Composite rigging

[topofthemorning]

Hi,
Has anyone used dyneema when rerigging?
What other components did you use?

[Phillip]

There may be a cost disadvantage in using dyneema against ss wire.

Check out Free Range Sailing on YouTube when they did a conversion to dyneema in Tasmania.
One thing to remember is that you will be constantly tuning your rigging due to stretching.

[steve]

I replaced the two lower parts of my backstay with 6mm Robline Ocean 3000 dyneema a few years ago.  It has given no problems, but no real advantages except probably lower cost.  I did the splices myself and then strained them by attaching each between a tree and my car's tow bar.  When installing them on the boat I cow-hitched them at both ends so I did not need any new fittings.

I also fitted a removable inner forestay using 8mm dyneema a few years ago.  It was just generic dyneema from a website.  I did the splice at one end, ran the dyneema up through the mast, over a spare halyard sheave and down to the deck. I then did the second splice.  The splices are too wide to fit through the slots on the mast so I could not take the stay ashore to strain it between car and tree.  Consequently it has taken a while to strain the stay in use and bed in the splices.  (The splices will initially be significantly shorter than the length of the dyneema they are made from, until they bed in.)  

At one end of the removable forestay I have a splice with stainless thimble, and a stainless shackle.  At the other end (at the bottom of the mast) I fitted a splice with a low-friction ring, with 3mm dyneema in a four part tackle down to another low-friction ring attached to the mast girder, and then ran the 3mm dyneema to a winch and cleat.

I don't think the removable forestay is as successful as the backstay for three reasons:-

A) It has stretched as the splices have bedded in.  Not much of a problem as the stay gets re-tensioned each time it is fitted, but would be more of a problem with standing rigging.  If you possibly can do, strain each stay between car and tree before fitting them.

B) It has gone hairy after being used in anger only twice.  This may be due to the old bronze hanks on my sail, although I did try to smooth off the hanks. (Obviously this would not be a problem with stays that do not have sails running up them).  Or it might be due to poor quality dyneema.  The Robline dyneema used in the backstay is showing no hairiness.

C) Running the dyneema up the inside of the mast, over the halyard sheave and down to the deck imposes a very high load on the sheave, the spindle it runs on, and the aluminium cheeks that support the spindle.  According to my elementary and possible incorrect calculations, the cheeks are the weakest part of my installation.  To protect the cheeks I am planning to put something at one end of my stay that is designed to break at 1 Tonne.

The Free Range Sailing videos that Phil pointed out are definitely worth watching.  They had the stays made up and fitted professionally and implied that there was no cost saving compared to stainless.  They had to re-tension the stays as they sailed, on a number of occasions if I remember correctly.

I replaced all my standing rigging last year.  I chose to use stainless wire, not necessarily because I thought it better than dyneema, but rather because I thought dyneema might reduce the resale value of the boat.

Steve