FID length, core bury, cover bury

[Brion]

Hi all,
I've just left a strongly-worded note over on the Tuttle thread. You might find it useful for this one. Meanwhile the short form is that proper bury lengths preclude any likelihood of splice failure; you can get away with less, most of the time, but why take that chance?
As was pointed out above, I use 24 diameters as a basis, because it is easier to calculate tail lengths. But I begin the taper earlier, and allow for 8 diameters takeup, so that things aren't any tighter than with the 21-diameter taper. This is significant because stuffing too much rope inside makes the splice weaker, as well as making it harder to run home.
As for different manufacturer's recommendations, I might be reading things wrong, but I think that New England, Yale, and Samson all use the classic long-fid/short-fid combination, varying bury based on specific splices and constructions. The techs at all of these companies are deeply conservative, but not absurd about it.
Fair leads,
Brion Toss

 

[Marden]

Brian,

I am not currently a rope industry professional, so this is more of a personal mission for me. Do you know of any studies out there which determined correct fid size, or is much of this information based mainly on individual pull tests ? Please correct me if there is more data, but it is concerning more scientific research does not seem to be available.

If this is the case, perhaps a committee based on experts like you and the major rope manufacturers should work to establish better defined, more consistent standards for splicing techniques.

Considering so many lives of rope industry professionals depend on these splices on a daily basis, it seems important to have detailed tests based on numerical analysis with a comparison of different fid configurations (ie 21, 22, 24 rope diameters). The results should conclude what length should be used.

Respectfully,
-Michael

 

[Brion]

For data on all things rope, I can recommend the literature available from the Cordage Institute. But I've often found that talking with the techs at good companies gives results at least as good. They really care about this stuff, and they have data as deep as you could wish for.

 

[Marden]

Brian,

This site has some very interesting information. Also, it's great to see a standards committee, so thanks for posting this site info.

Unfortunately, after looking through the site it does not answer my original questions what the best measurements to use for:

1- FID size = (21, 22, 24, or another number) x D
2- length of core bury
3- length of cover bury

I just wish there is a more definitive compilation of data that shows this.

Oh well. Using 24xD does make the math easier.

Thanks again Brian !
-Michael

 

[NickfromWI]

Brion- if we do a side by side comparison of the Yale, Samson and NER directions, there are some differences in the measurement. Some call for a short fid of something where others ask for a half fid. But the differences are subtle and I doubt consequential.

 

[NickfromWI]

[ QUOTE ]

Unfortunately, after looking through the site it does not answer my original questions what the best measurements to use for:

1- FID size = (21, 22, 24, or another number) x D
2- length of core bury
3- length of cover bury


[/ QUOTE ]

21 or 24? It doesn't matter.

Everything else, just stick to the manufacturers directions or something else that makes sense.

I think that if we had ten of us splice 30 ropes, ten each using various fid lengths, I'm sure we'd find that the differences were negligible.

 

[oceans]

[ QUOTE ]
[ QUOTE ]

Unfortunately, after looking through the site it does not answer my original questions what the best measurements to use for:

1- FID size = (21, 22, 24, or another number) x D
2- length of core bury
3- length of cover bury


[/ QUOTE ]

21 or 24? It doesn't matter.

Everything else, just stick to the manufacturers directions or something else that makes sense.

I think that if we had ten of us splice 30 ropes, ten each using various fid lengths, I'm sure we'd find that the differences were negligible.

[/ QUOTE ]

x2!

 

[Marden]

These splices are so strong that I agree that it probably does not matter.

Thanks for all your feedback !!!

-Michael