Anchor slot/hole

For years I've noticed most anchors have a hole in the end of the shank for the shackle and many others have a slot and Ive been curious what the reason would be for a slot. I've always attached the shackle w the pin through the hole/slot of the shank*** ..seemingly the only logical way to do it but now it occurs to me that one could probably put the ear on the horseshoe part of the shackle through*the slot. I like to put the biggest pin through the shank hole that will fit so the shackle won't move sideways and try to bend the shank. I like to have a fairly close fit shackle pin to shank hole. I notice there is a "anchor shackle" that has a larger dia "horseshoe" that appears to be designed to take sideways pull from the rode. Could it be that the slot is there to pass the "ear" of the shackle horseshoe end through the shank? Would that reduce bending forces on the shank? *If not WHY do some anchors provide the slot? In view of the fact that it's more trouble to make a slot there must be a reason for it.

The Rocna has a slot. While I have not talked to them about the reasoning for this, their illustrated manner of attaching the rode is to put the closed end of a shackle through the slot with the pin through the chain. The only way to feed a shackle through the shank is with a wider hole, or slot.

The benefit of putting the closed end of the shackle through the shank rather than the pin is that if the closed end is in the shank the shackle is free to rotate in any direction and align the shackle pin with the load. In other words, with the closed end of the shackle attached to the anchor shank there are no sideways loads on any component of the rode. The pull is always going straight through the shackle as opposed to a sideways load being applied to the pin, which could be the case if the shackle was attached to the anchor with the pin.

In reality it's probably a pretty subtle point since I would think it would take a heck of a side load to damage the pin of a properly-sized shackle.

That's the only reason I can think of. You can always call Rocna in New Zealand and ask them. It's been a number of years since we acquired ours, but at the time the folks at Rocna were quite helpful when I had questions.

I don't see the functional difference between the shackle rotating on the shank or the anchor*chain rotating on the shackle.* I still think it is a marketing ploy.

markpierce wrote:

I don't see the functional difference between the shackle rotating on the shank or the anchor*chain rotating on the shackle.* I still think it is a marketing ploy.

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If the shackle rotates or pivots on the shank, the load on the pin will always be at right angles to the pin.* There will be no shear load on the pin.* If the pin is in the shank and the load shifts out of line with the shank, which it invariably does, the chain will be angled off to the side of the anchor but the shackle will remained lined up with the shank because of the straight pin through the hole.* So the load on the pin will now be a shearing load as opposed to a straight load.

I don't see any marketing advantage to providing a slot vs a hole.* I think it's more to do with what the anchor designer felt provides the optimum setup.* I don't think it has anything to do with new generation anchor vs old generation anchor, eiher. Our POS Bruce which is now propping open a door in our garage is a very old design by today's standards and it has a slot, too, just like the Rocna.

How susceptible a shackle pin would be to damage with a shearing load is something I cannot hazard a guess on.* But it's the only reason I can think of for providing a way to attach the closed end of a shackle to an anchor as opposed to attaching the open end with a pin.


-- Edited by Marin on Thursday 20th of January 2011 01:56:00 PM

Thanks, Marin.* I see it now.*

Marin wrote:I don't see any marketing advantage to providing a slot vs a hole.* --*

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*It has little to do with marketing. The slot is there so that a single shackle can be used to connect the chain to the shank rather than having to use two shackles because the lugs won't pass through the link, especially if it is studded chain.

Rick,
What's a "lug" and what's a "studded chain"?

RickB wrote:The slot is there so that a single shackle can be used to connect the chain to the shank rather than having to use two shackles because the lugs won't pass through the link, especially if it is studded chain.

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I had forgotten this advantage even though we took advantage of it.* In the first photo below you will see that the Rocna is connected to the rode with two shackles.* Then I read the directions that came with the anchor and realized that by putting the closed end of one shackle through the anchor shank I could elminate the second shackle.* The fewer components in an anchor system the better in my opinion.* So that's the way it's set up now. (second photo).

The bungee is there due to my lack of observational powers.* For all the years we've had the Rocna I believed (and said in posts) that the Rocna sits this way, with the shank up in the air.* Wrongo.* The* ass-in-the-air attitude makes it a breeze to deploy--- I just start letting out rode and off it goes.* But I just recently realized it's being held in this position by the bail or keeper over the front of the shank. It's too short to let the anchor lie back properly with its shank down in the pulpit channel.* So I've made a new, taller bail and once I put it on--- hopefully this weekend--- the Rocna will sit solidly into the pulpit channel and behave itself and I can dispense with the bungee.

*

nomadwilly wrote:

Rick,
What's a "lug" and what's a "studded chain"?

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I believe the lug is the wider portion of the shackle legs that the pin goes through on one side and threads into on the other side.

*

nomadwilly wrote:What's a "lug" and what's a "studded chain"?

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Marin got the "lug" correctly. A "studded chain" is what you sometimes need on your tires to drive the Columbia Gorge in winter.

Not really, it is the type of chain that has the cross piece in the center of a link to help stiffen the links and it also helps prevent tangling by limiting the amount of travel between links.

*


-- Edited by RickB on Thursday 20th of January 2011 03:01:21 PM

Ya Know,I just learn a lot from you all,thanks, little things add up and it all helps. BB

belizebill wrote:
Ya Know,I just learn a lot from you all,thanks, little things add up and it all helps. BB

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Now BB, just when you thought it all worked out re these slots, I havdatellya, there are slots, and then there are SLOTS...........now what do you think this slot is for......?
Sorry Marin, Eric et al, but I couldn't resist......



*

More to the point, what do you think it is for?

Perhaps one could hook a bouy in that slot.BB

So PB has the BIGGEST SLOT! I'll find something on my boat that is the biggest, if I look hard enough.

I note he also has two shackles and a swivel, so he gets the prize for the most complicated setup.

I think the jury is still out on whether the slot is of any benefit. Sure, you can raise a fouled anchor, if you are skilled in the operation of that type of slot, but can't you also trip an otherwise well secured anchor accidentally, just by drifting to around 180 degrees and pulling gently?
I'll stick to a short slot and one shackle for my system, thanks.

"just by drifting to around 180 degrees"

As in when the current reverses OR when you are about to get whacked by a T storm?

The slot is for tripping a fouled or heavily embedded anchor, and does it very well, with no extra floaty contraptions needed to complicate things, merely by taking up nearly all the slack and while chain is vertical motoring slowly forwards over it. Not to mention the fact most never think to set their anchor trip line & buoy up until they are fouled, by which time, about all you can say is....bugger...I should have rigged my anchor trip line and float, but I thought the bottom here would be ok.
As to the theoretical loss of set of the anchor....yawn...an endlessly repeated mantra by those who don't have an anchor with this system, but in my experience, never encountered in real life, as in real life the anchor chain never traverses an exact straight line back over the anchor shank, (and even in the freakish situation it did it would set again in no time), so it just pulls the end of the shank around as the boat reverses direction with tide or current just like every other anchor, perhaps momentarily disturbing the set a tad, but it beds in that damn quick again, it's irreverent....yawn.* See for yourselves, don't take my word for it....
http://www.anchorright.com.au/products/sarca-anchors


-- Edited by Peter B on Sunday 23rd of January 2011 06:14:50 AM

I just came back from the boat and see that my Manson Supreme has a slotted hole below the long slot. What I may do is bolt a 12lb split round of lead on the end of the shank to boost short scope performance. I think if I regularly used a trip line I'd have to have two lines*** ...one about 50' and one about 90'. I've only deployed a trip line once but it didn't seem like much trouble. Our big tides here don't help. Peter, I still don't know any source for those Sarca anchors in the US.

nomadwilly wrote:

I've only deployed a trip line once but it didn't seem like much trouble

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We use a trip line with our anchor fairly often (we did with the Bruce, too).* We've never had a fouling problem with it at all.

PeterB--- All the posts and comments in magazines about the problem of the "trip slot" in the* Manson Supreme were from people who had the anchor and had it un-set when the wind or current moved the boat out to the side or around behind it.* The comments weren't from people speculating on what might happen, they were from people who had it happen.*

Perhaps the Sarca's geometry is such that this is not a problem with that anchor.* All the accounts I've read were from Manson owners.* I've never seen anyone comment on this problem or non-problem in reference to a Sarca.

*

Marin, Peter B,
Very few anchors don't break out in a 180 degree turnabout. And those that don't break out probably only not do so in certain bottoms. So basically if you do a 180 your going to break out so what's the difference if you break out w or w/o the slot?

"We use a trip line with our anchor fairly often"
On what occasions do you not use the trip line?

I agree with the 180 degree bit. The thing that turned me off this whole "trip slot" thing were the comments that when the boat gets off at 90 degrees or so, this is when the shackle can start sliding down to the fluke end. And when it gets there it doesn't take much pull to un-set the anchor. The people relating these experiences felt that had the rode been attached to the shank in the conventional manner, it would have taken a lot more pull to haul the anchor out of the bottom. But once the shackle slid down to the fluke end it took relatively little pull (they said) to un-set it.

We don't use a trip line if we know or read that the bottom is free of things like logging cables, chains, sunken logs and whatnot. Our basic rule is that if we know or read/hear that the bottom in an anchorage has a reputation for having debris, or if it's a new anchorage to us and we have no definitive information one way or the other, we use the trip line.

Morning Marin,
Maybe but maybe not. The shank will have a great deal more leverage applied to it w the rode attached to the end of the shank as opposed to the middle. Should be levered out more easily when attached to the end I would think. However, the rode attached to the middle of the shank is closer to the flukes and THAT may pull it out where as attached to the end may just rotate the buried anchor??? Too much swimming to find out.

"The people relating these experiences felt that" Yea people feel all kinds of things.
Consider all the wild things I've "felt" in the past. But I'm not criticizing your saying they felt this or that as all things should be considered but much should be taken w a grain of salt.
I think I should be using the trip line all the time. Are you not using the trip line based on what people "felt" was down there? There are places like Echo Bay where so many boats anchor so much of the time one could assume***** .....but ask Paul Graff about assuming.



-- Edited by nomadwilly on Monday 24th of January 2011 10:50:00 AM

Who uses a trip line with an all chain rode, 60 - 100 # anchors and where/when?

nomadwilly wrote:

1. The shank will have a great deal more leverage applied to it w the rode attached to the end of the shank as opposed to the middle.

2. Are you not using the trip line based on what people "felt" was down there?

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1. Whenever the direction of pull is not countered by the maximum fluke resistance, the possibiity of the anchor coming out goes up.* When the shackle holding the rode slides down to the fluke end of the shank, regardless of whatever leverage there may be the pull is now being applied at an angle with greatly reduced resistance from the fluke or even the least resistance from the fluke.

2. We go on what other boaters have experienced or know regarding the nature of the bottom.* If it's a new anchorage to us and we can't get any firsthand information as to the nature of the bottom, we'll use the trip line. We're not too interested in what someone might "feel" is down there, but we are interested in what they may know is down there.* If nobody knows, we'll use the line.

Marin, you are right, the Sarca and the Manson Supreme are indeed different, in fact the elongated slot and the roll-bar is the only similarity. Do you have any links to these stories of Mansons un-setting with the slot in use? I am genuinely intrigued to get to the bottom of this. The fact that the only time one would be concerned re an un-set being when the wind and/or current get up, and in this scenario, the probability of the shackle slowly wandering down the shank towards the fluke seems most unlikely because of the tension which would be on it keeping it at the end of the shank. I have certainly never heard of a Sarca doing this. The one explanation I can think of for the different performance is the fact that the Manson has a concave, as opposed to more traditional convex fluke shape. Sarca experimented with the concave, but found it did not really enhance holding, but did gouge huge chunks of seabed up, and maybe it is this large wedge of material held in the dislodged fluke which causes it to not re-set properly, which is presumably what these folk have complained of. Otherwise, these roll-over anchors re-set so quickly, they would normally not even notice it had happened. The Sarca fluke, being convex shaped, not too different from the old plough, just turns round in the bottom subtrate without breaking out, or if it did break out, would re-set almost immediately as result of its sharp tip, and with no chunk of bottom filling the fluke. Does that theory sound reasonable to you?

Peter B wrote:Do you have any links to these stories of Mansons un-setting with the slot in use?

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Unfortunately most of them were on the T&T list, which has about the most user-unfriendly search function on the planet.

I don't know enough about the differences between the Manson and Sarca designs to speculate on whether the Sarca is more resistant to this movement of the shackle down the slot when the boat is moved out to the side by the wind or current.* The only comments I have seen about this were with regards to the Manson.

There have been a few boats with Mansons in our part of the marina, most recently a new Ranger 29, *and I've*noticed that they--- and all the boats I've ever seen pictured with a Manson in magazines and whatnot--- have the rode*shackled to the*hole in the end of the shank, not the slot.

The slot is a clever idea, no question.* It's too bad the designer didn't figure out a foolproof way of letting the shackle slide down the slot to the fluke end only*when you wanted it to.

I use the slot but I put a bolt through the slot to keep the attach point at the far end just above the regular hole. I feel the slightly elevated position of the shackle may help short scope performance. But until the wind was really scream'in* 2 or 300' of of chain would do more for short scope performance. I've only used the Manson Supreme several times and aren't thrilled w it judging how it sets. What do the experts on your float say about it Marin?
All the anchor pics I've seen that I can recall illustrate the shackle being attached w the shackle pin inserted through the hole in the shank. If Rick's explanation is correct one would think pictures of anchors would show shackles being installed the correct way, that is w the pin through the chain link and the closed end of the shackle through the small slot in the shank.

PS,
Peter,** your'e boat looks bigger from the stern but better from the bow.





-- Edited by nomadwilly on Tuesday 25th of January 2011 11:10:08 PM

Anybody using this to save their anchor and rode?

http://www.anchorsaver.com/Anchor_Saver/Home.html

Mark,
So if the shear bolt was for a 50' boat my little 37hp Willy would never be able to shear the bolt and I'd still loose my anchor.

Eric, they have several models, and selection*depends on anchor type and boat size.* I assume the manufacturer would say they have the right model for you and*"Little" Willy.

http://www.anchorsaver.com/Anchor_Saver/PS_Claw_Anchors.html