Round brass thimble strength?

[benz]

Are the round brass thimbles sold by sailmaker's suppliers sufficiently strong to use in the eye of an HM running backstay? I know they're meant for rope and all, but HM rope is different than poly, and I wonder whether the pressure put on the sides by a tensioned HM line would be enough to crush the thimble or deform it. Anyone done tests?
Ben

[benz]

Really? nobody knows?

[Brion Toss]

Hi all,
I really thought the answer was obvious: no. Round thimbles are rarely seen outside of reinforced, load-sharing places, like sail clews. They are easy to tie to (think: sheets), and easy to fabricate around. But they are also easier to deform, as their constant radius leads to compression of the side walls in mid-ring. Compare this with a teardrop thimble, narrower for a given radius at the load, and the shape is kinder to the line attached, as the legs are pushed apart so. You'll find rings in heavy-duty situations, where there shape has some advantage, but they must have stoutness to compensate for geometry.
I use round thimbles for lifelines and lazyjacks, primarily. Might not hold up too well under heavy runner loads. Ring Hitch, anyone?
Fair leads,
Brion Toss

[benz]

Thanks. The obvious is not always clear to me; that's why I like this forum.
Ben

[Brion Toss]

Thanks for the kind words, but in reviewing my previous entry, I note the effects of writing it late at night, at the end of a long day. There was a time when round thimbles were the only type available, even for heavy loads; the ones in sails are a surviving example, in a special context, as are other surviving round thimble or ring applications. And of course no thimble -- and no block-and-tackle -- is the best way to do runners, I think. Just one block on deck, with a good lead to take a continuous, single-part HM runner to the empty weather primary winch. Much more power, instant overhaul and take-up, no blocks banging you in the head, neat cheaper. And no thimbles of any shape needed.
Fair leads,
Brion Toss

[benz]

I am considering runners such as you describe, but have to work out a few issues of proper lead. And I'd have to buy another winch handle--something I've not missed since it went by the board a year ago or so. Do you fear possibly over-tightening the runner with a winch?
Ben