How to lash a ring to a spar

[whimsy]

I'm junk rigging Flutterby right now, and having trouble with my yards.

I need to attach two blocks to each yard, one for the halyard (3:1 purchase), going UP, and one for the yard hauling parrel (simple block, pulling at 90 degrees to the halyard. In normal use, the yard itself is at 50 or 60 degrees from horizontal. The "conventional" solutions involve hardware bolted to a (wooden) yard. I don't want to drill holes, or weld anything if I can do what I want securely using rope.

My yard is an aluminum pole (2.3 inch outside diameter) I've got a 2 inch diameter SS ring. I'm thinking to try lashing it to the yard so that the open axis is perpendicular to the axis of the spar like this:

______O______
----------------------

I would then use normal SS shackles to attach both blocks to the ring.

Now I'm trying to decide how to tie it on. A round lashing looks like a possibility. A shear lashing (with frapping turns) looks better.

My halyard is 3/8" polyester braid. Since it is a 3:1 purchase, to approximately match the strength I would want at least three turns of this size rope. Four turns through the ring is the absolute maximum before it rides too far up the sides. If I wanted more turns (looks normal for this sort of lashing), I'd have to go to something smaller. I've got 1/4" polyester line and 1/8" cord I could use instead.

Does the lashing sound secure? Would something else work better?

[benz]

Use the 1/8" twine. Many of my fittings are lashed on with it, and they hold just fine. A thick line, is, after all, made of many thinner ones.

[Brion Toss]

Hello,
Consider eliminating the ring and the shackle; nowadays we are seeing the re-emergence of stropped blocks, fabulously strong and light. And not necessarily spendy. Lashing with nylon or spectra, you can get a better result, with clean looks to boot.
As for lashing options, you might want to confer with Mr. Ashley.
Fair leads,
Brion Toss

[whimsy]

As I was researching this on the web, I realized how much I really ENJOY knots, splices, lashing, etc. Mr. Ashley is now on my Christmas list

I have two reasons not to lash the blocks directly to my yard:

1. I'm a cheap, and I already own blocks that can't be lashed on directly.
2. With a shackle, it is much easier to remove the block from the yard and attach it to a bosun's chair or harness and go up the mast myself.

I did something that I think will hold using 1/4" polyester. Pretty much the shear lashing I proposed, with an extra hitch on one side and the tails knotted together use up the remaining rope and provide a little "insurance". I worked the turns tight levering with a rounded screwdriver. (Picture below; sorry if it is inconveniently big.)


Does it look like this will hold my sail up reliably?

Brion, is there a reason you suggest lashing with spectra or nylon? I notice that what I used (polyester) is off of the list? I believe that all three are fairly resistant to chafe and UV. I've never thought about how desirable stretch is in a lashing, and all three are very different there.

[benz]

It will hold, as long as the knots are tight enough to not shake out. I like thinner line because the frapping would lie more tidy, and nylon is nice because if pulled pretty tight the stretch will help hold the knots in. If using Spectra or Dyneema lashing, you'd want an even thinner diameter than nylon, and to back up the knots, as it's slippery enough stuff to easily shake them out. Ashley will be a very good resource for lashings.

[Brion Toss]

Hi again,
As we move back into the art of lashing, it is perhaps inevitable that we will repeat some of the details of its evolution. The materials are what is new -- that Dacron is at least twice as strong as natural fiber, and requires a much lower safety factor -- but the logic is the same. Therefore, consider leaving a "neck" to frap, simultaneously allowing for tighter turns and ring articulation. Consider frapping with a separate seizing, for tidier, sounder lashing turns. Consider screwing, riveting, or even lashing thumb cleats on.
What you have now appears to put needlessly high loads on the turns that go through the ring, to be vulnerable to the failure of any part of the lashing, and to have little ability to articulate. It's a start, and a noble one, but it could be elegant.
As for materials,tarred nylon twine is readily available, and tough. Spectra just multiplies strength completely beyond belief, and can give you lashings that are basically immortal. Multiple turns of small stuff is always stronger than one turn of large, volume for volume. This is why selvagees are stronger than the rope they are made from.
Fair leads,
Brion Toss