Anchor Swivel

[J Neeves]

AndrewG,

I checked you profile but it does not define your location.

For a better choice of shackle in Oz - Whitworths offer HDG CMP (who supply Rocna anchors) bow shackles, for a 3/8th inch shackle, rated at a WLL of 1t. In Sydney another option is anyone supplying lifting slings (and I assume the same will be true in other capital cities) - I have used Sydney Lifting in Brookvale. They stock lifting shackles from Beaver (again a HDG 3/8th inch shackle will be WLL 1t). You can get a bigger range of shackles from Robertsons, various locations (who have the same corporate owners as Beaver). As far as I can ascertain all of these shackles come from China - but they are plus or minus 3/8th inch - so they vary. You can also try 'Chains, Ropes and Anchors' in NZ.

In America you can buy 3/8th inch HDG HT Bow shackles with WLL of 2t, Proof tested to 2 x WLL, and a 6:1 safety factor - but for the life of me I cannot find a way of getting anyone to ship/sell them to Oz.

Crosby in America make a whole cross section of differently designed shackles, recessed pins etc. I have only seen HDG bow shackles with protruding pins in Oz.

If you know someone in America - they could buy and airmail to you quite cheaply - but the various mail order chandlers only know of very expensive couriers and have min order amounts.

I cannot comment on the quality of any of these shackles (available in Oz - I'm in the midst of testing) but if you are using a G30, or Grade L chain (and you size for the chain) then ostensibly they should be adequate - but not adequate for G43 or G40 chain.

Jonathan

 

[NormanS]

If you are only using a swivel because your anchor meets the bow roller 'upside down' then maybe you could consider NormanS' solution of the bent lead, which automatically ensures the anchor addresses the bow roller in the correct orientation (see his earlier posts on this thread). If you follow this route, the 'bent lead' - you will still need Vyv's 3 links - so shank, attached to shackle, 3 links of chain, shackle, bent lead, shackle, chain. (You need 3, 5 or any odd number of links - otherwise the anchor will be upside down again).

If possible I would not put the shackle pin through the shank - it increases the load on the shank (and on the pin), better to allow the shackle to articulate by putting the bow through the shank hole. If you cannot get the bow through the shank hole, you need a different shackle. Shackles seem to be nominally similarly and standard sized - but each type is slightly different, different pin diam, different opening size, shop around. (We are a bit starved of choice, certainly for gal shackles in Oz - and I suspect Europe).

But I am pre-empting Vyv's comments

Jonathan

I don't have any links of chain between the bent link and the anchor. Provided you make it so that the eye on the bent link lies in line with bend, a single bow shackle gives all the articulation required. This will ensure that as soon as the link hits the roller, the anchor will whip round the right way.

This is fine with a bow roller extended out from the bow, giving space for the anchor to turn without hitting the boat. Our previous boat was a converted 60ft MFV with a straight stem, and our 140lb anchor had to be turned manually with a spike through the chain, when the anchor was still under the water, and clear of the stem. This is probably the reason why I am so delighted with the bent link.

 

[J Neeves]

I don't have any links of chain between the bent link and the anchor. Provided you make it so that the eye on the bent link lies in line with bend, a single bow shackle gives all the articulation required. This will ensure that as soon as the link hits the roller, the anchor will whip round the right way.

This is fine with a bow roller extended out from the bow, giving space for the anchor to turn without hitting the boat. Our previous boat was a converted 60ft MFV with a straight stem, and our 140lb anchor had to be turned manually with a spike through the chain, when the anchor was still under the water, and clear of the stem. This is probably the reason why I am so delighted with the bent link.

Vyv seemed to find that the links were necessary, with a swivel, and I was not sure that a 'bent link' might not be similar. Having links ensures that if the shackle jambs there is still plenty of articulation. Having links keeps the whipping anchor further away from the bow. But this might be unnecessary belt and braces

But as you say of your bent link - what's not to like? Its cheap, it works, its simple and provided it strong enough - its safe.

Jonathan

 

[NormanS]

Vyv seemed to find that the links were necessary, with a swivel, and I was not sure that a 'bent link' might not be similar. Having links ensures that if the shackle jambs there is still plenty of articulation. Having links keeps the whipping anchor further away from the bow. But this might be unnecessary belt and braces

But as you say of your bent link - what's not to like? Its cheap, it works, its simple and provided it strong enough - its safe.

Jonathan

I think the reason that Vyv rightly advocated the use of three links was where using a swivel with a jaw attachment, meant that without the links there would be an unfair loading on the swivel. With a link with eyes, there should be no problem.
Over to Vyv.

 

[estarzinger]

.
The solution was simple - "The Twist"

I don't have any need for a regular swivel (in fact I had one of the expensive shinny ones break on me in Hurricane Lenny) but that looks useful. Where does one buy it (I am in the USA, but happy to get it shipped internationally if the store will do it)? Osculati's on-line store is for wholesale customers only.

EDIT: ordered one from Piplers of Poole

Someone should distribute these in the US - way less expensive than that Ultra swivel.

 

[vyv_cox]

I think the reason that Vyv rightly advocated the use of three links was where using a swivel with a jaw attachment, meant that without the links there would be an unfair loading on the swivel. With a link with eyes, there should be no problem.
Over to Vyv.

Yes, I think that with eyes there would not be the same problem. I only realised that a shackle plus a jaw type swivel was a problem when the anchor came up several times with the swivel wedged against the shank, as shown on the website. An eye and shackle seems a more sensible arrangement but of course it isn't as sexy.

 

[Anders_P42]

An interesting thread, I'm buying 15KG Rocna do I need the Osculati twist?

What's the part number for the Wichard 17/4PH countersunk shackle for 8mm chain?

Anders

 

[Andrew G]

Vyv, Jonathan et al, thanks for your replies to my questions.
Any ideas where one might get a bent link in Aus (or shipped to Aus)? (I'd prefer just a bent link with no built-in swivel unless it were absolutely secure).
I’m currently thinking - 8mm chain/headless shackle (unless link has one built-in)/bent link/headless shackle (unless link has one built-in)/3 links of 10mm chain/headless shackle/anchor.
I’m quite confident that the anchor would flip with the 3 links in and that I have enough distance between the roller and windlass.
This would be secure, should work, but would be expensive and possibly overkill . . .
Cheers, Andrew

 

[J Neeves]

Its interesting - the ones on sale (and a number of suppliers make a bent link with swivel) are very expensive. They also incorporate a swivel which may of may not be desirable and the swivel may or may not actually work.

But based on NormanS design you could buy a small length of stainless plate, cut one out, drill two holes at each and (and file them into a nice oval to take the eye of the shackle) and you would have a bent link. It would cost very little, needs an angle grinder, decent drill and a wet Saturday. You could make the same from a higher tensile steel (which would be a preferred option) but it then needs galvanising which may or may not be convenient.

Go to many other threads and a common theme is cost.

I now have one, yet to be galvanised, cut from a piece of Bis80. Mine is a bit big as I only had 12mm plate but works a treat, I'm now looking for thinner plate (8mm) - to quote NormanS, 'what's not to like'.

Evan - there's a business tucked in there somewhere - someone in America buying and shipping impossible to buy parts for Europeans and a European buying and shipping same from Europe (saving the sales tax in Europe ought to make it worthwhile).

Jonathan

Edit, Andrew, our posts crossed - this might answer the question. For a small bit of Bis80, many laser or water cutters will have stock of scrap pieces and you only need about 60mm x 120mm. Just make sure its a HT steel. Its not difficult to work (though the filing is a bit laborious.

 

[Andrew G]

Jonathan,
"I now have one, yet to be galvanised, cut from a piece of Bis80. Mine is a bit big as I only had 12mm plate but works a treat . . ." Any chance of a pic. I'm struggling to see how a piece of flat will flip within the roller??. Cheers, Andrew (PS I sent you a PM)

 

[J Neeves]

Pics take a bit longer And longer still if you want it on all set up on the bow

We have a 'V' bow roller. But even a flat roller would do the same. As soon as the bent link fits the roller it turns such that it bends down, something to do with the anchor being heavy.

Jonathan

 

[J Neeves]

Sexy fittings

I tried to send this earlier and lost it!

I do not have a spare bow roller at home, so please excuse the simulation

From left to right:

8mm G8 chain; Campbell HT, 3/8th inch gal bow shackle WLL 2t; 12mm bent link Bis 80; 1/4 inch Peerless HT bow shackle WLL 3/4t zinc coated; 3 links G8 chain; 3/8th inch Peerless HT bow shackle zinc coated WLL 2t, Spade alloy shank (fluke not attached).

The bent link is unstable in any orientation on the bow roller except as shown.

I only include the cross section of shackles to show what is missing from our choice, in Europe and Australia.

I may make another model in 8mm plate as this might be more to scale for the fittings and our chain, 8mm G3.

The bent link is yet to be galvanised and is the least sexy marine item I can think of and certainly will not compete with a sexy Italian. But its cheap, cheerful, it works and has no, unnecessary(?), moving parts.

We have tried the bent link with 11 links between anchor and bent link. It works perfectly.

I constantly change anchors - so like the convenience of the protruding pins.

Jonathan

 

[Andrew G]

Thanks Jonathan. That sure is a lot of grinding, drilling and filing but it clearly works, and 100% it should for me – I’ll get some 8mm stainless and give it a go (I'll leave a little more meat around the holes and may make the anchor section a little longer than yours - I'll play with plywood mockups first. My chain is only 8mm short link). Cheers, Andrew

 

[noelex]

The best news is unlike the commercial models it does not look like it would be more at home in the bedside table

 

[J Neeves]

And those who covet it will have knowledge and integrity so being so ugly no-one is going to steal it

Jonathan

 

[J Neeves]

Thanks Jonathan. That sure is a lot of grinding, drilling and filing but it clearly works, and 100% it should for me – I’ll get some 8mm stainless and give it a go (I'll leave a little more meat around the holes and may make the anchor section a little longer than yours - I'll play with plywood mockups first. My chain is only 8mm short link). Cheers, Andrew

Its less cutting and grinding than you might think, it can be made from a 60mm wide piece (overall its 180mm long), so you cut off the 'top' smaller triangles and then the bigger one in the bottom. You will need to either drill the apex of the bottom triangle or cut with a hacksaw - you cannot get an angle grinder in there. Do not make the angle too sharp, mine is 140 degrees, if you went to, say 110 - it would be a sharp hit on the bow roller. I drilled 2 overlapping 12mm holes at each end and then filed them into one each (at each end). You then need to choose your shackles (and you can get 3/8th bow lifting gal shackles here (Oz) WLL at 1t (so fine for an 8mm G30 chain). You then need to fit the shackles so they swing freely, which means taking a bullnose (?) round the 2 holes to get a clean fit. 8mm stainless might be beefy enough for the 'shank' - as you say you might want to make the steel round the holes bigger then mine (stainless is not that strong - but then its only going to be in tension). The ends and the underside might advantageously be rounded, its those surfaces that will be the working surfaces when you set the anchor. You can leave the top flat.

If you are adept with an angle grinder you will be able to finish off quite neatly (and quickly) with a grinding wheel - I'm not that practised and know one slip will make a real mess, so I did spend some time filing.

But it does not take that long

I made a number of prototypes with MDF - I suspect you could make it shorter than my 180mm - but the Bis 80 I had allowed that length at the 140 degrees.

If I get a piece of 8mm Bis 80 I would keep the dimensions at the end the same but make the shank parts a bit thinner.

Jonathan

 

[noelex]

Johnathan has it tested on a typical monohull setup with the anchor gypsy close to anchor.? No swivelling action on the plate will tend to force the plate to lie in whatever position the chain coming off the gypsy dictates. Particularly with gypsy forcing the plate in horizontal position (90 degrees from the position shown) the righting force is not be high without a rigid connection to the anchor shank.

It is always difficult to imagine these 3 dimensional engineering problems so some testing would with a gypsy would help resolve the question.

Happy to be wrong. It looks like a cheap strong solution which is a great combination.

Also before you make one check there is enough distance between the end of anchor shank and the windlass, or chain stopper. The commercial models are quite long and don't fit many boats. This home made version looks a bit shorter which should be an advantage, but there will still be some boats with not enough room.

 

[NormanS]

I tried to send this earlier and lost it!

I do not have a spare bow roller at home, so please excuse the simulation

From left to right:

8mm G8 chain; Campbell HT, 3/8th inch gal bow shackle WLL 2t; 12mm bent link Bis 80; 1/4 inch Peerless HT bow shackle WLL 3/4t zinc coated; 3 links G8 chain; 3/8th inch Peerless HT bow shackle zinc coated WLL 2t, Spade alloy shank (fluke not attached).

The bent link is unstable in any orientation on the bow roller except as shown.

I only include the cross section of shackles to show what is missing from our choice, in Europe and Australia.

I may make another model in 8mm plate as this might be more to scale for the fittings and our chain, 8mm G3.

The bent link is yet to be galvanised and is the least sexy marine item I can think of and certainly will not compete with a sexy Italian. But its cheap, cheerful, it works and has no, unnecessary(?), moving parts.

We have tried the bent link with 11 links between anchor and bent link. It works perfectly.

I constantly change anchors - so like the convenience of the protruding pins.

Jonathan

That looks fine to me. The simpler, the better. As I say, I made mine using round bar. The eyes were made from chain links, with an end hacksawed out, and then welded to the round bar. One of the plus points of this system is that it is decidedly "Low Tech", with no moving parts.
Someone was in touch about it a while ago, and was considering welding the last few links of chain, next to the anchor, into a curve. This would obviously achieve the same result, but welding galvanised chain brings in other considerations. He was going to let me know how he got on with it.

 

[estarzinger]

I looked into making a bent link . . . I was going to use round stainless bar and bend it with hydraulics. Would not have been hard or expensive. I thought bending round bar was better than cutting flat plate because it would be smoother on the roller.

But I concluded that the swivel feature might actually be important here. When the bent link hits the bow roller, it is going to put a sudden 180 degree twist in the chain. And that twist is going to be in the relatively short distance between the bent link and the gypsy. I thought that might well cause gypsy/chain problem.

 

[J Neeves]

There was an error in my post on dimensions, thanks Andrew, the length is 180mm - I've corrected the post.

If you have a short distance between windlass and anchor shackle when the anchor is secured then a bent link simply will not fit. Mine is 180mm long plus at least one extra shackle - which is, in total, about 220mm. If you do not have that 'space' then my bent link would not fit - though I would not give up, a shorter bent link might work. I an not suggesting my dimensions are the 'only' answer, just ones that worked for me. NormanS, you might have posted earlier - what are the dimensions of yours?

I went the plate route simply because I have no welding facility (and was not prepared to pay for welding and then find it was not 'quite right'). Most people can cut and drill - plate seemed a simple solution - and cutting and drilling Bis 80 is not difficult (or not for small pieces). I'm not keen on stainless - only because people might cut corners and make the device too small for the strength of some stainless. For the initiated - stainless is not an issue. My 140 degree bend offers a smooth entry, I could have ground a curve, but that was 'real' time

The bent link introduces, or takes out half a turn of the rode - and quickly checking - its a bit tight but 3 x 8mm links will take half a turn. Based on my dimensions you need 320mm between the end of the shackle on the anchor and the gypsy. Within the 320mm you can fit, my bent link + 1 extra shackle + 3 links taking up the 180 degree to 'right' the anchor. The load on the gypsy with this half turn on 3 links is negligible (and maybe my bent link is too long). For bigger chain, 10mm or 12mm you would need a bit longer (for bigger shackles and bigger chain) but the bent link is certainly going to be strong enough!

I'm not keen on swivels, often you do not know what they are made from, you do not know (because they are contained and hidden in a barrel) what state they are in, you often do not know how big the swivel is (its hidden). Many people mention that though they have swivels their anchor rotates when it is freely rising (suggesting swivels actually might not work). I'm not sure that when buried in sand, everyone mentions how their anchor is buried deeply, that the seabed might not 'lock up' the swivel and or enjoy great abrasion. For what they are stainless swivels are extortionate. If the swivel is only to turn the anchor at the bow roller - there must be a cheaper way? I'm very happy to be convinced that I am too parsimonious!

The bent link cannot put much of a load on the gypsy when the link hits the roller - the length of chain between roller and gypsy is longer than the shank and if 3 links can take half a turn - then the number of links in the length of the shank (+3 links) will absorb that twist easily. In any event, without the bent link - unless you orientate the anchor by hand there will be a much greater impact on the gypsy, windlass and roller if the anchor hits the roller 'upside down' and self rights. If there is concern at the impact of the selfrighting of the bent link - leaving it to its own devices is worse.

I know some rollers are not as simple as mine, ours is a simple 'V'. You would need to ensure that whatever bent link you use - it actually fits and will not lock into the roller.

As with anything to do with anchors its a compromise, there is never - one size fits all - its taking a solution and fitting it to your specifics, hopefully a solution might fit a few installations and another similar solutiona few different installations.

Jonathan