When to stick a thimble in the eye?

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When to stick a thimble in the eye?

Postby KenKorey » Mon Jul 23, 2018 11:22 pm

I've never been entirely certain what principles to apply for adding a thimble when setting up an eye for attaching a rope to a shackle or other fitting. I've usually replicated the setup that the PO used without ever being clear what dictated the choices. Since fittings like bails and shackles can be made either of metal stampings (with more-or-less rectangular cross-sections) or of forgings and castings with relatively rounded cross-sections, I would have guessed that a flat strap is much more likely to chafe the eye of the rope than would a rounded alternative, leading to use of thimbles where flat straps are involved and less often where they are not. On my boat, however, this principle seems to have been largely irrelevant to the actual rigging practice. I suppose that different owners made alterations to the rigging each by their own lights and that I shouldn't expect much consistency, but I'm currently renewing the aging rigging and I'd like to get it right from the start. Can anyone refer me to a more definitive principle for using thimbles than doing what the last guy did?

Thanks,
Ken
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Re: When to stick a thimble in the eye?

Postby GreenLake » Tue Jul 24, 2018 12:13 am

For wires you need thimbles; for rope, latest I read is that thimbles aren't universally advised. (If you attach to something really rough, you will need chafe protection, of course).

On my boat, I used to have thimbles for main and jib halyard. The jib halyard was redone in Amsteel and at that point I incorporated an soft-shackle into the end. Instructions for that can be found at http://l-36.com. The jib now has a short bit of line with a diamond knot at the top, like a toggle.

For the main, I still have a thimble, but I don't use it, or the metal shackle it was used with. I now make a luggage-tag hitch at the head of the sail (and the thimble makes sure it can't slip). That setup has given me an extra inch or so in hoist and has worked fine for several seasons. Novice crew are always puzzled how to tie a luggage hitch with access to only one end of the line and the thimble wider than the grommet at the head. (It's not that hard :D)

For the vang, I think I just used knots to tie on the becket. I use buntline hitches, which are very compact.

For jib sheet I don't use any knots or thimbles. I have a continuous jib sheet, with a soft shackle as a Prusik loop. The continuous sheet does great in avoiding snags and the soft shackle gives a bit of lightweight line between sheet and clew - that seems to have the effect of reducing how much the jib sheet gets jerked around from headsail flogging during a tack.

That basically covers any place I would expect to ever see thimbles, except, as mentioned, for wire stays etc. if they are done that way as opposed to some other type of connection.
~ green ~ lake ~ ~
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Re: When to stick a thimble in the eye?

Postby KenKorey » Thu Jul 26, 2018 7:00 pm

Thanks GreenLake -- your explanation is quite helpful. It's made me realize that I have too many thimbles on my boat, which I'm happy not to have to replace. I suspect that one of the earlier owners was caught up in splicing eyes wherever possible, and popped a thimble in each. I'm just as happy with substituting hitches wherever I can and am inclined not to splice eyes without clear reason. Avoidance of chafing is the primary purpose of thimble use -- exactly why I've used them to affix anchor rodes to their galvanized chains -- but I plan to avoid their promiscuous use henceforth.

Regards,
Ken
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Re: When to stick a thimble in the eye?

Postby GreenLake » Fri Jul 27, 2018 3:13 am

Splicing can be fun. Try making your own soft shackles (instructions at https://l-36.com and other places). Amsteel is easy to splice, although the methods at first look unconventional when compared to traditional splicing methods for three-strand or double-braided rope.
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