Dyneema splices - length of bury

[zoidberg]

Several US/Youtube videos on splicing Dyneema/Amsteel/Whatever single-braid lines state a requirement for '72 x diameter' for the length of bury.
Marlow's Rob Henderson insists that '50 x diameter' is sufficient.

Que pasa...?

 

[nigel1]

I think it is 72 x d if no brummel lock is used.

 

[thinwater]

Brummel has nothing to do with it. Stitching lock can be just as strong. If a brummel was better, would they not recommend that for towing ropes? In fact, it is slightly weaker. The Brummel is just neat and easy. In truth, if you just pinch the rope with your finger when the load comes on it works.

Whoopie slings are a good example. No lock. The lack of taper at the exit does make them about 15% weaker.
Samson whoopie slings
Animated Knots

Testing generally shows no improvement in strength past 50x, and generally very little improvement past 35x, but 72x is a very conservative figure. It's just a difference of opinions on safety factors.

 

[Neeves]

Individuals using/making you tube take no responsibility for their recommendations, Marlow et al have a reputation to defend. The difference in cost, to you, or the inconvenience in working with 75 is....nothing.

To me its a no brainer. Go, roughly, with 75 and sew - and I then use a shrink cover for many such splices, mainly because the splice is worked, handled, a lot and the cover makes the splice 'less floppy' - depends on application.

Jonathan

 

[thinwater]

^^ The only reason for less are constructions where space is limited. For example, in cascade purchases with LFRs you may not want the stiffness of the splice running over the ring. Reducing the bury a bit (not rediculously short, but I'm not giving a figure) can solve the problem. But this isn't standing rigging, as a rule. Also, many Dyneema applications are so far below the WLL that the risk of a slight reduction just isn't important. But that determination is on you, and as Neeves said, Samson won't say it.