Dyneema for running back stay ?

[Jassira]

I'm thinking of replacing my running back stays with dyneema or similar, they are currently 10mm 1x19 stainless wire which has a break strength similar to 10mm dyneema or 16mm marlowbraid. She's a Bruce Roberts 53ft, 22tons, cutter rigged with a stay sail of approx 400sqft.
Any experience / opinions would be appreciated, thanks

 

[Seashoreman]

I replaced topping-lift with 4mm Dyneema during fit-out. It needed replacement so I thought I would try this for no particular reason. However, I have now obtained a loud and irritating vibration and audible note in any moderate wind. Might be a minor irritation but it goes right through the boat at night time.

 

[geem]

We had dyneema runners on my last boat. They were great and had less chafe on the sails. I cant see any reason not to go with dyneema but I would be tempted to go up to 12mm not 10mm for a boat of your size. the termination of the dyneema in a splice or knot will be the weak point, I suspect less than the breaking strain so going up a size will help.

 

[geem]

I replaced topping-lift with 4mm Dyneema during fit-out. It needed replacement so I thought I would try this for no particular reason. However, I have now obtained a loud and irritating vibration and audible note in any moderate wind. Might be a minor irritation but it goes right through the boat at night time.

slacken the mainsheet and it will go away

 

[MikeBz]

Be aware that if you are using uncovered dyneema then it has low UV resistance - so replace it often (or use wire...).

 

[Keen_Ed]

Actually, dyneema has good resistance to UV.

http://www.marlowropes.com/dyneema.html
"UV Resistant: Dyneema® has very good resistance to photo degradation, maintaining its performance when exposed to UV light"

It's PBO that has very poor resistance.

 

[Spirit of Glenans]

slacken the mainsheet and it will go away

+A little slack in the kicker.

 

[Seashoreman]

slacken the mainsheet and it will go away

Just remembered that's what I did on the way home. Good thinkin.

 

[langstonelayabout]

I'm thinking of replacing my running back stays with dyneema or similar, they are currently 10mm 1x19 stainless wire which has a break strength similar to 10mm dyneema or 16mm marlowbraid. She's a Bruce Roberts 53ft, 22tons, cutter rigged with a stay sail of approx 400sqft.
Any experience / opinions would be appreciated, thanks

Suggest you 'over engineer' with 12mm dyneema and also advise your insurance company that you have improved the materials of the standing rigging on your boat. Make sue they acknowledge this fact otherwise if there was any 'incident' involving the running backstays they might try and wheedle out of their position as insurer due to 'an unqualified person changing the design of the runners'...

 

[langstonelayabout]

I replaced topping-lift with 4mm Dyneema during fit-out. It needed replacement so I thought I would try this for no particular reason. However, I have now obtained a loud and irritating vibration and audible note in any moderate wind. Might be a minor irritation but it goes right through the boat at night time.

I did this too! Epic fail.

I'm about to replace the new 4mm topping lift with the old 8mm laid rope... :/ My missus complains endlessly about the whirring noise of the aliens landing nearby...

 

[langstonelayabout]

slacken the mainsheet and it will go away

Not on my boat it doesn't, and I've tried, oh how I've tried. I'm putting the old (read as: 'thick') topping lift back on.

 

[geem]

Not on my boat it doesn't, and I've tried, oh how I've tried. I'm putting the old (read as: 'thick') topping lift back on.

Do you have a stack pack? Tighten the stack pack and loosen the topping lift. Most stack packs will support the boom so there shouldn't be a need for much tension in the topping lift. It worked for me. We had the alien transmission thing going on for a while until I sussed out what it was!

 

[prv]

Not on my boat it doesn't, and I've tried, oh how I've tried. I'm putting the old (read as: 'thick') topping lift back on.

Well, on my boat the 10mm topping lift (sized to be a spare halyard or a safety line for going up the mast) also does the humming thing in certain wind conditions, so it's not just about line size.

Pete

 

[MikeBz]

Actually, dyneema has good resistance to UV.

http://www.marlowropes.com/dyneema.html
"UV Resistant: Dyneema® has very good resistance to photo degradation, maintaining its performance when exposed to UV light"

Hmm, that's not exactly a quantified measure is it. I'll bet that covered dyneema has a lot better UV resistance than uncovered, and that both have poor UV resistance compared to wire. Personally I wouldn't use anything but wire for standing rigging which is going to be outside all the time. YMMV!

 

[30boat]

Hmm, that's not exactly a quantified measure is it. I'll bet that covered dyneema has a lot better UV resistance than uncovered, and that both have poor UV resistance compared to wire. Personally I wouldn't use anything but wire for standing rigging which is going to be outside all the time. YMMV!

My Genoa halyard is 8mm covered Dineema and dates from 93.The bits that are in the sun (Algarve sun mind)are in perfect condition.I'd say it resists UV pretty well

 

[rwoofer]

I replaced the backstay on my RM with Dyneema and it performed faultlessly for the 3 years I had it.

 

[micha571]

I replaced our wire runners (5mm) with 6mm Dyneema some seasons ago and wouldn't change back. Just for caution, I make new runners every four years.

 

[MikeBz]

My Genoa halyard is 8mm covered Dineema and dates from 93.The bits that are in the sun (Algarve sun mind)are in perfect condition.I'd say it resists UV pretty well

The (polyester?) cover is protecting the Dyneema core. Generally using covered ropes for standing rigging is undesirable due to the windage. Uncovered Dyneema and Spectra do end to produce some strange humming noises when under tension.

 

[langstonelayabout]

Do you have a stack pack? Tighten the stack pack and loosen the topping lift. Most stack packs will support the boom so there shouldn't be a need for much tension in the topping lift. It worked for me. We had the alien transmission thing going on for a while until I sussed out what it was!

It can only be the Aliens! lol I've tried slackening off the topping lift and letting the 4mm lazyjacks take some of the weight of the boom/main and it did improve things to a point. Still, swapping to the old rope this weekend and better sleep/less bashed ears are on their way back

 

[Clive]

I replaced my single backstay with Vecrtran V12, 10mm on my X-yacht, Vectran is an uncovered Dyneema but is coaded to protect from UV. works fine, and was easy to splice, using a one of those hollow fids.

much lighter than wire and easier to do your self, although I did get "The Rig Shop" to make it up.