Anchor shackle

PuffTheMagicDragon

PuffTheMagicDragon

Well-Known Member
Joined
16 May 2001
Messages
14,403
Visit site
Is there any logical reason why there is a bow shackle to attach the chain to an anchor? A 'D' shackle would be easier to pass between the cheeks of the bow roller while the bow-type tends to jam and prevents the CQR to self-stow. I will be replacing mine next Monday and, unless I am convinced otherwise, I am tempted to put a plain 'D' type. Any preference as to whether Stainless or galvanised? Present one is galvanised...as are the anchor and the chain.

Thanks.
 
You may like to look at the anchoring pages on my website for a lot of information about shackles, connectors, etc. With very few exceptions I found that stainless steel shackles are stronger than galvanised ones, with better reliability.

So far as the configuration is concerned, I have always used a D shackle, which passes through my bow roller more cleanly. I doubt very much that there is a significant difference in performance between the two shapes.
 
albineer said:
A bow shackle can cope with sideways loads better than a D shackle according to this web site. Makes sens to me.
http://www.beyondrigging.com/2013/12/bow-shackle-and-d-shackle/
Click to expand...


At first glance that seems to be the conclusion that most people reach. However, any sideways pull will first act on the pin that passes through the hole in the shank, and then the shank will turn in the direction of the pull until it is aligned...at which point there will be no difference between a 'Dee' type and its 'Bow' equivalent. IMHO.
 
vyv_cox said:
You may like to look at the anchoring pages on my website for a lot of information about shackles, connectors, etc. With very few exceptions I found that stainless steel shackles are stronger than galvanised ones, with better reliability.

So far as the configuration is concerned, I have always used a D shackle, which passes through my bow roller more cleanly. I doubt very much that there is a significant difference in performance between the two shapes.
Click to expand...

That has been my reasoning as far as the shape is concerned. Regarding the material I was not too sure about stainless, mainly because of the possibility of 'catastrophic failure'. The only ones to have a reliable SWL seem to be the Wichard shackles...which come with a Wichard price tag!
 
The Wichard 17/4PH shackles are more expensive than 300 series ones, but not by comparison with your boat, or even your anchor. An extremely worthwhile investment IMO.

I have been taking a lot of underwater photos of anchors this season and found very little evidence of sideways loading. During windshifts the shank invariably turns the flukes unless the wind is very light. No doubt there can be the exception if the anchor is trapped in rocks but this is pretty rare and even then would probably not be damaging to the shackle.
 
PMD - you may have a bit of fun with this galvanic table :)


http://corrosion-doctors.org/Definitions/galvanic-series.htm


Most of the anchor shackles I have looked at recently (I'm rebuilding the front of the forestay system) have been stainless, and a bit bulkier than the galvanised chain.

I like the idea of the protective sleeve, but how durable are they with a multi-tonne snubbing load ? Would a piece of stainless tube serve you better ?
 
Galvanic corrosion is never going to be a problem with anchor equipment. After having a stainless connector with galvanised chain and anchor for the past five(?) years, the worst that has happened is that the last two or three chain links have lost some of their galvanising.
 
VC, I was not suggesting any ss:galv corrosion issues, honestly. I had just found the info and it's far more comprehensive than Nigel Calder's, and interesting to find the differences in nobility and how it is explained in their website pages.

The pics alone make the site worth a visit. They are almost as good as yours... :)
 
Last edited:
vyv_cox said:
The Wichard 17/4PH shackles are more expensive than 300 series ones, but not by comparison with your boat, or even your anchor. An extremely worthwhile investment IMO.
Click to expand...

No doubt about that!

But then there is also the old maxim that something is "only as strong as the weakest link" in the sense that, since the chain itself is an 8mm galvanised, wouldn't a 12mm stainless shackle (required to provide the 25mm gap for the shank) be an 'overkill'? In that situation, are there any technical reasons for preferring stainless over a normal galvanised shackle? I am trying to look at it from an engineering point of view; in the grand scheme of things the cost is not really material.
 
The 12mm size is necessary for the 25mm gap between the ends of the shackle that will allow it to fit over the end of the shank, the shackle pin passing through the hole in the shank. Attachment to the chain itself is via another smaller shackle, back to back, with the pin of the smaller shackle passing through the end link of the chain. This is what I have at the moment except that the one on the anchor shank is a bulky galvanised bow shackle...which is what I would like to replace.
 
There is a lot of discussion about anchor shackles, but I think it is an important subject. It is a shame to end up with the least expensive component of the anchoring system as the weakest link. With the low cost of shackles and possibility of oblique angle of pull there is some motivation for buying the best even if it is overkill.

A galvanised hi test bow shackle from a reputable company with the pin partially cut off is my solution. The rounded slightly wider shape of the bowed shackle body stops the remnants of the pin catching. The shackle can still be moused rather than glued. It can reasonably inexpensively be replaced every couple of years and there are no galvanic problems.

There are flush pin shackles which slide through the bow roller better, but they are difficult to get with only a limited number of options. The Whichard 17.4 PH shackles are one option. In may ways they tick most boxes. They are made by a reputable company are very strong and some come with a flush pin. There is some question mark over their susceptibility to corrosion. The 620 stainless steel used is very strong, but is more prone to corrosion than 316.

Whichard say the following:
"Corrosion attacks stainless steel and is always visible in the form of black coloured roughness. Although this is dangerous, it is rarely seen in current use, except in cases where martensitic (HR) steel is in total, prolonged immersion."

Note that they single out only the HR stainless steel for this warning.

There is some debate about what constitutes "prolonged immersion" many feel this only applies to moorings, others offer the view that it is not appropriate for anchor gear. I am really not qualified to comment, but it is a warning that you should be aware of.

As I anchor sometimes for a week at a time with the anchor shackle usually buried under the substrate so I am more concerned about the issue of crevice corrosion than most.

The photo shows the Crosby G-209A shackle I use. There are similar models from Green Pin. It is very strong (G8 steel). I cut the ends of the pin off and drill a small hole so the shackle is more flush, but can still be moused. You can cut them more flush than this and still have room for a mousing wire, but they become a bit more difficult to remove.
 
Last edited:
You must log in or register to reply here.

Share this page

Top