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  Topic Review (Newest First)
4 Weeks Ago 12:51 PM
RichH
Re: Tension of Standing Rigging

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/GoogleFil...f%20Hollow.pdf
4 Weeks Ago 11:21 AM
Jaramaz
Re: Tension of Standing Rigging

Quote:
Originally Posted by SloopJonB View Post
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.
Oh Jon! Sailing is not an exact science, haven't you noticed?

A boat is a living thing ( ), 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
4 Weeks Ago 05:13 AM
SanderO
Re: Tension of Standing Rigging

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.
4 Weeks Ago 07:29 PM
SloopJonB
Re: Tension of Standing Rigging

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.
4 Weeks Ago 06:34 PM
Stumble
Re: Tension of Standing Rigging

Quote:
Originally Posted by SanderO View Post
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.
4 Weeks Ago 04:51 PM
SanderO
Re: Tension of Standing Rigging

Quote:
Originally Posted by Barquito View Post
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.
4 Weeks Ago 04:46 PM
SanderO
Re: Tension of Standing Rigging

But there is no pre bend needed on fractional rigs where the backstay creates mast bend.
04-01-2016 02:13 PM
Rob Patterson
Re: Tension of Standing Rigging

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).
04-01-2016 01:42 PM
Stumble
Re: Tension of Standing Rigging

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.
04-01-2016 10:11 AM
Jaramaz
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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