Working load for anchor shackle

[Palarran]

Last year I bought a new Rocna 55 kilo anchor. I removed the swivel that the previous owner had put on and have not had any problems with the anchor twisting. But the large Wichard bow shackle ear would catch on the bow roller. So I bought a new very large shackle from a marine store in Corfu that has an allen head pin. It is beefy but didn't have any stamping for working or breaking loads. It works fine with the bow roller but I'm somewhat concerned about it's unknown strength.

Wichard makes a similar shackle:
Shackle / self-locking / allen head pin

It has a working load of 4600 lbs and a breaking load of 13,000 lbs. My chain is 13mm and the boat, a catamaran, weights around 25 tons.

My other option is to use Noelex's idea of cutting the ears off a larger shackle, but I'd like to use this one if possible.

Is this shackle large enough? I've search the CF archives and can't find any reference to actually sizing shackles. Advice would be appreciated.

[model 10]

Are you using an oversize shackle that has a pin that just barely fits in the chain?

[Palarran]

The Greek, non-rated one matches that description.

[SailFastTri]

I wouldn't use stainless shackles for an anchor or mooring. The image below isn't mine but I've had a similar breakage on a small shackle used on the genoa. Stainless is subject to fractures that are less likely in Galvanized steel.

[noelex 77]

The most important think is to use a name brand shackle with good QC and defined specifications, which you are doing.

Given the low cost of the shackle I think its also desirable that it has a higher working load and break load than the chain.

12-13mm G3 to G4 chain (sometimes G3 chain is actually G4) has a WL around 2100-2400 kg and a break load of around 8000-9000kg.

The Whichard shackle has a WL of 2080kg and a break load 5987 kg.

In practice this is fine, and you certainly doing much better than most boats that use a no name shackle.
However, the 1/2 inch Crosby G-209A has a WL of 3300kg and a break load of 14,985 kg and would be a better choice. It ensures that the shackle does not become the weak link, especially as some degree of side loading is possible, which reduces the shackle strength.

There is no need to become paranoid, chain and shackles rarely break, but I still think its a shame to make the smallest/cheapest component potentially the weakest link.

I have just ordered some Crosby alloy shackles from Jonjo's link of tecnilift.
Crosby Lifting Equipment, Yale Electric Chain Hoists, Kuplex Chain Slings, Tirfor Cable Pullers, Shackles, Eyebolts, Tractel Height Safety Equipment
Delivery in Europe was quick and easy.

Get the hacksaw out to chop off the large head to the pin

[Palarran]

I appreciate that but what I'm really looking for is how to figure out what the working load should be for a shackle with a catamaran weighing 25 tons.

[noelex 77]

Originally Posted by Palarran

I appreciate that but what I'm really looking for is how to figure out what the working load should be for a shackle with a catamaran weighing 25 tons.

That is a good question.
Practical measurements of anchoring loads (using load cells) are low, which does not fit in with the observation that even reasonably set anchors will sometimes drag in stronger wind.

Anchor tests have shown that good new generation anchor sized for about a 40 foot monohull (35lbs) will hold in excess of 2500kg.

Using the Whichard shackle that is rated with a WL of 2080 kg and a break load of 5987kg ( and less for sideways pull) on a 120 lb anchor means that on some (many?) occasions the shackle would be weaker than holding power of the anchor, which seems a poor choice for such a small and cheap component.

In practice, even weak no name shackles rarely break which is one of the puzzles. The theory and practice do not make sense to me.
The safest option seems to fit the strongest shackle, even if it is probably overkill.

[Palarran]

Originally Posted by noelex 77

However, the 1/2 inch Crosby G-209A has a WL of 3300kg and a break load of 14,985 kg and would be a better choice.

Thanks Noelex. So this one:
Amazon.com: Crosby G209A 3.30Ta Screw Pin Anchor Shackle 1/2" (1017494): Industrial & Scientific

In hindsight, the key was the working load of the chain. Don't know why I didn't look that up, duh.

[Palarran]

Originally Posted by noelex 77

Using the Whichard shackle that is rated with a WL of 2080 kg and a break load of 5987kg ( and less for sideways pull) on a 120 lb anchor means that on some (many?) occasions the shackle would be weaker than holding power of the anchor, which seems a poor choice for such a small and cheap component.

The Rocna is a monster. After dragging anchor in several harbors in France two years ago I had to replace my old Delta 25kg. Obviously too small. Once I get this shackle situation 100% right, ground tackle can be removed from my fear list. It's too long of a list to not eliminate the easy things.

[Palarran]

I ordered a Crosby 1/2" and 5/8" because I don't know which will fit the chain. For $50 bucks whoppteedoo. Thanks.

[Stu Jackson]

Anchor System Sizing Tables (Reply #6) Ground Tackle & Anchor System Sizing TABLES & Swivels

The tables in this link might help. Don't know what the windage would be for a multihull since the tables seem to be for monohulls. But you can use the load capacities to cross check.

[DoubleWhisky]

Originally Posted by Palarran

After dragging anchor in several harbors in France two years ago I had to replace my old Delta 25kg. Obviously too small.

One more of mysteries of Delta recommended sizing
For Your boat You do obviously need nothing less than 40 kg new gen (SHHP) anchor, so for Delta (HHP) You need more than 50 kg at least, but 25 kg is in accordance with Lewmar sizing chart.
May be we should call Delta NHLA (not holding like advertised) anchor?

Originally Posted by Palarran

The Rocna is a monster.

Monster or not, You can sleep well now
It is sized as hurricane anchor for Your boat.
You can only have a not so easy retrieval from time to time, after prolonged anchoring

Good buy!

Tomasz

[JPA Cate]

Obviously, the shackle cannot be moused. So, will you use Locktite? Which grade? Will you be able to trust it? I'm not smarting off here, we've just always used shackles with a hole in the pin and mouse them.

Ann

[Palarran]

Stu, that was really helpful. So with 60 knots of wind I can expect at least 10,000 lbs of force. That seems reasonable. I know in 40 knots that chain is REALLY tight.
Thanks.

[Palarran]

Originally Posted by Ann T. Cate

Obviously, the shackle cannot be moused. So, will you use Locktite? Which grade? Will you be able to trust it? I'm not smarting off here, we've just always used shackles with a hole in the pin and mouse them.

Ann

Good point. This is what Wichard says:
Commentary

• Self-locking twisted shackle with allen head pin forged in grade 316L stainless steel
• The pin is locked into one of the indentations
• The head of the pin does not stick out from the shackle body and thus eliminates any risk of snagging
• No risks of loose due to vibrations
• Outstanding working and breaking loads

You would think Wichard knows what their talking about.