Using dyneema for rigging - warning

[Robert Sheridan]

We had a go with a dyneema bridle for our Tiki 30 at the suggestion of the rigger as it is hard to make up hard eyes on 6mm wire. The dyneema stretched really badly the first time out, we retightened and it stretched again (to such an extent I had to set up the spinnaker halyard as a forestay) so we are going to go back to wire.

We have since found out that there are forms of dyneema that 'creep' less than others, but it all creeps to some extent.  The stuff we had was apparently from Liros and the supplier is getting back to them.

So.. if you are thinking of using modern braids for rigging check their stretch and uv characteristics  very carefully before buying and also make sure you are supplied something with a cover to protect against abrasion.

[paul anderson]

So long, i have also made up synthetic rigging, but was able to do it with fse robline a European product.I used the old stainless steel heart eyes, a lot cheaper and they do the same job, nicht waar?

[kim whitmyre]

SoLong,

What type of masthead connection, loops at top of shrouds (Wharram-style), or metal tangs? Need to know first.

Kim

SoLong said:

HI Kim,

I want to replace my standing rigg by dyneema/dynex. I already contacted Colligo Marine, but there was no feedback. Wich parts of colligo do you use? I want to use the same on my tiki30. Whow long is your mast and how wide is your boat how long are your shrouds? I have a roller jib. So I only want to replace the two wires to the bows under the forstay. How did you fit the colligo-units tu the u-bolts?
 
kim whitmyre said:

Robert, Colligo Marine has several .pdf files on dyneema/dynex dux splicing and rigging. Here's one on the basic eye splice for 12-strand braid, called a modified Brummel Splice: Brummel Instructions

Near the end, #17, are the guidelines:  "You can expect about 2 inches of stretch for 7mm and 4 inches for 9 mm to reset the  line braid."

 

As always, get some extra line to practice with, and do some measuring as you go to see how the length changes after the braid resets.

 

[SoLong]

wharram style, because it is still a wooden mast. there has to be the same eye in the shrouds. but I think, it is no problem to splice it.

[kim whitmyre]

SoLong,

Here is a shot of the "boat end" of one of my shrouds:

The upper deadeye Colligo refers to as a "line terminator," the lower deadeye Colligo refers to as a "chainplate distributor."

Colligo offers charts for sizing the fittings to the loads of your rigging. To size the dyneema line, use the working loads of your existing wire to compare to the working loads of the dyneema line. In my case, I am using 1/4"/6mm dyneema which has over twice the strength of the previous 3/16"/5mm wire rigging.

I want to replace my standing rigg by dyneema/dynex. I already contacted Colligo Marine, but there was no feedback. Wich parts of colligo do you use?

Vaea is a tiki 26, so the mast and the shrouds are no doubt shorter than your tiki 30. Mast is 27', beam is 14 1/2'. Just use your existing rigging for the working length; the synthetic shrouds will be shorter than this measurement to compensate for the re-setting of the braid that is disturbed by the work of splicing. I played it safe and made my shrouds around 12"/300mm shorter. You then have enough distance between the deadeyes to run your lashing in order to tighten the shrouds. You don't want to end up with the fittings too close together!
 I used plain dyneema for my shrouds, and used dynex dux for the forestay.  I used sailmaker's one piece thimbles in the bridle eyesplices; a Wichard forged shackle joins the bow eyes to the bridles:

A larger Wichard shackle joins the bridles to the forestay.

I want to use the same on my tiki30. Whow long is your mast and how wide is your boat how long are your shrouds? I have a roller jib. So I only want to replace the two wires to the bows under the forstay. How did you fit the colligo-units tu the u-bolts?

 

Yes, the upper shroud eye is no problem to splice; do put a chafe-sleeve on the eye to extend the life of the dyneema.

[paul anderson]

This is how I made my shrouds with leather anti chafe.

[kim whitmyre]

Looks good, Paul!

[SoLong]

Thanks for the information!

[laurent]

Hello,

what is the resistance of shrouds preconised by Haneke for Tiki 26  . I dont find that on my plans ?

thanks

[kim whitmyre]

Laurent,

Off the top of my head, the wire rigging specified on the plans is 750-800 lbs working load.

Kim

[laurent]

Hellooo, i just made it my self, the first one, dont laugh, i discover every tool, i am not handymade . From a sheet of Darlin or POM C bough on Ebay for ten € . Exist in black , better for UV . i cut it with hacksaw, then a sand disc on a drill, then a grinder with disc for metal for the groove( be carefull !)i will done the same way for the chain plate terminator . It is very easy and fast . The hole on top is unnecessary . The friction with dyneema is perfect . i used 4mm = 1300 kg .

[Tam Dl]

They make sandpaper in a lace form that you can just saw back and for in the hole to make it tail out nicely.  i think the company might be mitchel, but you can make your own, just roll some epoxy coated lace in some course SC valve compound.  with plastic you can melt it if it stays upwind.

The techy way to cut the ends if you don't go CNC is to find the pivot point in your block, and secure it to a rotary table, or just use a pivot point in the piece.  You run the end mill right up the track, then swing it 90 degrees into the block, do this from both sides.  If you have it in a mill with a rotary table, you can cut the races in aluminum.  For wood a good choice is diamondwood of the fully impregnated type.  For a router wood set up, just attach a vise to some wood, and make sure the pivot bolt is in line with your pivot point on the block.  Another option is to mold something out of composites.

[Ian R]

Re Dyneema. I am making up rigging just now for my boat (Tiki 31').

I bought a reel of Marlow DKMax SK 78 last year. I was planning to use a steel forestay with roller reefing, the synthetic stuff for the rest. Somehow the new sail I had made for that disappeared in my multitudinous moves (who wants to nick a sail? bizarre) . So I have picked up another jib - hanked on, the roller reefing will have to wait. I may use a synthetic forestay, but have the gear to make a steel one myself if I want, can't decide.

I have 6mm synthetic Marlow. I am making deadeyes just now. I bought some CARP Tufnol as an offcut for that  (very expensive engineering grade) and have sawn 8 blocks out of that by hand with a thin Japanese ripsaw (the best handcut for that).

I have made a prototype block based on calcs I have read elsewhere, by hand. Chisel and saw and file.

I think it took about 2 hours all told, but I have laminated an elm tail onto the deadeye, for the tail as it takes no pressure and my eight blocks from my cheap offcut only made the main part of the deadeye.

I've got wych elm I sawed from the trees and kilned myself 20 years ago. I'd make the blocks out of that really, but I suppose I have to use the best available which is CARP Tufnol. Originally blocks were all made from elm, as it resists splitting. Therefore it was used for wheel hubs on carts and carriages. I have used it for blocks elsewhere.

Blocks by Colligo seem to be £60 environ. I think mine will be stronger!!

Any views on Dyneema (sic) forestays? Can I hank on to this without abrasion problems?

I don't do photos or tech stuff, have gone country,  but may get someone else to send one up here sometime.

I'm using 6mm  Marlowe. 6 mm thimbles for the top end seem up for chafe on the sides, so I am using 8mm thimbles for that.