Snowgoose-1
Well-Known Member
Just for info, do you sew by hand, and how many rows of stitches.
Ta
UV damage and webbing jackstays
- Thread starter NPMR
- Start date
Ta
Neeves
Well-Known Member
Dyneema has no elasticity, the shock loads could be enormous damaging the jack stays, specifically the stitching, the individual and the points of securement of the jackstays. You could use nylon tethers - but they are so short as to have minimal stretch.
Jonathan
zoidberg
Well-Known Member
Snowgoose-1
Well-Known Member
Well found.
The breakage seems to be where the webbing is attached to the trailer . Difficult to tell if the stitching was the weak point when it is held up by the Shrimper owner.
Even if you have numerous rows of thread , the thread will still not save the day if it is susceptible to UV damage.
What if you used a stainless buckle then stitching for extra security ?
thinwater
Well-Known Member
A. Does anyone have documented (link) or personal experience of jackstays failing? I only know of two and I am collecting data. It is very rare. I am NOT discounting or judging risk, ONLY collecting data.
B. DIY stitching is touchy subject unless you can pull test your work. There are articles you can Goggle. It is not as simple as how many rows or what thread, because the material you are stiching is also a very large factor. Too much to cover in a post. That said, there are reasons, beyond economy, for why webbing is bar tacked; it gives a stronger, more repeatable result.
C. Dyneema single braid is an option. As Neeves pointed out, the impact forces are greater, so make DARN sure the anchors are as strong as the line. Also, you probably want to go up one size from World Sailing requirements to 6 mm. Part of this is increased strength to handle impact loads, and part is for durability (more allowance for UV damamge). I wrote this up for PS (including testing of geometry and the rolling under foot of various options) but it has not been published. Curiously, Dyneema covered in webbing did poorly. Fat and slippery.
D. The jackstays should be easy to differentiate from other rigging. You don't want to clip a halyard running along the deck by mistake. Something about them should be very different.
---
The important things are:
B. DIY stitching is touchy subject unless you can pull test your work. There are articles you can Goggle. It is not as simple as how many rows or what thread, because the material you are stiching is also a very large factor. Too much to cover in a post. That said, there are reasons, beyond economy, for why webbing is bar tacked; it gives a stronger, more repeatable result.
C. Dyneema single braid is an option. As Neeves pointed out, the impact forces are greater, so make DARN sure the anchors are as strong as the line. Also, you probably want to go up one size from World Sailing requirements to 6 mm. Part of this is increased strength to handle impact loads, and part is for durability (more allowance for UV damamge). I wrote this up for PS (including testing of geometry and the rolling under foot of various options) but it has not been published. Curiously, Dyneema covered in webbing did poorly. Fat and slippery.
D. The jackstays should be easy to differentiate from other rigging. You don't want to clip a halyard running along the deck by mistake. Something about them should be very different.
---
The important things are:
- Location. The lines should end ~ 4-5 feet from the bow and stern. Locate them inboard if practical, but mostly, hold on when moving.
- Slack. Minimize.
- Clip hard points. Nearly all MOBs are when the person is NOT moving, but is working on something and not paying attention to the motion of the boat. Clip short before working, particularly at the bow and mast. In fact, this is probably more important than using jackstays. People seldom fall when moving, holding on, and paying attention. It's when their focus is somewhere else.
Roberto
Well-Known Member
I use webbing with 1.5x 2x the (usually suggested) 2t breaking load, whatever I find, and sew them with the Sailrite. Loose a bit of maximum load here and there, there will still be a comfortable safety margin. A bit like soft shackles, if in doubt go oversize, after all it's for personal use and not to be sold, no Breaking Load guarantee or whatever.
Type of stitches, I use both the 7 rows and the "W" patterns indicated/tested here (note the "boxed-X" does not seem particularly good)
dansaskip
Well-Known Member
Ah but you wouldn't use stitching - that is why I specified using a splice. The strength of the right size of dyeema is 4,800kg for 5mm - I would use 6mm instead as against strength of 2,100 kg for webbing . So there is a much greater safety margin and less likely hood of shock force damage .There again webbing is not very elastic and there are different varieties of webbing some of which are not suitable for jackstays -really only high tenacity polyester is suitable.
14K478
Well-Known Member
On looking at my polyester webbing jackstays I noticed that they have gone furry on the side in contact with the deck.
Otherwise they seem fine.
Otherwise they seem fine.
Stemar
Well-Known Member
The best jackstays I've ever seen are those on our Catalac. The grab handle runs the full length of the cabin top and is a bronze c section with a slider in it to clip onto.
She'll most probably be our last boat but, if not, I'd definitely look at the possibility of fitting something similar to a new one.
She'll most probably be our last boat but, if not, I'd definitely look at the possibility of fitting something similar to a new one.
Chiara’s slave
Well-Known Member
I’m about to fit our 3rd set since we had the boat. UV is pretty bad for them, 2 years sounds reasonable to me. They make trailer tie down in their later years.
14K478
Well-Known Member
I am admiring your boom strap because I know I ought to replace mine… I do have a Sailrite and I ought to be able to do that…I use webbing with 1.5x 2x the (usually suggested) 2t breaking load, whatever I find, and sew them with the Sailrite. Loose a bit of maximum load here and there, there will still be a comfortable safety margin. A bit like soft shackles, if in doubt go oversize, after all it's for personal use and not to be sold, no Breaking Load guarantee or whatever.
Type of stitches, I use both the 7 rows and the "W" patterns indicated/tested here (note the "boxed-X" does not seem particularly good)
Webbing can easily be sewn even with a domestic machine, just go slowly, as an example I made this boom strap with a domestic machine, it's about 1cm thick I might possibly lift the boat with it.
View attachment 185298
Roberto
Well-Known Member
Thanks
Just remember if you sew several layers keeping it flat then it won't take the U-shape, sew it while keeping it curved, adding maybe a few staples here and there to keep all layers together in the final shape.
thinwater
Well-Known Member
Something he did not explain, because I think he may not have noticed, is that the best pattern depends on both the construction of the webbing and how much it stretches. The patterns for nylon, for example, are different from polyester. This is what happened at 5:50, and he didn't know why. The reason is that the webbing was stretching, loading some rows more than others. The lower the stretch, the less the pattern matters.
The real rule, based on the stitch testing I have done, is that you need to do some samples and test them with winches.
testing webbing
Chiara’s slave
Well-Known Member
This thread has made me re think. Why not 8mm dyneema, with splices not sewn loops?
thinwater
Well-Known Member
Rope tends to roll under foot. Dyneema can be used, but it needs to be thinner, like 5 or 6 mm. I tested this for PS.
There's a lot more to not falling off than jacklines. The main thing with jacklines, IMO:
- Run them as far inboard as practical.
- Clip short.
- Don't stand when you should scoot.
- stop them ~ 5 feet short of the bow and stern.
- Practice with them in nice weather, fixing everything that is not trouble-free. You don't want to be sorting then out, and your understanding of how to work with them, in a storm. They should be second nature.
- Plan your movements. This is the first line of defense.
Not Falling Off: A Guide - Practical Sailor
Chiara’s slave
Well-Known Member
On a tri, none of those things are a problem, neither is standing on the jackstay. You just don’t walk on that part, it’s 7ft from the edge of the boat, 7ft short of the bow and 5ft short of the stern. At sea, you’d normally crouch or crawl on the tramps unless going hand over hand on the coachroof. Then you’d walk upright on the tramp, the handholds are at hand height as you sink in to the tramp a bit. 6mm is obviously cheaper and lighter, so why not.
PabloPicasso
Well-Known Member
I have seen jackstays with stainless fitting at either end. So they fold back and go through a buckle. Rather like straps on a back pack or LJ
So not relaint on stiching, and fully adjustable.to.boat length.
So not relaint on stiching, and fully adjustable.to.boat length.
chriss999
Well-Known Member
It’s easy to make a cover to slip over the stitched ends to protect the stitches from UV.
Babylon
Well-Known Member
The s/s fitting is an Ankarolina buckle which I've always had on my boat at the cockpit end, with a stitched loop for a shackle at the bow end. Advantage is that webbing is fully adjustable (one wants it fairly taught of course), disadvantage is that the stitched loop for the shackle forward is the theoretical weak point (through abrasion and/or UV deterioration). So I was thinking of getting a second pair of buckles to eliminate stitching altogether, but the webbing needs some slack to open the buckles slightly to get them onto (and later off) the U-bolts, so one at each end would result in a slack line which isn't good.
My pair of very heavy-duty white webbing jackstays (with a massive excess of machine stitching at the loop ends) are now pretty old, circa 15yrs! Even though I've always removed them and stowed them in the dark below when not in use, it seems prudent to replace them.
Jimmy Green do made-to-measure webbing jackstays (I don't think as thick as my existing old webbing). Their coloured webbing is rated to 2000kg as the colouring process heats and therefore weakens the material, whereas white is rated to 3000kg.
Chiara’s slave
Well-Known Member
2000kg is a 20g pull for the average wet guy on a lanyard. That’s going to sting a bit, as they say. Unless you’re exceptionally fat, I think 2000 kg is probably enough.
