Rigging, strength and flexibility

[Gargleblaster]

I had some two year old rigging fail on me this year in mid Atlantic. The 6mm 1x19 s/s wires broke at the swage connection through overflexing. Having read and watched some of stuff put out by the Pardys on heavy weather sailing I am thinking about talurit fittings on my replacement wire. I have done a search on YBW forums and read what everyone has said about them in the last 12 months. However and this is where I feel I am going to be shot down in flames, I would like more strength in my rigging and am considering Dyform rather than increasing to 7 or 8 mm 1x19, which could mean new fittings on the mast. I have already mentioned this to my normal rigger, but he doesn't want to buy in the Dyform especially for me and doesn't know if he can bend it.
I was wondering if anyone had any experience of talurit fittings with Dyform rigging?

 

[Guest]

Could you elaborate on the "overflexing". How did it flex at that point?

 

[BAtoo]

The main way I know for rigging to flex is if its not tight enough.

 

[Gargleblaster]

I normally keep my rigging quite tight. However during a storm I believe either my rigging stretched or my boat bent allowing the rigging to become quite loose and allowing I presume a lot of rattling at the swages on the rigging. I tightened the rigging once the storm had died down to F7. But 3 more gales later and my rigging was loose again and my stbd inner shroud was broken at the swage at deck level. It may be stretching as I look at the stbd cap shroud that is still standing and there are striations obvious [that is individual strands of wire are different colours of silver and one has a brownish tinge] in the wire between the cross trees and the deck.

 

[Guest]

I would do a full investigation of the reason for the loosening of the rig before I changed the wires.

The first thought is the mast step compressing. The chain plates next. If you still have the wire then get it checked. My rig has odd colour wire in it as well, nothing wrong with that.

At the time of the first stretch did the lowers and upper go loose or just the lowers? What about the back stay?

Was it possible that when your rig/boat flexes the lower chainplate attachment could fall out of its good position and can catch so the force as it sprang back was much higher than normal. U bolt chain plates normally have cross piece high up like an "A" to stop it falling out of the top position.

Whatever is the cause and whatever wire swage etc. you use, there will always be a point that they will flex in preference to the rest. Stopping the flex due either to bad alignment, lack of freedom of movement, or slack rigging is the most important part.

 

[dratsea]

I have put 13mm dyform into a Norseman swageless, harder work that ordinary wire and you need a special cone but it does fit together. Why does your rigger want to bend the dyform? One last question: did the wire break at top end or bottom end and what set up did you have at that end to allow movement in both planes at right angles to the wire?

 

[Anchorite]

Further to Dratsea...

....who is first to mention (implicitly) toggles: toggles top and bottom are standard good practice - or has this gone out of fashion. What was the set-up on your rigging?

 

[savageseadog]

I'd forget about Talurits, I would use Norseman/sta lok or a swage.

 

[Gargleblaster]

I don't know the norseman terminal although I have experience with stalock. I want to bend the Dyform as I would like to use it with Talurit fittings, but my rigger is not keen on either the Dyrofrm or the Talurit that is why I am seeking to see if anyone has done it. The wire broke at the bottom end. The fttings at the bottom end of the shrouds are closed bottle screws with forks at both ends and at the bottom attached to the chainplates using a toggle. The chainplates are also set up so that they lie beam to beam and allow movement in that plane, rather than fore and aft as I have seen other chain plates.

 

[savageseadog]

You can't bend 1 x 19 type wire in that fashion, it will break!

 

[Gargleblaster]

You are right about the mast compressing. It is deck stepped and during the storm I could hear the compression post creaking everytime I lay over to 60 degrees on the top of the waves. There are now stress cracks in the fibreglass where the mast is stepped. I can't do much about that without replacing the compression post which would proably require the fibreglass being cut out around the mast to do so.
I've described in another post the fixing of the shrouds to the chainplates. The chainplates themselves are welded to 3'foot long s/s straps that are fixed either side to a 2" bulkhead with about 20 bolts each. There has been no apparent movement in the chainplates.
What I'm trying to investigate is the possibility of both strengthening my rigging, reducing the possibility of stretch and making it more flexible so that in that situation again there will not be the stresses on it that has caused the wire to break.

 

[luddites]

Hi, 6mm 1x19 is the max size you can use for talurits because of the very tight turn required around the thimble. I have never heard of Diaform being used with talurits but the same would apply, and probably not even up to 6mm.
So if you use above 6mm talurits are not an option, although in my expierince they are very reliable up to this size and also easily inspectable for any movement.
You can use 7x7 in larger sizes with talurits because its designed to be much more flexilbe but you might struggle to finds a rigger who can do the larger sizes.

 

[stephenh]

See previous posts.....

I think you will find that Talurit can be ( and is ) used up to 50mm dia. ( on cranes, tugs, fishing boats etc.)
6mm is not the largest and there is a large selection of thimbles, not just the small o/a dia. ones that the average rigger sells.

The average rigger does not have the ( expensive) machines to use the larger sizes.

 

[dratsea]

Agree with rigger and savageseadog. I think you will be pushed to use 1x19 round a thimble. Dyform is stronger because the wires are trapezoids rather than round so there is less "wasted space" in the wire (30% from memory). From my limited experince with 13mm it is much stiffer than 1x19 of same size and even if you had a big enough thimble for 1x19 I think you will find that the dyform would not go round the same thimble.

I keep a couple of lengths of emergency rigging wire ending in talurit eyes. For 8mm I had to use 7x19 to get it to bend round an appropriately sized thimble. I hope it will work in an emergency but guess that even with the relatively small eye I have used it will still tend to deform under load and that would not be a good idea for permanent standing rigging.

Lastly I am not sure that I fully understand how the bottom ends are rigged but if the forks on the bottle srews fit tightly to the link below you may not have enough movement in the fore and aft plane. I guess the middle of the mast flexes more in fore and aft plane than side to side which might account for flexing at the swage. Should be possible to add an extra link at this point. Perhaps change bottom section of bottle screw to "T" or keep the fork and add in an extra "T" link.

 

[luddites]

Yes, that's what I said, provided you use wire of the right construction ie with sufficient small strands to be flexilble enough for the tight turn around the thimble, there is in theory no limit to the size of talurit which can be used, but to get wire of comparative strengh the diameter becomes too large for most yachts and the wire too heavy, so the average yacht rigger won't do above 6mm. Those involved with big trad craft where weight aloft and size is not such an issue will do it though.

 

[30boat]

You don't mention toggles as another poster said,and they are absolutely indispensable.Also if your compression post is not man enough for the job you do have to beef it up one way or anoter.

 

[rob2]

My understanding is that a talurit eye is not good under high strain and anyway the eye would be enormous to take 6mm wire! The geometry of a talurit eye is assymetrical and so puts a shear load on the wire at the end of the ferrule, this will work harden and fail under severe loads. Toggles are the most important feature in the alignment of the rigging and Norseman/Stalok fittings are not so prone to breaking as swaged fittings. Also Norseman/Staloks can be remade on board if repairs and jury rigging are required.

However, until you sort that compression post out, the uncontrolled load/unload cycle you're putting your rigging through will break anything you use! Having said that, you may not have such an insoluble problem as it first appears. Firstly it is important to ensure that the ends of the compression post are firmly supported and in good contact with the deck and hull. Don't assume that the bit under the glassing over is OK, you need to see the wood directly transferring the load between deck and hull. Once that is sorted, you might consider "encasing" the post by fastening two pieces of fairly stout angle iron around it. That will increase its rigidity and therefore stop the flexing which has been changing your rigging geometry. Another alternative would be to consider extra bracing at the centre of the post, again to reduce flexing.

Best of luck!

 

[luddites]

Not sure what do you mean when you say "the eye would be enormous to take 6mm wire?" 6mm is commonly used with talurits and is the max size when 1x19 wire is used but even at 6mm the strands will sometimes be found broken where they pass round the base of the thimble. Where larger talurits are used different construction wire with more numerous thinner strands is utilised in order to cope with the tight turn around the thimble.

With any conventional rig maximum articulation is number one closely followed by tension. For example when a boat is rolling heavily and the shrouds go through cycles of slack/tension if the wire is slack in the first place premature fatigue will occur where the flexilbe wire enters the neck of the solid terminal, becuase the slacker the wire the larger the movement taking place is in each cycle. Ditto upper stainless steel terminals which engage in mast keyholes and are often jammed against the extrusion wall inside the mast, so as the terminal body does not follow the wire in a good fair line, these are commom and account for numerous rig failures.
Agree about Norseman/stalock, probalby the most reliabe of all types and inspectable.

 

[Guest]

"...are closed bottle screws with forks at both ends and at the bottom attached to the chainplates using a toggle. "

That sounds right. As for the mast post we had to do work on ours due to the compression of a plywood spacer above the oak post.

We removed the mast base and the burrowed down to the oak in an area of 2x3" only. We replaced it all with epoxy bonded Tufnol sheets (first layers screwed to the oak post to keep the post aligned) and then added a load spreading layer under the mast base.

There is no sign that job was done as the rest of the fibreglass is absolutely necessary for the sideways forces.

But the key is to find which bit is moving and so since the rig is up I would start investigating what happens when the rig is tightened. Does the post move relative to the keel or does the mast base move relative to the post. I assume there is a mast base bolt coming through into the cabin. Or does the keel stay exactly the same distance to the mast base but the chainplates rise. You need some steel tubes that can be cut to length and a way to measure gaps. I used to be able to jam the heads door by tightening the rig. About 1/4" movement in the deck head. No problems now.

 

[rjp]

Talurits used to be quite standard for a wide range of wire sizes. I've recently replaced all the rigging on a 30+ year old boat that I've been renovating and there were talurit splices, probably original, at the top ends of all the shrouds - and the eyes were quite compact! Bottom ends had swageless fittings of uncertain origin. Interestingly only one Talurit eye had a couple of broken strands around the thimble - this with 1/4inch 1x19 SS wire. It did make me wonder what all the bad press about Talurit was about. I needed to remove a swageless fitting from a lifeline and found that the lock nut disintegrated as soon as I applied any force to it, and the cone was half corroded away, so even these have a finite life.

John