeze. Ideally you reduce prebend for light air, and increase it for heavy air, but many cruisers just don't bother, or have a hydrolic backstay required to change it on the fly.

Anyway, after the amount of prebend is set, then the only tension to apply is just enough to keep the mast in column while sailing upwind. That's it. How much tension it takes just depends on the boat. It doesn't take a professional, and it isn't that complicated.

0) set prebend based on the cut of the sail
1) at the dock get the top of the mast centered by snugging up the top shrouds and working your way down the rig.
2) once the mast is centered make sure all the shrouds are snug, you can put a gague on them if you want, I don't bother. If you do just set them to the same tension. 
3) go sailing and beat upwind in 5-10kn of breeze. Ideally in flat water
4) while beating look up the rig, is it still in column? If so you are done, but it won't be. So take in two full turns on the leeward shroud.
5) tack the boat
6) take up two full turns on the leeward shroud (So the shrouds on each side match)
7) look up the mast, is it in column? If not then take in two more turns on the leeward shroud
8) go back to 5

Once the mast remains in column on each side, take a tension reading on the shrouds. Then equalize them. Take a 1/4 turn off of the higher and add 1/4 turn to the lower. Then remeasure and confirm the mast stays in column. If it does then you are done, if not then you may have a slight imperfection either in the mast but placement, the mast hounds, or the chainplates. Track those down if you want, or just retension until the mast stays in column on either tack.

Congratulations your boat is now tuned for those conditions! We have a base number from which to work.

Next time you go sailing in say 15-20kn of breeze start at #5 and retension the boat for the higher wind speeds. It will take more tension, but how much again depends on the boat. Probably in the range of 1-2 turns.

Personally I don't use a loose gague, because I don't care what the tension is, I use a set on machinist calipers to measure the distance between the rigging screws. This means I can always get back to my neutral numbers even if I forget how many turns I have added or taken off.

The average shroud tension for moderate breeze is going to be somewhere around 10-15% MBL is mentioned above, but I know boats that sail with tension as high as 35% and as low as 3% of the MBL of their shrouds.

For a more detailed look speak with a sail maker, North has a good write up, and PS Boat Clinic: Tuning the Masthead Rig - Web Only Article has a good one. Ideally of course your boat has been raced a lot and the class has a tuning guide for the boat. This is where tension gauges are great, because rig tension is the only way to exchange tuning numbers. 150lbs of tension on my J-22 is exactly the same as on your j-22, but 3.275" (stud to stud measurement) on my J-22 port cap shroud has no relation to yours.


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## Rob Patterson (Oct 22, 2015)

I have adjusted the tension on my standing rigging on the Coronado 23 MkII by centering the mast and fine tuning under sail. I was a little intimidated by the big boat's over-sized rigging but I now plan to proceed as described above - keeping the mast in column (except for pre-bend).


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## SanderO (Jul 12, 2007)

But there is no pre bend needed on fractional rigs where the backstay creates mast bend.


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## SanderO (Jul 12, 2007)

Barquito said:


> Nice write-up SanderO. One part I don't understand:
> 
> Wouldn't it make a huge difference, that the port and stbd shrouds may not start at the same length? Do you just center the mast after getting to the proper tension?


I believe what you want to do is hand tighten the turnbuckles... no leverage... until the mast looks to be standing vertical. That is the starting point to ramp of the basic tension to 15% breaking strength. If it starts as plumb straight it should be the same number of turns on port and starboard.


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## Stumble (Feb 2, 2012)

SanderO said:


> But there is no pre bend needed on fractional rigs where the backstay creates mast bend.


Um, I am not sure what fractional S you have tuned but as a rule they carry far more pre-bend and rake than a masthead rig. In large part because fractional rigs are far more prone to rig inversion than mast head rigs are. The additional prebend also makes it much easier to induce more bend in the mast with the backstay.

The upside is that fractional rigs generally also have swept back cap shrouds, which as they are tightened induces prebend faster than with a masthead and strait shrouds.


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## SloopJonB (Jun 6, 2011)

Get a Loos gauge or equivalent - it's the only way to get 15% on all the wires.

I've found 30% and 40% difference from one to another with the tightest being well under 15% when they "felt" the same and "felt" tight enough.

Some people recommend tightening keel bolts with a wrench with a piece of pipe on it and tightening the nuts "until the suckers scream". I prefer to use a torque wrench.

Same thing IMO.


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## SanderO (Jul 12, 2007)

I can only speak for the fractional swept back single spreader deck stepped Selden rig I have. The mast is rigged without pre bend and the bend is created by increasing the back stay tension. The mast is 51' tall.


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## Jaramaz (Aug 9, 2013)

SloopJonB said:


> Get a Loos gauge or equivalent - it's the only way to get 15% on all the wires.
> 
> I've found 30% and 40% difference from one to another with the tightest being well under 15% when they "felt" the same and "felt" tight enough.
> 
> ...


Oh Jon! Sailing is not an exact science, haven't you noticed?

A boat is a living thing laugh ), the total system of stays, mast, huss, deck ... can be seen as a set of springs. What is the point of adjusting one part of this system without having control of the others.

There you are trying to measure life. Oh well, good luck.

When sailing, cocking and in some other sports I do not measure. I am not doing these activities for the pleasure of measuring, I am doing them as I want to ... live.

To paraphrase I am now cocking dinner to my family and a bunch of guests. Measure? No, never. It will be what it will be.

Stay tension ... yes, after some few years I know quite exactly how it should be. I am sensitive enough. And adjust, if I want, during sailing, as described.

/J


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## RichH (Jul 10, 2000)

This is probably the most comprehensive rig tuning guide on the internet: http://www.riggingandsails.com/pdf/selden-tuning.pdf indeed a tension gage is needed; however, the information in this guide provides an alternative method using a 'meter stick' and an eyeball.

One of the secondary functions of a tension gage is to continualy monitor the rig for permanent overstretching (yield/deformation) of wire and components & including chainplates and their attachments. 
If you sail your boat 'hard' or very aggresively, you can also monitor the rig while underway in boisterous conditions to ensure that the rig tension doesn't exceed about 30% wire tension ... the point at which most stainless wire begins to stretch or permanently deform (depending on how much 'safety factor' the designer included in his/her design) and the point at above which the potential of future fatigue failure rapidly accumulates.

The following advice will allow you to 'properly' adjust backstay tension while underway and need to adjust for the wind strength encountered (a technical discussion or maximizing boat performance): http://www.ftp.tognews.com/GoogleFiles/Matching Luff Hollow.pdf


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