Halo
Well-Known Member
Does anyone know what material jack stay webbing is ? I can get 50m of 25mm polypropylene webbing for £9 and make up my own or pay £60 + delivery for 2 x 10m ready made jackstays.
Jack Stay Webbing
- Thread starter Halo
- Start date
[163233]
...
Polyprop dissolves in sunlight doesn't it? I think they make vampires from it.
Jimmy Green does polyester webbing which should survive better.
Jimmy Green does polyester webbing which should survive better.
jwilson
Well-Known Member
AFAIK it is dacron/polyester but hopefully a fairly UV-resistant version of the basic material. I would not use polypropylene. Your boat - you using it - your choice.
Bobc
Well-Known Member
Get them ready-made from Jimmy Green.
It's really not worth the arsing about.
It's really not worth the arsing about.
MM5AHO
Well-Known Member
They're not difficult to make, if you have a suitable sewing machine. But choose the material carefully. There's various chemistries, most unsuitable, various thicknesses (what breaking strain do you need?), and consider the thread used to sew. And what will you sew on the end? Loops?
PetiteFleur
Well-Known Member
NEVER use polypropylene - it rots quickly in sunlight and it's nowhere as strong as Polyester or Nylon webbing. As suggested get from a recognised supplier like Jimmy Green(other suppliers are available) or your local sailmaker. You can also buy ready made jackstays with one adjustable end to adjust to your boat(forget the name). You can get Polyester webbing from people such as Kayospruce or others.
MonniotC
Well-Known Member
+1
lw395
Well-Known Member
I was looking at some webbing lifting slings the other day.
Available in quite high strengths at quite low prices.
Available in quite high strengths at quite low prices.
Plevier
Well-Known Member
https://www.cygnus-sails.com/item-Polyester_25mm_3000Kg.html £1.20/m is what I used (I think from memory offshore regs call for 2000kg min but could be wrong)
or
https://www.cygnus-sails.com/item-Polyester_25mm.html is 1500kg rating 65p/m
or
https://www.cygnus-sails.com/item-Polyester_25mm.html is 1500kg rating 65p/m
duncan99210
Well-Known Member
Just made up new ones for the boat. I used 25mm polyester webbing with a breaking strain of 3000kg from Point North here https://www.profabrics.co.uk/products/traditional-jackstay-webbing?variant=5940932291. I stitched it using V62 using the stitch patterns suggested in various websites on the topic. One loop on the forward end, the other goes to a propriety stainless steel buckle.
lw395
Well-Known Member
Are you sure the buckle is not a weak point?
alteredoutlook
Well-Known Member
They are a bit cheaper at force 4 - although they come in limited lengths
MM5AHO
Well-Known Member
Nylon doesn't have as good UV resistance as polyester.
Daydream believer
Well-Known Member
Bought webbing once & it disintegrated. Now I uses marlow braid on braid rope & splice 2 ends & pass it from the aft end to the bow & back down the other side. At the bow, where it crosses over, there is a large piece of slack to make a hand hold. The colour is flourescent orange to highlight it as a safety line. Being fairly soft it does not roll under foot like wire does ( i had wire once & that is very dangerous)
Yngmar
Well-Known Member
It's polyester. I bought mine here: http://www.ptwinchester.co.uk/25mm-polyester-jackstay-webbing-3000kg/
For the strongest way of sewing the loops, see the research Evans Starzinger did (probably have to visit archive.org for it now). I followed his advice and then covered the stitches in some green/red taffeta to protect the thread from UV damage. Beware though, my sewing machine nearly choked on sewing through three layers of the thick webbing (loop plus reinforcement strip as per Starzinger's page). They're holding up fine so far.
They're cow-hitched to the inner forestay chainplate on the foredeck and lashed to the aft mooring cleats with some Dyneema. No buckles or shackles. They run well inside the shrouds across the coachroof, giving us a better chance to not dangle over the side and drag in the water when we fall.
For the strongest way of sewing the loops, see the research Evans Starzinger did (probably have to visit archive.org for it now). I followed his advice and then covered the stitches in some green/red taffeta to protect the thread from UV damage. Beware though, my sewing machine nearly choked on sewing through three layers of the thick webbing (loop plus reinforcement strip as per Starzinger's page). They're holding up fine so far.
They're cow-hitched to the inner forestay chainplate on the foredeck and lashed to the aft mooring cleats with some Dyneema. No buckles or shackles. They run well inside the shrouds across the coachroof, giving us a better chance to not dangle over the side and drag in the water when we fall.
thinwater
Well-Known Member
I've done all manner of testing for mags. A few points:
* If you are going to sew your own, in addition to using UV-proof thread, sew a bit of the pattern--just a dozen stitches--and then break one under body weight or similar. Only then will you actually know what YOUR machine is doing. They can just as easily be hand stitiched with whipping twine. Very durable. Again, sew a few stitches and then break it. Then calculate the stitching required to reach the strength of the webbing and triple it. If this sounds like too much work, buy them.
* If you were making a tight rope 10 feet long and one 100 feet long, would you use the same cable? I doubt it, and you know why. So why assume the webbing is the same for all boats? the OSR says 4500 pounds, but if the boat is longer than ~ 35 feet and you use something stronger, with less stretch, the requirements go up. I once ripped a 4500-pound SS jackline off a boat with my hands; he forgot about the tight rope effect on forces.
Think about how much defection at the mid point you are willing to live with. But the less deflection, the greater the stress. I've used nylon rope, polyester webbing, and Dyneema rope covered with webbing. In each case the materials was chosen to fit the boat.
* If you are going to sew your own, in addition to using UV-proof thread, sew a bit of the pattern--just a dozen stitches--and then break one under body weight or similar. Only then will you actually know what YOUR machine is doing. They can just as easily be hand stitiched with whipping twine. Very durable. Again, sew a few stitches and then break it. Then calculate the stitching required to reach the strength of the webbing and triple it. If this sounds like too much work, buy them.
* If you were making a tight rope 10 feet long and one 100 feet long, would you use the same cable? I doubt it, and you know why. So why assume the webbing is the same for all boats? the OSR says 4500 pounds, but if the boat is longer than ~ 35 feet and you use something stronger, with less stretch, the requirements go up. I once ripped a 4500-pound SS jackline off a boat with my hands; he forgot about the tight rope effect on forces.
Think about how much defection at the mid point you are willing to live with. But the less deflection, the greater the stress. I've used nylon rope, polyester webbing, and Dyneema rope covered with webbing. In each case the materials was chosen to fit the boat.
thinwater
Well-Known Member
How much side deflection do we think is acceptable? Consider a 400 pound load at the mid-point; the impact of a big man that was thrown downhill against something elastic.
With a 30-foot long jackline of polyester webbing, the tension on the jackline will be about 1000 pounds (4.6:1 safety factor--that is reasonable). The jackline will deflect about 3.5 feet from where it started, assuming it was in a straight line. In other words, it's going to be on about the center line.
If you use Dyneema, the deflection will be much less, but the force will be triple, nearly no safety factor.
Figure that into your tether length.
With a 30-foot long jackline of polyester webbing, the tension on the jackline will be about 1000 pounds (4.6:1 safety factor--that is reasonable). The jackline will deflect about 3.5 feet from where it started, assuming it was in a straight line. In other words, it's going to be on about the center line.
If you use Dyneema, the deflection will be much less, but the force will be triple, nearly no safety factor.
Figure that into your tether length.