Snap shackles not advisable for snubbers.
In regard to your ongoing investigations of snubber hooks (“Snubber Chain Hooks Revisited,” February 2017), I want to add another idea to the mix. Our boat uses a fixed eye snap shackle spliced onto the end of a three-strand nylon snubber. Our shackle is similar to this Wichard’s 2 ¾-inch fixed eye snap shackle (part #2472).
Can Practical Sailor offer insight on the relationship between the size of the clear opening in various chain sizes and the rated loads of such snap shackles as fit through those openings? Our shackle looks fairly robust, but it requires a bit of fiddling to pass the open shackle through the chain opening (I doubt the next size up would fit) and I wonder if a suitably strong shackle simply may not exist. Some quick release shackles, notably Tylaska’s employ a design in which the opening side has no large ring on the end, as pin-type shackles do. Presumably a given chain can accept a shackle like the T8 (or a Tylaska J-lock) with a higher working load than the largest pin-type shackle that will fit.
S/V Flying Moose
Your snap shackle is probably the Wichard fixed eye 2 ¾ (70 mm) snap shackle with a published working load of 2,820 pounds (1,280 kilograms) and an ultimate tensile strength (UTS) of 6,600 pounds (3,000 kilograms). Based on these specifications, the snap shackle’s working load would exceed that of 1/4-inch high test G43 chain or galvanized 3/8-inch G30 proof coil, each of which have published working loads of about 2,600 pounds/ 1180 kilograms.
However, we would not recommend this type of hook for this use. The hook’s geometry isn’t well suited for being used as snubber hook and the design is not as strong as other, simpler hooks we have tested. It is also very expensive compared to general purpose lifting hooks like we reported on in our test.
The Tylaska hook you mention is even stronger, but it also would not be a cost effective choice for this use. Here’s what Tim Tylaska, the company president had to say:
“We looked into making a shackle that would fit through typical chain that you might use (say 3/8 BBB) and there was not a whole lot of real estate there to allow you to fit a very beefy shackle arm. If (or when) the chain ever binds or twists around the arm of a shackle that is passed through a chain link, the resulting torque on the arm seemed to be enough to bend most anything.
We tried various approaches such as making a clip that hooked around the outside of the chain, but during a severe wrap up of the chain this would also bend or come off. What we finally came up with that was strong enough basically looked like a chain grab hook that had a locking pin.
It was not very attractive, and was in fact very close to looking EXACTLY like a chain grab hook with a locking pin. As the project progressed, we decided to why not just make a commercial stainless industrial hook (the LH10, $445) that could be used by all lifting industries and thus have a huge market base versus this very specialized hook for use a chain snubber that would have almost no market.”
Although the price puts it out of reach of most sailors, the L10 is a certified forged lifting hook and is now being used on numerous commercial fishing vessels. Tylaska said he would let us know if they came up with a different design. In the meantime, stick with hooks from our February 2017 report.