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post #21 of 42 Old 08-04-2015
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Re: Rig tension too tight?

There are really no hard and fast rules of strictly "BY THE NUMBERS" for rigging, other than

1. the rig provides a stable platform for the 'shaping' of the sails
2. The mast remains in a relative 'straight column' ... as a platform for the sails. (Although, there are rigs that are purposely built as 'bendy'.)
2. the stretch (sag) of the rigging wire (forestay, etc.) provides a predictable structure to which one attaches the headsail. Sail design, especially the wind-loaded headsail, is cut/designed based on the predictable stretch/sag of this wire.

What this means is that typical rigging, may have material strength/stretch characteristics that falls on one extreme end of 'the specification' especially and importantly it's 'elasticity'; and, to set up for optimum/maximum performance of the sails (due to their spread of tolerances/dimensions due to variability of the cutting/design and variability in the sail fabric material strength characteristics, etc.), that the rig and its set tension may have to be varied so that the sail characteristics MATCH the structural/elastic rig characteristics for the range of windstrengths as based on the design. TWO independent 'systems' that must be adjusted so that they 'work' in concert with each other.

All 'the numbers' are based on averages - average stretch of the wire, average stretch of the sail fabric ... when wind-loaded; and, sometimes the way that all these 'averages' stack-up, one may have to operate such tensions at outside of the 'averages'. Unless specified otherwise, such as for high end racing, etc., the typical sail will be designed for use between 12-18kts of windstrength. On either side of this 'normal' (15% of wire tension or less than 10kts. or greater than 15-18kts) the precise sailor will have to make adjustments in rig tension (typically backstay), sail (edge - luff/foot/leech) tension, etc. etc. etc. etc. The precise sailor wishing for 'maximum' output and a high level of performance usually will make such 'adjustments', sometime beyond 'normal' to achieve this goal. If you're not going to set up these tensions yourself, find a rigger who is also a sailmaker or vice versa!!!!!!!!

An Example: The 'usual' situation where rig tension (usually backstay, etc.) should be adjusted is when operating at or above the maximum 'design' condition parameters - beating in 18+ kts of wind and where the rig stretches in dimensions ..... and now a large sagging curve develops at the luff of the headsail (a big curve in the luff to rearward and to leewards) .... such changes the angle of attack which decreases ability to 'point', the leewards sag promotes aggressive heeling, slows the boat due to increased sail draft and hooked up leech, and promotes the boat to be now start skidding off to leewards because the sail went 'draft aft'. The solution: change to smaller jib, or tighten up the backstay, change the 'edge' tension on the sail, less sheet tension, etc. etc. BUT not to increase the tension so that the rig exceeds 'yield' (typically above 30% tension in 'some' member) or the rig will be in danger of breaking.
If you want to continually be at the top of your racing game, record all the tensions vs. windstrengths, etc. ... especially when you 'won' and when you 'lost' - do not 'guess'.

Here's an article that I wrote many years ago which discusses the phenomenon of sail shape vs. rig stretch (rig tension). This article was written for cutter/solent rigs which have 'very complex' stretch characteristic due to the 'interplay' of two headsails; but, the principals will apply to simple 'sloops'.
Rx: set your rig tension so that the shape of the sails, especially the luff curve of your headsails, closely matches what the sailmaker designed into the sails, AND that the rig tension does not routinely exceed 30% when the boat is at maximum heel when in 'high' wind ranges. (in 'blammo/survival' conditions when on long passages, my tension meter is mounted ON the backstay - tells me WHEN to reef down or change to a smaller headsail, etc.): http://www.ftp.tognews.com/GoogleFil...f%20Hollow.pdf

15% is the 'usual' starting point for rigging ... for Sailmakers too
Hope this helps.
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Last edited by RichH; 08-04-2015 at 10:36 AM.
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post #22 of 42 Old 08-04-2015
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Re: Rig tension too tight?

Quote:
Originally Posted by Holland View Post
The point i was trying to make is if you have a rigger check the rig prior to a long voyage and your rig is not readily adjusted at sea then the rig should be set for the worst weather you may encounter, unless you are ready to go on the poop deck with spanner and screwdriver in a strong gale.
A very valid point but I don't plan on heading offshore on my old Hunter 31 project boat.

Actually I won't even be out of sight of land unless the fog rolls in.

I'm more concerned with ensuring the various stays are equally tensioned vis a vis their opposite numbers and that none of them individually are too loose or too tight. The rig is pretty close now and works fine - I just want to check it out with my Loos and touch it up if and where necessary.

I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.

Last edited by SloopJonB; 08-04-2015 at 10:47 AM.
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post #23 of 42 Old 08-04-2015 Thread Starter
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Re: Rig tension too tight?

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Originally Posted by overbored View Post
head stay is adjusted to length not tension this sets the amount a mast rake to control the amount of weather helm. the back stay is adjusted to set the headstay tension which controls the amount of headstay sag. head stay sag needs to match the amount designed into the headsail.
Sail the boat first and see how it sails it does seem the rigger knows what he is doing.
I sailed the boat from the yard (rigger) on a super gusty day. It seemed to sail fine, though it's hard to say given the conditions. My concern was not performance, but what appeared to be an excessive amount of tension on the rig (as per Loos). The rigger had a young guy that works for him tune the rig, and I find it interesting that the rigger never questioned that the rig was too tight in his response.

Guess I have to loosen everything and start from scratch. Not the end of the world, but not exactly what I had in mind when I paid a "pro" two grand for new rigging!

By the way, I tested my gauge on several other rigs around the marina and they tested within range for wire size. So the gauge seems OK.

Last edited by L124C; 08-04-2015 at 02:28 PM.
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Re: Rig tension too tight?

I just read an article on this well seemed more like a whole course on how to adjust the rigging to the right tension. There were 12 steps to go through. HE KEPT GOING BACK TO FOLLOW BOAT MANUFACTURERS RIGGING TENSION REQUIREMENTS. He also suggested using the Loos gage.

This is where I am at--where do you find that info on a 30 year old boat--I have been unable to find the info for a 1981/82 US25.

loosnaples.com has a chart if you do not have the sail makers specific requirements.

Last edited by katiejai; 08-04-2015 at 10:31 PM. Reason: added information
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post #25 of 42 Old 08-05-2015 Thread Starter
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Re: Rig tension too tight?

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Originally Posted by katiejai View Post
I just read an article on this well seemed more like a whole course on how to adjust the rigging to the right tension. There were 12 steps to go through. HE KEPT GOING BACK TO FOLLOW BOAT MANUFACTURERS RIGGING TENSION REQUIREMENTS. He also suggested using the Loos gage.
This is where I am at--where do you find that info on a 30 year old boat--I have been unable to find the info for a 1981/82 US25.
loosnaples.com has a chart if you do not have the sail makers specific requirements.
I could be wrong, but unless you bought a super high performance boat 30 years ago, I doubt the manufacture provided any specs other than the sail plan. Sounds like the author of the article might be an attorney!

I think Rich H is probably right, that there are no hard and fast rules, and it's probably as much art as science.

When I first bought my 30 year old boat, she had excessive weather helm on Port tack. I used a little book on rigging by Ivan Dedekam "Sail and Rig Tuning" to tune her, fixed the problem and she sailed great. Never once does Dedekam mention manufacture's rigging tension requirements.

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Re: Rig tension too tight?

There is something definitely wrong with this rigger or the guy he has working for him. When I picked the boat up, I asked the assistant why he ran the backstay aft of the stern rail. He replied "Well, it touches the rail either way and that seemed like the best way to rig it.". Later, I noticed a 3/8" gap between the top of the chainplate and the stern, which led me to notice the backstay was bending over the top of the stern rail, essentially making it part of the rigging (with all the tension mentioned in the OP!)

The first pic shows the way the rigger had it. Not a great shot, but notice how the backstay deflects over the rail and you can only see half of the turn buckle. The second pic shows when I moved the backstay forward of the rail. I'm no rigger, but the second line is so much more natural and obvious, it's laughable! The backstay barely kisses the rail, and the chainplate is against the boat again.

Funny thing is...this rigger is well known, has a big shop, and I have no doubt he works on boats who's spreaders are worth more than my entire boat. I guess he just wasn't interested in my little project and delegated it to his assistant who apparently doesn't have much common sense.
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backstay as rigged by hansen enlarged.jpg   backstay after.jpg  

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Re: Rig tension too tight?

That backstay should NOT be touching the stern rail ... as when the rig stretches due to boat pitching or the variably loaded forestay due to wind pressure on the jib/genoa, etc., ultimately being this close - will cause the backstay to 'saw' against the rail and will/can cause the stern rail to receive force from the backstay - eventually 'something' will have to 'give'. Id contact the rigger and ask for correction.

A change in mast rake is needed to change this backstay angle. With the mast probably now raked 'more aft', you're probably going to experience a bit more 'helm pressure'/weather helm. FWIW - so-called weather helm can be 'adjusted' by changing the (woven dacron) mainsail luff tension by halyard tension (up or down), etc.

If you decide to make the corrections yourself ..... a repeat of another posters very good recommendation for one of the very best rig tuning guides available on the internet (including how to correctly set up a rig without a tension gage using the 'meter stick method'): http://www.riggingandsails.com/pdf/selden-tuning.pdf
Again, Id contact the rigger and ask for correction.
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Re: Rig tension too tight?

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Originally Posted by RichH View Post
That backstay should NOT be touching the stern rail ... as when the rig stretches due to boat pitching or the variably loaded forestay due to wind pressure on the jib/genoa, etc., ultimately being this close - will cause the backstay to 'saw' against the rail and will/can cause the stern rail to receive force from the backstay - eventually 'something' will have to 'give'. Id contact the rigger and ask for correction.
As I indicated, they not only had the backstay "touching" the rail, it was basically hanging off the rail. Enough to deflect the (rather substantial) chainplate 3/8" aft. Anybody who doesn't have the common sense to realize this is wrong won't touch my boat again! The correction I'll be seeking will be financial.

Quote:
Originally Posted by RichH View Post
If you decide to make the corrections yourself ..... a repeat of another posters very good recommendation for one of the very best rig tuning guides available on the internet (including how to correctly set up a rig without a tension gage using the 'meter stick method'): http://www.riggingandsails.com/pdf/selden-tuning.pdf
Just reviewed the link. Excellent resource. Thanks to all!
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Re: Rig tension too tight?

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Originally Posted by casey1999 View Post
Too much tension could deform your hull, and anything over 30% can lead to yielding of the wire under sail, which means the wire should be replaced. Also note 304 stainless has a higher breaking strength than 316 ss, so tension, if going by % of breaking strength is different for same size diameter wire.
With the ridiculous tension the "rigger" put on the wires (remember, they were well off the 1/4" Loos chart), could this mean my new standing rigging is toast?
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Re: Rig tension too tight?

It appears to me that the hardware the pin goes through (Shackle?) on the shrouds may be too wide for the chainplate. I would think allowing that much play (at least 3/8", probably 1/2") at the pin could be problematic, creating uneven loading on the pin. I notice they used nylon spacers on the backstay, and it had a lot less play than the shrouds in the picture.
The old rigging was much narrower, allowing a gap of about 1/8" overall. Is this an Issue? (Sorry...now everything is suspect!)
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Last edited by L124C; 08-07-2015 at 12:45 AM.
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