Strapping material for clew block

[Bash]

Yesterday, close-hauled in 17 knots of breeze, I blew the clew off a six-year-old dacron OEM mainsail. Although I had the outhaul tight to flatten the sail, it surprised me to have the dacron straps fail on a sail that is still holding its shape well.

I'm hoping to keep the sail for at least another four years before it becomes my backup sail.

The particular clew block I'm using has three slots for 1" straps. I'm wondering whether it would be better to specify a different material, such as kevlar, for the replacement straps.

Any advice appreciated.

[Vasco]

Was it the stitching? The clew is always in the sun.

[thinwater]

Originally Posted by Bash

Yesterday, close-hauled in 17 knots of breeze, I blew the clew off a six-year-old dacron OEM mainsail. Although I had the outhaul tight to flatten the sail, it surprised me to have the dacron straps fail on a sail that is still holding its shape well.

I'm hoping to keep the sail for at least another four years before it becomes my backup sail.

The particular clew block I'm using has three slots for 1" straps. I'm wondering whether it would be better to specify a different material, such as kevlar, for the replacement straps.

Any advice appreciated.

Without pictures, it's hard to picture what tore. I'm assuming it was the webbing.

Really, there isn't much point in having the webbing too much stronger than the sailcloth. That said, the webbing can be long to spread the load. The webbing should be non-stretch (most are).

I think what probably got you was UV. Does the sail cover reach over the end, or does the clew board stick out just a bit? If so, that is the cause and covering the end is the cure.

Chafe is another possiblity. The board may have a sharp edge. Round it and perhaps add a guard.

I'm rather surprised the damage was not visible before it blew. Or perhaps it was, and most of us don't llok too closely.

[estarzinger]

Originally Posted by Bash

The particular clew block I'm using has three slots for 1" straps. I'm wondering whether it would be better to specify a different material, such as kevlar, for the replacement straps.

best is spectra/dyneema webbing with PTFE thread (look up Tenara Lifetime Thread). Of course it costs more (an understatement).

The PTFE thread is slippery and it often takes the sewing machine operator some time to set the machine up (thread tension) to make good stitches. Even with spectra webbing a lot of lofts still use polyester thread, usually V92, (because they don't want to have to fiddle with the machine thread tension), just more of it.

[sy_gilana]

We use Tenara by Gore. Its very expensive but will outlast the material beneath. Usually tension is stepped up about 4 clicks more than normal. One drawback, it is slippery, and if the thread is cut, the whole shebang could run out. Its important to back stitch every few feet. For webbing its the right choice.

[Bash]

Originally Posted by Vasco

Was it the stitching? The clew is always in the sun.

No, the stitching is fine. The strapping itself broke. All three straps gave up catastrophically. One moment I was close-hauled and loving life, the next moment the clew block separated from the sail, and it was flogging wildly.

This was a UK OEM sail, and the strapping was exposed, sewn outside the Sunbrella UV cover. I've already asked my sailmaker to sew the replacement directly to the sail and then cover it with white Sunbrella.

The question is whether I should ask for something other than dacron replacements for new strapping.

[thinwater]

Six years in the sun is a lot. If you cover it, given the sail is 6 years old, I'm certain polyester will do fine.

Odd, that the most highly stressed part of the sail is often poking out like that. But a very common failure for that reason.

I doubt going to spectra would change the price by more than $10. Or at least the material cost won't! Not Kevlar; it won't like the short radius and thus wouldn't do any better than polyester.

[estarzinger]

Originally Posted by Bash

The question is whether I should ask for something other than dacron replacements for new strapping.

Well I can give you two opposite logical answers:

Your old Polyester straps lasted 6 years, and you only expect to run the sail for another 4 years. So, the Polyester straps should be fine.

Or

You had an important bit break and you will want to improve it/make it stronger when you fix it, and the improvement here is clear (spectra webbing) and not difficult, nor all that expensive.

I personally would go with option #2.

[Blue Stocking]

No UV protection on the Clew ring, eh--unusual!!. My Doyle Quicksilver has leather protection, which extends far enough into the sail, and keeps straps behind Sunbrella.
Note: not a Doyle rep.

[Bash]

Originally Posted by Blue Stocking

No UV protection on the Clew ring, eh--unusual!!. My Doyle Quicksilver has leather protection, which extends far enough into the sail, and keeps straps behind Sunbrella.
Note: not a Doyle rep.

It's not a clew ring, which would normally be in a leather sleeve. Rather, it's a clew block. A SeaSure block, as pictured below. I don't believe I've ever seen a UV cover for the block itself.

[Bash]

Originally Posted by estarzinger

Well I can give you two opposite logical answers:

Your old Polyester straps lasted 6 years, and you only expect to run the sail for another 4 years. So, the Polyester straps should be fine.

Or

You had an important bit break and you will want to improve it/make it stronger when you fix it, and the improvement here is clear (spectra webbing) and not difficult, nor all that expensive.

I personally would go with option #2.

That's exactly what I'm thinking, especially with a loose-footed main. If someone had been going forward on the low side at precisely the wrong moment, the force of the sail could have swept that person overboard.

And even if I replace the main four years from now, it still becomes the back-up main, which means I still want it to be reliable if it's ever pressed into service.

[Jim Cate]

So, Bash, why can't you (or your sailmaker) stitch some Sunbrella around or over the webbing? Seems as if that would solve the UV issue. But, using the Spectra webbing isn't a bad thing either!

Cheers,

Jim

[thinwater]

Originally Posted by Bash

It's not a clew ring, which would normally be in a leather sleeve. Rather, it's a clew block. A SeaSure block, as pictured below. I don't believe I've ever seen a UV cover for the block itself.

When I suggested "cover it" I meant with the sail cover when not in use. If it is something goofy like in-mast furling, that does not mean a cover could not be fabricated.

If it had been covered, the service life might well have been 20+ years of weekend use. It really is the UV. The insidious thing about UV damage is that whatever the material, though it is not hard to see it is very difficult to judge the seriousness. Spectra is about as vulnerable as polyester, but you will be starting with more strength.

___________

And there will never be a substitute for regular of key bits. I've had all sorts of things blog like that on a breezy day. Shackles, pendants, sheets, cars....

[Blue Stocking]

Originally Posted by Bash

It's not a clew ring, which would normally be in a leather sleeve. Rather, it's a clew block. A SeaSure block, as pictured below. I don't believe I've ever seen a UV cover for the block itself.

I stand corrected, fingers ahead of brain. I now see that you referring to a mainsail, not a jib. Sorry!!

[Bash]

Originally Posted by Jim Cate

So, Bash, why can't you (or your sailmaker) stitch some Sunbrella around or over the webbing? Seems as if that would solve the UV issue. But, using the Spectra webbing isn't a bad thing either!

A good question. Although the part of the strapping that touches the sail will all be covered with Sunbrella, I've never seen someone cover the attachment points.

Has anyone done this? If so, I'd love to show the pics to my sailmaker. Even if it looks goofy, I can't see much point to covering 99% of the strap if the 1% that get's the most chafing is exposed to sunlight.

(BTW: I've already decided to go with something other than dacron.)