Dyneema DUX long bury vs brummel splice

[pwillems]

I have just collected the DUX for the rigging replacement on my 65ft schooner. I am replacing all of the rigging with mostly 13mm DUX and will be parcelling and serving it old school style for UV and chafe protection. In my mind, this should give it a mostly infinite lifespan.

I am trying to find some data on strength of a long bury splice (80d) against a brummel splice. I feel like with the serving keeping the splice compressed even at rest, I will not need the lock from the brummel and I will gain a strength advantage by not upsetting the braid in the way required for the brummel. Another small perk will also be the visually more pleasing result without the bulge created at the splice site using the brummel method.

Does anyone know of any information sources that can clarify this?

[Breaking Waves]

Originally Posted by pwillems

I have just collected the DUX for the rigging replacement on my 65ft schooner. I am replacing all of the rigging with mostly 13mm DUX and will be parcelling and serving it old school style for UV and chafe protection. In my mind, this should give it a mostly infinite lifespan.

I am trying to find some data on strength of a long bury splice (80d) against a brummel splice. I feel like with the serving keeping the splice compressed even at rest, I will not need the lock from the brummel and I will gain a strength advantage by not upsetting the braid in the way required for the brummel. Another small perk will also be the visually more pleasing result without the bulge created at the splice site using the brummel method.

Does anyone know of any information sources that can clarify this?

Sure, I, and a number of others have destruction tested this.

For strength: You are correct that the Brummel creates a strength loss (somewhere on the order of 5-10%). A long bury with lock stitching is viewed as generally best practice when strength is a significant concern. However, if you are correctly sizing the Dyneema stays (for creep), then they will be oversized for strength, and thus a small strength loss in the Brummel is moot.

Asides:

Bury length - There is no real point in doing an 80d bury. There is no testable advantage to do that - really not gain above around 45x. But there is also no downside (otther than cost/time) and if you just want to, np.

Low load slipping - As I mention above, lock stitching the bury is the accepted and proven best practice here. If I were you I would do that - done properly it is full strength - just be sure to read and follow some good instructions on how because by doing it wrong you can create a strength loss similar to the brummel loss.

I have not (and I don't know anyone who has) specifically tested full parcelling and serving as a way to 'lock' a bury and prevent low load slipping. I do know that this has been tested as a potential way to create an end loop (as a potential alternative to a splce), essentially trying to clamp the tail and standing part together, and it was unsatisfactory. Unlike wire, the textile does shrink its diameter when put under working load, and that reduced the clamping force of the parcelling and serving. It might well work to prevent slipping in the bury because the diameter shrinking only occurs under load when the Chinese finger effect already stops slipping - but it is an untested application - I would put some stitching under it to be sure.

UV damage - UV has a tested/proven ability to penetrate about 4mm thru tight weave dacron braided covers. So, I would not assume your parcelling and serving would give you 'infinite UV protection. The best UV protection is provided by solid rubber/'plastic' dipping or tubing - that is how all the best textile yachting stays are protected.

[tamicatana]

Brion Toss recommended a 72-diameter, tapered, bury for HMPE line, at least in the book I have.

As for UV, coating with something seems to be working for me. I’ve been using textile rigging for well nigh 20 years on multiple boats for things from standing rigging to lifelines to trampoline and its lacing. I’ve used Yale’s Maxijacket, but here lately I’m experimenting with plain old good quality latex paint (Clark & Kensington exterior) and so far 9 months sub-30 lat it’s going well

[Benz]

A brummel will let you get away with a shorter bury. I routinely bury 14 inches with a Brummel in that diameter DUX. I also have access to a hydraulic ram to pull it to 30% of break load and get it good and settled in before sending it out into the world.
If I were in your shoes, I'd do a 45x diameter straight bury (no brummel), begin my taper halfway along the bury, and lockstitch very carefully AFTER putting as much load on the line as possible, not going beyond 30% of BL.
If you're going to cover it, it's worthwhile learning to do a covered core-to-core splice, slide some dyneema jacket over the DUX, and splice it that way: then your entire length of DUX can be covered. Paint it with Maxijacket or Armourcoat, and refresh the paint every couple years. Should last a good long time.