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Truce · 23-08-2020, 15:54

I am considering fitting a top down furler on my 36ft cutter to improve progress in light winds. I have a spinnaker that can be modified to suit. This will require fabrication of a prod but little other modification needed. The furler and swivel hardware I can purchase or modify existing bits at relatively low cost.

The high cost item (and key to the whole system) is the anti-torsion rope or cable as some people call it. I was wondering if anyone has come up with a method of producing a homemade anti-torsion rope using dyneema or similar? Is there any industry that uses anti-torsion rope that can be obtained at non marine prices?

I am in the fortunate position of being able to source cordage at cost plus, so if a viable homemade fix is available I may be able to save a few beer tokens. Looking forward to any genius ideas out there.

johnn33 · 25-08-2020, 04:25

Hi Do you have a Kim Holman 36? I do not know a Hohmann.
Interesting idea - perhaps you have already looked at Harken, and Doyle sails, and also https://info.upffront.com/blog/top-d...the-difference ?
John

Breaking Waves · 25-08-2020, 06:47

Back when code zero furling started, the solution was two (smallish diameter) dyneema lines in parallel (about 3" apart) up the luff. This created a decent size 'foil' for the sail to furl around.

It worked, we used it for several years. It is decently easy to DIY relatively inexpensive, but it is a bit more complicated than a single large diameter tight braid rope - it required dual pockets in the luff and spreader plates top and bottom.

For large diameter tight braid high modulus single line torque rope . . . .you are talking about something which is intrinsically relatively expensive. There are such ropes used in commercial applications but they are expensive.

**tkeithlu** · 25-08-2020, 07:05

One poster at this site suggests vinyl covered wire cable as a DIY top-down furler.

https://forums.ybw.com/index.php?thr...furler.390370/

mikereed100 · 25-08-2020, 08:14

I have used a loop of dyneema double braid that I sewed to the sail at intervals, much like what Breaking Waves describes above. As long as the halyard tension was tight, it worked pretty well.

Truce · 25-08-2020, 23:25

Hi, my boat is designed by Russell Hohmann. A Canadian Gentleman now living in New Zealand, for more info check https://truce.nz/yacht-truce/

Yes, I have visited the website you suggested - and a few more. Perhaps I should have specified that i am looking to fly the sail away from the anti-torque rope and not have a captive luff unlike a furling sail.

RaymondR · 26-08-2020, 00:53

As a single hander one of the more difficult sail handling jobs I take on is working a genaker. Love the sail and think your champagne sailing experience is downwind at 5-6 knots under twin head sails without any sort of following sea.

Consequently I have spent a considerable amount of time pondering in how to implement a DIY furler for the genaker and much of the pondering predates top down furlers.

One of the schemes I came up with was using lay flat hose as the furler foil.

I have used lay flat hose to pump water fairly long distances and one of the things I found intriguing about it was it's capacity to resist torsionally induced twisting when under pressure.

My scheme was to build the top swivel from nylon it being then clamped into the upper end of the hose. The lower end plug woild contain a schrader valve (from a push bike tube)

In the bag, and whilst being hoisted, the tube would be deflated. After hoisting the tube would be inflated prior to unfurling the sail, the luff of which is attached to the hose. I figured about 30 psi would be sufficient.

After furling the valve on the bottom would be opened to deflate the tube prior to stowing the sail in the bag.

I am now designing a top down furler and was considering how to implement the twist resistant halyard component a couple of days ago. What I have come up with so far is to experiment with taking say the outer braid from 14 mm yacht braid and threading it over 12 mm yacht braid thereby doubling the outer braid which is the more torque resisting component of the rope.

Truce · 26-08-2020, 04:11

RaymondR, thanks, you appear to have given this some thought - true out of the square thinking. I have no clue if your idea would work in practice and admit to being a bit sceptical, the trials will be interesting. But - maybe the physics will work out, you could be onto something. I will be interested to know the results.

Most rope manufacturers supply covers for their ropes, usually dyneema or similar. when ordering covers just go up a couple of mm in size. Maybe a couple of covers milked over the halyard and stitched on will provide some torque resistance.

Breaking Waves · 26-08-2020, 08:18

Quote:

Originally Posted by Truce

Perhaps I should have specified that i am looking to fly the sail away from the anti-torque rope

There is no reason the double dyneema cord system will not work for that.

Since you do not have luff pockets to help keep the dual lines spread, you would want perhaps 3 (I guess depending on length) light weight 'spreaders' up the system hold the two lines apart. You could use the same method people do to hold antenna wire away from backstay - eg small pieces of pvc pipe, with slots on each end for the cord wire tied at each end to the cord. These spreaders can/should be quite small and light - they will not carry much load - just there to hold the two lines apart when the system twists.

If you want to DIY the single thick line anti-torgue rope approach . . . . my suggestion would be to find a double braid with dyneema or vectran core with the tightest weave polyester cover you can find, and then coat the cover with one of the many anti-chafe plastic coatings (quite common in industrial applications - like https://www.industrialpolymers.com/p...uekote-series/ just as one example). You are ofc not worried about chafe, but this plastic coating will lock the braid together making it much more anti-torque. Bigger diameter here = more torque resistance. How much diameter you want to use would be a weight, windage and stowage tradeoff

An alternative to the coating is to cover the whole rope with adhesive lined heat shrink tubing which would also 'lock' the cover but i suspect would be less durable than the coatings (they are engineered for this which the tubing is not).

RaymondR · 26-08-2020, 23:46

I think the inflated tube idea would also work inside just the outer cover of braided line. The pre-stressing of the braid would serve to take any looseness out and thereby make it very twist resisting.

RaymondR · 23-03-2023, 03:48

This thread's a bit old but I've purchased a top down furler and am having trouble finding torsion rope and decided to carry out an experiment on DIY fabrication of torque rope. I purchased a couple of metres of 12 mm and 14 mm double braid and used the inner braid of the 14 mm to pull the 12 mm through the 14 mm's outer braid. It went easy and I was surprised at how much it then resisted twisting.

The reduction was so effective that I decided to use 10 mm Spectra as the inner core and the outer braid from 12 mm polyester double braid for the full scale test.

patmo141 · 30-03-2023, 09:37

Quote:

Originally Posted by RaymondR

This thread's a bit old but I've purchased a top down furler and am having trouble finding torsion rope and decided to carry out an experiment on DIY fabrication of torque rope. I purchased a couple of metres of 12 mm and 14 mm double braid and used the inner braid of the 14 mm to pull the 12 mm through the 14 mm's outer braid. It went easy and I was surprised at how much it then resisted twisting.

The reduction was so effective that I decided to use 10 mm Spectra as the inner core and the outer braid from 12 mm polyester double braid for the full scale test.

Can I get a picture of that?

RaymondR · 30-03-2023, 14:18

Quote:

Originally Posted by patmo141

Can I get a picture of that?

Hi patmo 141,

The experiment was successful and proved fairly easy to to implement and resulted in a surprising increase to the torsional rigidity of the 12 mm polyester double braid so I went ahead and purchased full lengths of 10 mm Spectra for the inner core and 12 mm polyester for the outer braid.

I cut back about 6 inches of the core of the Spectra and inserted the core of the 12 mm into it and stitched the end of the Spectra outer braid to the core of the polyester so that it would grip with the tension and make a smooth splice and pulled the Spectra through the polyester outer braid without any problems.

I then fastened the pulled through end of the Spectra to a rail and wearing a pair of riggers leather gloves worked the outer sheath along to the loose end until I had a fairly tight fit of the now outer polyester braid over the Spectra inner core.

Over 16 metres of both Spectra and polyester rope the "new" combined "triple braid" rope is now about 15 metres long, which is about the length I needed.

I'm busy on a couple of more urgent projects at the moment but will post some images as soon as I have some spare time.

RaymondR · 04-04-2023, 14:40

First trial for DIY torque rope.

It required quite a few turns before it started to furl but was successful in a no breeze trial. The field trial will be carried out early next month.