HR shackles can explode

[s/v Jedi]

Y’all are overlooking this: the OP has a high performance cat, not a monohull. For monohull, rig sizing can be reliably calculated because of the shock absorbing effect of heel. A catamaran has such a high righting moment that the shockloading is much higher and rigging is specified according to tests and experience.

In this case, experience shows that the hardware choice needs to be adjusted. Not just for OP’s boat but for all of them with that particular choice of hardware. Instead of just going bigger, I recommend looking at re-engineering choices like soft shackle vs steel shackle. There are very good blocks that attach with Dyneema in this application. The properties of Dyneema seem favorable for preventing the described failures

[Dockhead]

Originally Posted by s/v Jedi

Y’all are overlooking this: the OP has a high performance cat, not a monohull. For monohull, rig sizing can be reliably calculated because of the shock absorbing effect of heel. A catamaran has such a high righting moment that the shockloading is much higher and rigging is specified according to tests and experience.

In this case, experience shows that the hardware choice needs to be adjusted. Not just for OP’s boat but for all of them with that particular choice of hardware. Instead of just going bigger, I recommend looking at re-engineering choices like soft shackle vs steel shackle. There are very good blocks that attach with Dyneema in this application. The properties of Dyneema seem favorable for preventing the described failures

Yeah, I mentioned that upthread. I completely agree with you.

[fxykty]

Originally Posted by s/v Jedi

Y’all are overlooking this: the OP has a high performance cat, not a monohull. For monohull, rig sizing can be reliably calculated because of the shock absorbing effect of heel. A catamaran has such a high righting moment that the shockloading is much higher and rigging is specified according to tests and experience.



In this case, experience shows that the hardware choice needs to be adjusted. Not just for OP’s boat but for all of them with that particular choice of hardware. Instead of just going bigger, I recommend looking at re-engineering choices like soft shackle vs steel shackle. There are very good blocks that attach with Dyneema in this application. The properties of Dyneema seem favorable for preventing the described failures

Not all connection types are suitable for soft shackles or lashings due to hard edges or other chafe causes. Only use soft if you have a rounded edge.

Whatever you’re attaching the UHMWPE soft shackle or eye or lashing to should be at very least the same radius or larger than the diameter of the line you’re using e.g. 8mm pin diameter should have 8mm or smaller diameter soft shackle/line. Larger diameter line is OK if strength is way over what is required.

[s/v Jedi]

Originally Posted by fxykty

Not all connection types are suitable for soft shackles or lashings due to hard edges or other chafe causes. Only use soft if you have a rounded edge.

Whatever you’re attaching the UHMWPE soft shackle or eye or lashing to should be at very least the same radius or larger than the diameter of the line you’re using e.g. 8mm pin diameter should have 8mm or smaller diameter soft shackle/line. Larger diameter line is OK if strength is way over what is required.

Yes, that is why I wrote that you need to buy the hardware that is designed for the application. In this case you can buy a block that can be spliced directly to the Dyneema runner, or if the runner splice somehow can not be taken out, use a softshackle or loop, depending on the brand and style of block.

[s/v Jedi]

Here’s an example of runner with loop block

[Cheechako]

-I think they are marginally sized regardless of what the factory says. Their job is cost.
-I would want the narrowest shackle that would work rather than those wide ones.
- Aircraft designers tend toward 3x the calculated minimum for safety.
-17-4 ph is way way stronger than 316, and much stronger than most Titanium also.

-Wichard has the best shackles IMHO.

[fxykty]

Originally Posted by s/v Jedi

Here’s an example of runner with loop block

Currently our runner is wire, so it terminates to a toggle. Easy to connect with soft shackle, loop or lashings to the toggle. When we re-rig next year we’ll replace the wire stay with UHMWPE, as you’ve got in the photo. Why not just make the eye longer and splice it through the mouth of the block and do away with the loop? I like the idea of eliminating connecting parts if possible.

What is the make of that block? The Harken loop blocks I’ve used require a soft becket lead all the way back to the anchor as you can’t lead the becket loop through the mouth and pull up.



Note that this was a preloading tensioning to equalise the lashings and the secondary lashings are not yet tightened nor tied off with Carrick Bends as recommended. I’m also upgrading the 75s to 100s to better match the breaking strength of the backstay and its fittings (approximately 6200kg)

[s/v Jedi]

I really like Antal and dream I have Karver

[Dsanduril]

Fxykty, been following as we have the same rig, and probably the same shackles - or at least very similar.

One thing I prefer about the soft shackled setup as Jedi pictured is that the loop goes through the block’s axle. If you get a failure of the block material you only get 10cm or so of elongation before the loops catch, possibly saving the rig. With beckets/shackles once they blow up the stay is loose.

Anyway, thanks for posting, it will have me making sure my regular inspections are a bit more detailed.

[AKA-None]

2kg hmmm I can pay for that by drinking less and lose the weight by reducing my weight. Ymmv

[Suricat46]

Thanks LongRange for your comments.
Although NDT is widely used (and proven efficient !) in aviation, oil, automotive, etc., I must admit that certain techniques such as FPI, MPI, Eddy Current Inspection, Isotope Inspection, etc. require specific equipment, training and qualification only available in certain laboratories or production or maintenance organisations.
For a "standard" sailing enthusiast doing part of his maintenance himself, the Dye Penetrant Inspection could be a simple, cheap, easy solution to identify cracks on metallic or composite parts, then repair or replace... and build confidence in the hardware of his boat.
DPI is worth for those "critical hardware" parts I was referring to, such ad turnbuckles, chainplates, mast fittings (including welded fittings), cables... Such parts are usually worth far more that a set of 3 cans used in DPI, not to mention the consequences of a failure.
This can also apply to certain shackles (I bet all steel parts on photos developped cracks before breaking loose) or even blocks or fittings on a boom.

FYI a quote to Wikipedia: http://https://en.wikipedia.org/wiki...ant_inspection

and a quote to a simple demo on YouTube:

https://www.youtube.com/watch?v=xEK-c1pkTUI

It will be up to you to develop your own periodic Inspection Program according to your experience and boat utilisation.

Should you find specific defects on parts, it could be a good practice to report to the part manufacturer or boat manufacturer or Naval Architect as applicable.
Sharing with other members of the forum will certainly be welcome ! ;-)

[Brewgyver]

Originally Posted by fxykty

The Harken NZ person I spoke with is Greg Blewett.

I believe you actually mean Grant Blewett?

[fxykty]

Originally Posted by Brewgyver

I believe you actually mean Grant Blewett?

Yes, ooops.

I confirmed with him that the HR breakage mechanism is less deformation before fracture relative to 316 steel, so any deformation of an HR component means failure is imminent. A 316 component on the other hand can deform a fair bit before yielding, and galvanised or other mild steel even more.

[Dockhead]

Originally Posted by fxykty

Yes, ooops.

I confirmed with him that the HR breakage mechanism is less deformation before fracture relative to 316 steel, so any deformation of an HR component means failure is imminent. A 316 component on the other hand can deform a fair bit before yielding, and galvanised or other mild steel even more.

Whether or not that is true, ANY DEFORMATION AT ALL, shows that the device has been overloaded and is undersized for the job. Nota bene!

[fxykty]

Originally Posted by s/v Jedi

I really like Antal and dream I have Karver

I’ve found a local supplier of Karver and pricing looks to be on par with Harken (in NZ). Tempting to go minimalist as fewer things to go wrong. For the round block you showed all the load goes through the centre hole, so a soft becket can be easily made. They also have parts to hang them up for double or triple blocks. Anyone with longer term experience of Karver Round Blocks in particular? The largest one LB12C has a 3000kg SWL and 9000kg BL so looks to be the right size for my running backstay.

Antal have very nice looking gear and they’re almost a third of the price relative to Harken, with pretty much like for like in the Looper blocks.

Does anyone have experience with Ino-Rope? Developed for the Vendee Globe and no bearings - they use a Dyneema axle. More frequent inspection and replacement of the axle but otherwise much lighter and compact than traditional alternatives. I particularly like the Ino-Ending as a running backstay terminator. Does anyone have any experience with Ino-Rope products? Suitable for cruising?