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tagster 06-18-2007 05:36 PM

Tension of Standing Rigging
 
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?

Valiente 06-18-2007 06:28 PM

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

sailingdog 06-18-2007 08:30 PM

Quote:

Originally Posted by Valiente
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.

Quote:

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.

Valiente 06-18-2007 11:46 PM

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.

tagster 06-19-2007 06:14 AM

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.

James Kenyon 04-01-2016 06:27 AM

Re: Tension of Standing Rigging
 
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

chuck5499 04-01-2016 07:28 AM

Re: Tension of Standing Rigging
 
Quote:

Originally Posted by tagster (Post 157578)
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.

SanderO 04-01-2016 07:56 AM

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

Barquito 04-01-2016 09:43 AM

Re: Tension of Standing Rigging
 
Nice write-up SanderO. One part I don't understand:

Quote:

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?

Jaramaz 04-01-2016 10:11 AM

Re: Tension of Standing Rigging
 
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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