GHA
Well-Known Member
OK, well that makes sense, thought I was probably missing something. Thank you.
Musings on anchor trip line
- Thread starter eddystone
- Start date
jordanbasset
Well-Known Member
My anchor always used to come up the right way then it suddenly started coming up the wrong way. I was told by some one else an easy fix was to go to deep water and let all the chain out and then bring it back in. Not really sure why but it worked and the anchor has come up the right way since.
Neeves
Well-Known Member
I spoke to a surveyor earlier this week and in a younger life he did just that (though I don't recall why he did it). He discovered the windlass was incapable of retrieving all the chain and anchor and he had to labouriously retrieve, 1m at a time, with the main halyard winch.
I was always lead to believe that windlass should always be able to recover all the chain and anchor - obviously not true in every case. If you do it - check the windlass specification first.
And make sure the bitter end is both attached and strongly attached
Like you Jordan I cannot see how this would remove twists - if there are any twists they are between the gypsy and anchor (and you can see them) - you only need to let out a few metres and maybe manually untwist any between gypsy and bow roller. Any twists in the locker will stay in the locker (I have wondered about a swivel at the bitter end) but we use cordage to attach the bitter end to a strong point.
Jonathan
Frank Holden
Well-Known Member
I really am surprised I never ever thought of rotating the chain through 90*... silly me...
Oh thats right I did!!!!
And it worked and then it didn't work and then it did work and then it didn't work etc etc...
If the distance from the gypsy to the crown is an exact number number of links when stowed it will work... well it will work as long as the distance from the gypsy to the crown as the crown arrives at the roller is an exact number of links.
Some may be in this happy situation... many will not.
Big ships use swivels http://www.gard.no/web/updates/content/11831736/loss-of-anchors-and-chain but I am rather surprised how many anchors big ships lose.
Oh thats right I did!!!!
And it worked and then it didn't work and then it did work and then it didn't work etc etc...
If the distance from the gypsy to the crown is an exact number number of links when stowed it will work... well it will work as long as the distance from the gypsy to the crown as the crown arrives at the roller is an exact number of links.
Some may be in this happy situation... many will not.
Big ships use swivels http://www.gard.no/web/updates/content/11831736/loss-of-anchors-and-chain but I am rather surprised how many anchors big ships lose.
NormanS
Well-Known Member
Do you really mean the crown? What's the relevance?
Frank Holden
Well-Known Member
OK...top end of the shank where the crown shackle is attached https://forshipbuilding.com/equipment/anchors/
Something may have been lost in translation.
Edit.... with no swivel fitted it would be the distance from gypsy to top of crown shackle that is critical as that would effectively be fixed in relation to the anchor.
Something may have been lost in translation.
Edit.... with no swivel fitted it would be the distance from gypsy to top of crown shackle that is critical as that would effectively be fixed in relation to the anchor.
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NormanS
Well-Known Member
I learn something new every day.
It seems extraordinary that the "Crown Shackle", as shown in your link, should be at the opposite end of the anchor from the generally accepted "Crown" of the anchor. Sometime when I have time to do the research, I'll see if I can find any corroborating evidence.I am intrigued by your previous statement "it worked, and then it didn't work, and then it worked etc". What exactly do you mean? Unless you have elastic chain, the number of links between the gypsy and the anchor will be the same every time you weigh anchor. So what changes?
Frank Holden
Well-Known Member
I learn something new every day.
I am intrigued by your previous statement "it worked, and then it didn't work, and then it worked etc". What exactly do you mean? Unless you have elastic chain, the number of links between the gypsy and the anchor will be the same every time you weigh anchor. So what changes?
Here you go... some 'corroborating evidence'.. plenty more out there
http://www.iacs.org.uk/document/public/Publications/Resolution_changes/PDF/REC_079_Rev1_pdf2395.pdf
... also known as the anchor shackle but I find that a bit ambiguous. I have also heard it called the 'bending shackle' but I think that may be 'merkin usage. The pin is normally welded in place on big anchors. On my CQR the crown shackle pin was also welded in place 'as built'.
In fact if Rocna and all the rest fitted crown shackles with welded pins at the manufacturing stage then nongs wouldn't go fitting Kongs directly to their anchors.
It would appear that some people are thrice blessed and have anchors that present perfectly at the roller every time. Unfortunately many of us have anchors that do not. Mine would not. Yes same number of links to roller.... a bit of twist in the chain maybe... I honestly don't know... but I do know a swivel has made my life a lot simpler.
It was mentioned earlier that for some reason swivels sell without being advertised. A bit like chopsticks and toothbrushes maybe...
I really should know better than to get involved in anchoring threads when I've just spent 30 hours in a low earth orbit - 12 hours of it in departure lounges and at railway stations.... it always leads to typos and tears.....
PS big ships always have a swivel ....
NormanS
Well-Known Member
I'm not thrice blest, but my anchor always presents on the roller, the right way round. I have a bent link between my Crown Shackle D see), and the chain. As soon as the bent link hits the roller, it automatically rotates the anchor to the correct orientation. No swivels are required for this.
D see), and the chain. As soon as the bent link hits the roller, it automatically rotates the anchor to the correct orientation. No swivels are required for this.
TQA
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Continuing with the Fred Rift both my current Rocna and the previous CQR would occasionally present themselves inverted as they arrived at the anchor roller..
Hakuna matata, just pull them about 1/4 of the way onto the roller, pause for a second to let gravity take over and right the anchor and then pull it home.
Job done.
Hakuna matata, just pull them about 1/4 of the way onto the roller, pause for a second to let gravity take over and right the anchor and then pull it home.
Job done.
thinwater
Well-Known Member
When I do get a 1/2 twist, I simply insert the pin from my chain lock (basically a cut-off Phillips screwdriver) in the chain and rotate the chain the required amount while lowering a few feet. Easy and the fingers are safe.
noelex
Well-Known Member
If you don't use a swivel whenever the boat spins through 360°, it will put a twist in the chain. If anchored for any length of time it is quite common for the anchor to spin when it breaks out to try and unwind the twists.
This can be used to advantage. The idea is to adjust the retrieval speed of the winch so the anchor arrives at the the bow roller the right way around.
It works better if there is reasonable distance between the winch and anchor and if the checks of the bow roller are high and narrow enough to stop the anchor shank twisting once captured. So it is not a technique that works on every boat or on every occasion, but is worth a try. With practice and good timing it is a no fuss way of getting the anchor the right way around.
It is a useful technique that can be used as alternative to other methods that have already been mentioned, such as slowly reversing.
This can be used to advantage. The idea is to adjust the retrieval speed of the winch so the anchor arrives at the the bow roller the right way around.
It works better if there is reasonable distance between the winch and anchor and if the checks of the bow roller are high and narrow enough to stop the anchor shank twisting once captured. So it is not a technique that works on every boat or on every occasion, but is worth a try. With practice and good timing it is a no fuss way of getting the anchor the right way around.
It is a useful technique that can be used as alternative to other methods that have already been mentioned, such as slowly reversing.
Neeves
Well-Known Member
Test show that with 10m of chain it takes around 6-8 complete 360 degree turns before there is sufficient torque for a swival to release twists. Consequently you will always be left with 6-8 twists - if you yacht is making one way 360 degree turns. If there is any chain on the seabed - none of the twists will 'untwist'.
Swivels will not remove all twists.
If your chain is true to start with then allowing the anchor and chain to untwist by itself, anchor hanging freely, should result in the chain returning to true. Depending on the hydrodynamics of the anchor moving forward or backwards, and doing so swiftly, might turn the anchor to the incorrect orientation. Some windlass retrieve so quickly they induce twists.
If you have the time to be be patient then allowing the anchor to hang freely should allow twists to 'untwist'.
Jonathan
Swivels will not remove all twists.
If your chain is true to start with then allowing the anchor and chain to untwist by itself, anchor hanging freely, should result in the chain returning to true. Depending on the hydrodynamics of the anchor moving forward or backwards, and doing so swiftly, might turn the anchor to the incorrect orientation. Some windlass retrieve so quickly they induce twists.
If you have the time to be be patient then allowing the anchor to hang freely should allow twists to 'untwist'.
Jonathan
NormanS
Well-Known Member
It is precisely to avoid having to hang over the bow and twist the chain round with a poker, that some of us have come up with better solutions.
noelex
Well-Known Member
Yes, I can imagine that 6-8 twists over 10m of chain would not generate a lot of torque. However, on occasions a yacht can do many more 360° rotations in flukey wind conditions. The yacht does not have to move around the swing circle, it only has to spin around. Without a swivel nothing can rotate until the anchor breaks out. Once the anchor breaks out it will rotate to untwist the chain, but very occasionally there are enough twists to cause problems before the scope can be reduced enough to break the anchor out.
Fortunately this is a rare problem. The rotations have to be in same direction. But a swivel eliminates any problems.
This is not a great photo, but if look carefully you can see the chain is twisted enough that some of links are starting to become horizontal. If the twists build up further, the chain will start to "hockle". At this stage the anchor is still completely buried so the anchor cannot rotate. As there is no swivel the chain cannot rotate without rotating the anchor.
The anchor winch cannot retrieve severely twisted chain like this. Fortunately in this case the scope was close to 1:1 before the twisting became too much for the anchor winch.
Once the anchor is broken out it will spin (alarmingly rapidly) to remove the twist.
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vyv_cox
Well-Known Member
The first failure diagnosis job I ever did was a Kenter shackle from a tanker. I was told then that if a big ship anchored when doing more than about 1 knot it would break the chain.