How do I use a turnbuckle effectively?

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SUMMARY

The discussion centers on the effective use of stainless steel turnbuckles for sailboat rigging, specifically addressing issues of thread engagement and potential failure during use. The turnbuckles in question have a 1/4" cotter pin diameter and a thread length of 1 1/2", with a functional range of approximately 7 1/2". Users reported failures due to stripped threads after minimal use, suggesting that inadequate thread engagement and improper installation may have contributed to the failures. Recommendations include ensuring sufficient thread engagement, using quality hardware, and consulting with professional riggers for optimal performance.

PREREQUISITES
  • Understanding of turnbuckle mechanics and applications in sailing.
  • Knowledge of thread engagement principles and calculations.
  • Familiarity with marine-grade hardware specifications.
  • Experience with rigging adjustments and maintenance on sailboats.
NEXT STEPS
  • Research proper thread engagement lengths for various materials in rigging applications.
  • Learn about the differences between economy and high-quality turnbuckles for marine use.
  • Explore the use of jam nuts and lock wires in securing turnbuckles effectively.
  • Consult local rigging professionals for best practices in turnbuckle installation and maintenance.
USEFUL FOR

Sailboat owners, rigging professionals, and marine hardware enthusiasts looking to optimize rigging performance and prevent hardware failures.

  • #31
jack action said:
You have jam nuts. Use the jam nuts. More in the following video about jam nuts and lock wires:


As an obvious point for those that have not watched the video (time 2:40):
Jam nuts ADD to the strain on the threads, making them more likely to strip/fail.
Please keep it in mind!

Cheers,
Tom
 
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  • #32
OK, I tried google and failed; honestly, I tried. What is a SeaSaw? Bonus points for a picture.
I'd trade you for a picture of my last boat, a C&C 33, but you could just google that.
 
  • #34
Baluncore said:
or maximum adjustment range, turnbuckles are usually made with the two bolts,
That's not the only reason . Having a LH and RH thread means you don't need a swivel in the rigging; the only thing that rotates is the body of the turnbuckle.
 
  • #35
Tom.G said:
Jam nuts ADD to the strain on the threads,
My turnbuckles used a split pin through the tip of each bolt which wouldn't turn once it met the frame of the buckle (no stress on the bolt at that point). Not very strong and you could bend the pin but I never found one that undid itself.
 
  • #36
DaveE said:
OK, I tried google and failed; honestly, I tried. What is a SeaSaw? Bonus points for a picture.
I'd trade you for a picture of my last boat, a C&C 33, but you could just google that.
Aren't you sweet for asking!

MacGregor 26X powersailor with Honda BF50D.

1727922487197.jpeg

Top sailing speed: 7.0 knots (.6 knots over hull speed)
Top power speed: 14 knots

Baluncore said:
Teeter Totter ?
What do you think I named my dinghy launch? :wink:

sophiecentaur said:
My turnbuckles used a split pin through the tip of each bolt which wouldn't turn once it met the frame of the buckle (no stress on the bolt at that point). Not very strong and you could bend the pin but I never found one that undid itself.
Yes. These new $75 turnbuckles have that. My slipmate has a bigger boat with bigger TBs and I see he's taken out the split pins and inserted ring dings.
1727922918238.png

I think I will follow suit.
 
  • #37
Someone elseweb asked for a comparison of the $14 vs. $75 bolt threads:
1727922824224.png
 
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  • #38
DaveC426913 said:
What do you think I named my dinghy launch?
TT.
Like my 'Lady Mondegreen' and the tender 'Miss Heard'.
 
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  • #39
DaveC426913 said:
I think I will follow suit.
Very fiddly to use those rings and you really need strong fingernails. But they work well and don't do the damage that the sharp ends on split pins. Swings and roundabouts.
 
  • #40
Baluncore said:
TT.
Like my 'Lady Mondegreen' and the tender 'Miss Heard'.
That's clever!
 
  • #41
sophiecentaur said:
Very fiddly to use those rings and you really need strong fingernails.
Totally Agree. I hate em.
That they're all right-hand optimized makes it doubly frustrating.

sophiecentaur said:
But they work well and don't do the damage that the sharp ends on split pins. Swings and roundabouts.
Exactly.
 
  • #42
sophiecentaur said:
That's not the only reason . Having a LH and RH thread means you don't need a swivel in the rigging; the only thing that rotates is the body of the turnbuckle.
That assumes both bolts have the same pitch.

Less common LH threads are not required for a "body-only-turning" turnbuckle.

Differential pitch bolts of the same hand, can achieve the same adjustment range, with an optional advantage of length adjustment finer than the thread pitch employed.
https://en.wikipedia.org/wiki/Differential_screw
 
  • #43
Baluncore said:
That assumes both bolts have the same pitch.
Baluncore said:
Less common LH threads

These bolts wouldn't just be 'out of the drawer of random bolts'. Is it at all unlikely that they would not match, by chance. The two ends could be sourced differently so one just could be weaker than the other but the geometry would be the same for each.

And have you a marine example of a differential turnbuckle? :biggrin: I'd bet you could scour the catalogues for a long time before you found one.
 

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