MurrayM
Guru
Also subtract about 15 percent strength if it's wet (nylon loses strength when wet) minus more if there's cyclic loading, minus a bit more if heat is being generated by friction...sleep tight
This discussion was started by Diver Dave's comment that one should use a snubber to protect a swivel. It has nothing to do with other benefits snubbers provide. I maintain that a swivel should NOT be the weak link in anybody's ground tackle.
My chain is Acco's G4, 5/16", galvanized of course. My swivel? Heck the last time I saw it was prior to hauling time last October so I cannot related it from memory to what now is offered by West Marine. Years ago I had another heavy beast swivel that used a clevis pin which I had welded to prevent it from ever pulling out. Personally, I would not consider a SS swivel.
Also subtract about 15 percent strength if it's wet (nylon loses strength when wet) minus more if there's cyclic loading, minus a bit more if heat is being generated by friction...sleep tight
The non SS 5/16" swivels West Marine sells have WLL of around 1500#. Great candidate for protection with a nice stretchy snub line.
A SS Ultra for that size chain and up to a 77# anchor has a WLL of around 5,000#.
But....I'm a little confused here...but if the rolling hitch breaks....your boat is still secured, its just now an all chain rode and you'd probably feel that in the boat if you lost your snubber....right ? IOW...its not a critical failure if the rolling hitch breaks...more of an inconvenience.
In any system, there WILL be the weakest link. When that weak point becomes the deck, I would be concerned.
I remember thinking when I purchased the swivel that it would rip my Maxwell HWC2200 windless from the deck before the swivel would fail.
As long as the 40% reduction in strength a rolling hitch results in doesn't bother you, then no problem.
Keep in mind that that a chain hook also reduces the strength of the chain....
Could you explain how the chain is weakened by the chain hook? I see how the entire snubber system...chain hook (or rolling hitch) and nylon line...carry lower tensile ratings than the rode itself, but how does the chain hook weaken the chain?
I had stainless plates under windlass and all cleats on that boat. Was off the boat at the time but i’ll bet the foredeck took quite the deflection.
I don`t like the idea of the whole weight being on one hook on a line inserted into a link. Much more comfortable with the Sea Dog type ss plate with U shaped cut where the chain sits in the U, with 2 lines from the plate taking load back to the mooring cleat. I think/hope that better distributes the load.
There was a report in Practical Sailor a few years ago. They found that any of the then current chain hooks weakened the chain. It had to do with the stress the hook places on the links. A google search should find the article.
The article concludes that "the argument that a chain hook attached to a properly-sized nylon snubber might weaken the chain and cause a catastrophe is flawed. This is why hooks have been used for decades without an issue."