Photos of Anchors Setting

[noelex 77]

Another Delta.

This one was set at only set at 3:1 in 7m and was not coping very well at all at this short scope.

While setting under engine it had dragged about 7m. The engine was cut and the anchor started dragging in a new direction corresponding to the wind force. You can see the kink in the long drag mark. It showed no signs of setting deeper.

I suspect the skipper had no idea his anchor was slowly dragging with each gust. Fortunately they left late afternoon.

[Factor]

Originally Posted by Pete7

the Rocna had a ball of mud on it which took quite a bit of dunking to remove.

This has always been my concern with sugar scoop anchors. If they come out as a ball of mud, they have little chance of resetting. Ever. Maybe its why the first two roll bar anchors weren't scoops.

[Palarran]

Originally Posted by Factor

This has always been my concern with sugar scoop anchors. If they come out as a ball of mud, they have little chance of resetting. Ever. Maybe its why the first two roll bar anchors weren't scoops.

I had that same concern but as some of the photo's on this thread have shown, the anchors rotate without pulling out so it's less now. Also, while I've had some big balls of mud/weed stuck on the anchor, the tip has always been clear so I'd hope it would bite again and the stuck weed would be pushed out/off the anchor.

Has anyone ever had it happen where a new generation anchor with a roll bar pulled out due to a wind shift or tide and didn't reset due to a weed/mud ball?

[poiu]

Originally Posted by Llamedos

...The biggest impact on the scope required is actually the weight of the chain and the catenary effect of that weight...

... Obviously a yacht in windy conditions can exert much more force on the chain than you can but it will still not be able to actually straighten the chain in anything but the most extreme conditions...

Sorry for contributing to what might be thread drift.

I disagree with the first point. If you set your scope to achieve a desired angle of pull on the anchor and make that choice to allow for storm conditions then catenary has no effect on scope as the chain is nearly straight. The biggest impacts on scope required are the strength of holding, , the holding power of your anchor, the strength of wind expected and how much scope you are able to let out. I would agree with what you say about catenary if it were to relate to low wind strengths up to say 20kt where the catenary has a big effect on the pull angle on the anchor.

As to the second point. The chain can never be straightened out. It will break before it flattens. At somewhere around a quarter of the chain's breaking strength the flattening of the catenary is at the upper end of the exponential reduction of the curve. From there to the chain's breaking point is a matter of a few inches in a typical scenario. The chain at that stress will have more elongation (and damping effect) from its elasticity than from the catenary curve elongation.

[colemj]

Originally Posted by Palarran

Has anyone ever had it happen where a new generation anchor with a roll bar pulled out due to a wind shift or tide and didn't reset due to a weed/mud ball?

Yes - weeds.

Mark

[Palarran]

Originally Posted by colemj

Yes - weeds.

Mark

How far did you let it drag before you retrieved it and cleared the weeds?

I hate weeds

[Panope]

45 lb Manson Supreme. 7 ton Boat. 4 to 1 scope. Sub-strait sandy mud with some small gravel. I belay the chain with a chain hook shackled to a heavy tang that is welded to the deck - not much stretch. Set using boat inertia (about 2 knots in reverse).

Set happened very abruptly (warn passengers before coming to end of chain). Anchor is upright. Fluke completely buried with no "piling". Shank is mostly burried (slot just visible in photo). Weed (dark material in photo) not a factor as anchor was dropped just clear of weed patch.

Water temp = 53 degrees Fahrenheit. Sorry for the crappy photos.

Steve

[chasfgr]

Originally Posted by noelex 77

Thanks for the comments Charlie.
There have been a few calls for this so I will try and get around to it, but no promises.

I always watch the anchor land on the bottom if possible (and it usually is possible in this clear water). If you free fall it down, it lands with a satisfying puff of sand like a mini mushroom cloud .

Anyway on every occasion I have observed it, the Mantus has landed upright (not even on its side). It seems to naturally fall this way. However, it is very hard to know if different sized chain, or even a big swivel or removing the rollbar would alter the "flight characteristics" due to a different balance point or hydrodynamic drag.
I doubt it, but it is impossible to test all the combinations.

Slowly lowering the anchor obviously does not produce the same result. Although if traveling backwards (as you should do) it should also land upright but perhaps not with the consistency of the drop method.

If the anchor is dropped the risk of it landing upside down seems small at least in my configuration. This does not answer the question, but that's all I can offer at the moment.

The Mantus on-line brochure definitely suggests you can dispense with the anti-roll bar. In fact I'd suggest it will lower the CofG and increase the likelihood of landing flukes down.

http://mantusanchors.com/wp-content/...BookletPDF.pdf

[Sulaire]

Yep just looked at the brochure. Thanks.

I am up for one , But as we will not be in a marina until november AND that marina will be in Turkey, not sure of how the logistics would work. Seems like the delivery charge will be huge and not to mention the lovely folks at the turkish import offices who love adding taxes!!

Oh well , nothing comes easy!

C.


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[chasfgr]

Originally Posted by Sulaire

Yep just looked at the brochure. Thanks.

I am up for one , But as we will not be in a marina until november AND that marina will be in Turkey, not sure of how the logistics would work. Seems like the delivery charge will be huge and not to mention the lovely folks at the turkish import offices who love adding taxes!!

Oh well , nothing comes easy!

C.


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If in Turkey look @ the Ultra - Noelex has some shots and it's performance is creditable - above all it's pretty.

[Sulaire]

Hi

Thanks , but i already have an ultra and yes it is pretty and works great. I am in the market for a second all rounder for the bow, and mantus seems to do the trick!

I could of course get a second ultra , but my wallet is still recovering from the first one!

C.


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[chasfgr]

Originally Posted by Llamedos

I have just found this thread and have looked through it with great interest, so firstly many thanks to Noelex and the other contributors for some very informative photos and observations.


However there has been some mention and discussion on anchoring scope and the factors involved, even though everyone has different ways of determining their ideal scope ratio. So perhaps a little more scientific explanation and discussion may be of benefit.


I have no problem with the concept of high scope ratios, 8:1 or even 12:1, in extreme conditions or deserted anchorages if that is your preference, after all chain does no good in the locker.


We are currently sailing in the same Greek Islands and Turkish Coast as Noelex and NornaByron so are very familiar with the depths and bottom conditions. (Never met Noelex but have shared a few beers with NornaByron) We anchor our 42ft, 15 tonne cat every night in the summer and have done for nearly 5 years so quite a bit of anchoring experience I think!!


In the Greek Islands and the adjacent Turkish Coast the anchorages are generally fairly crowded and many are quite small, this means that long anchor scopes are rarely possible and could probably be considered a bit selfish since you effectively take up more room if everyone else is on lesser scope ratios, and problems will almost inevitably occur if the wind shifts appreciably. Consequently scope ratios of between 3:1 and 5:1 are normal in depths of 4 to 10m of water, longer scopes would be almost impossible in many places.


The biggest impact on the scope required is actually the weight of the chain and the catenary effect of that weight – basically a length of chain will always have a curve in it (catenary) unless you apply huge forces to it (or it is vertical!!). This curve means that the angle of pull on the anchor shank will almost always be less than the angle calculated from the actual scope.


Try this experiment to see how big this effect is: lay out a 6m length of chain along your deck or on the dock and secure one end to a cleat, take the other end and raise it to chest height, this is about 4:1 scope, try and pull the chain absolutely straight. You will find it just about impossible to achieve, there will always be some small amount of curve in the chain due to the catenary effect. If you like you can try with 12m of chain and see how much bigger the curve becomes, hence as the chain length increases the catenary effect becomes more important so the end of the chain attached to the anchor is at a much lesser angle than you might expect, in fact it will likely to be almost lying on the sea bed in almost all conditions – and this is the angle of pull that is being applied to your anchor shank, not the predicted angle. Obviously a yacht in windy conditions can exert much more force on the chain than you can but it will still not be able to actually straighten the chain in anything but the most extreme conditions.


Just for completeness here are the predicted angles between chain and sea bed, at 2:1 scope the angle is 30 degrees, at 3:1 the angle is 19 degrees, at 4:1 it is 14 degrees and 5:1 gives 12 degrees. You should be able to see quite clearly that the improvement as scope increases becomes less and less so higher scope ratios are really of little benefit normally.


As already mentioned in previous posts the modern generation of anchors are designed to function correctly on lower scope ratios, Noelex has already reported good performance with his Mantus on 2:1 and 3:1 scopes. Personally I like to use a 4:1 scope in “normal” depths and have found this to work extremely well with our Rocna style anchor. I would go as far as to suggest to everyone that for “normal” conditions and depths with a modern anchor you will be perfectly secure with a 4:1 scope, longer scope will not increase your security very much at all.


So now to the actual effect of catenary as depth of water increases, most people probably know that you may not need your 4:1 scope of chain in deeper water say 15m deep but how much shorter can you actually go?


First we need a starting point and that is the depth of water at which you are happy to anchor with 4:1 scope. For us that is 4.5m of water, plus 1.5m water to bow roller giving 6m total and hence 24m of chain. Our experience shows that this works very well for winds up to 25knts maybe 30knt gusts and minimal wave action. As I said at the beginning by all means put out more in extreme conditions. At this scope ratio our anchor sets very quickly, digs in deeply and holds extremely well when anchoring on the type of sandy bottom shown in most of Noelex’s photos.


So what happens as the depths increase? The catenary effect of the chain becomes more pronounced and has more effect so you need much less scope than you imagine. The following figures are for 10mm or 3/8” chain and the calculations are fairly straightforward engineering formulae so they are accurate figures not guesswork.


Our starting point then is 6m overall depth (water + roller height) and 24m of chain, the calculations show that for 10m depth you now need 30m of chain (3:1) but the catenary effect of the chain means that it works exactly the same as your 4:1 scope at 6m depth. For 15m depth the chain length required is 38m and at 20m you need 45m to give the same effect as 4:1 scope at 6m. The calcs also show that you need more chain in shallower water so 4m depth will need 19m or nearly 5:1.


The calcs can also be used to show how much extra chain you need to increase your safety by a factor of 3, so at 6m depth you need an extra 6m of chain and at 10m you need an extra 7m to effectively give you an extra factor of safety of 3. This means you should be secure in much stronger winds and/or bigger waves, probably up to 45/50 knts and choppy waves.


Hopefully if you have managed to follow the details this far you can see that you actually need much less chain than you probably thought to anchor safely and securely. The catenary effect is a huge factor and reduces the angle of pull on your anchor. Next time you are anchored, preferably with 4:1 scope in 6m of water, go for a swim when you have a good strong breeze blowing or even better some stronger gusts blowing and observe the action of the chain close to the anchor – you should be able to see that even very big gusts hardly lift the chain off the seabed close to the anchor. It is very informative to actually have a good look at this.


I hope that this helps to demystify the effect of anchor chain scope on anchor performance and the effect of deeper water. Obviously the above discussion only applies to all chain rode and smaller chain size will have a lesser effect, thicker chain will have a bigger effect. Rope rode makes hardly any difference so stick to all chain if you can.


In conclusion I believe a modern anchor will perform as designed with 4:1 scope in 6m of water and longer scopes make little difference to holding power in “normal” anchoring conditions and good holding on the sea bed. Poor holding is a different matter entirely and Noelex has already said that an oversize anchor can give acceptable (maybe marginal) performance in poor holding conditions or you just have to hunt around for some better holding.

Many years ago Alain Fraysse did a spreadsheet for all chain and chain-textile rode combinations
http://alain.fraysse.free.fr
I occasionally refer to it, but based upon a 6:1 scope, 25 knots of wind and my boat's characteristics, his spreadsheet gives a minimum 7kg anchor on the end of 25m chain and 10m nylon rode and a 6 degree incidence.
The significant variance is in gusts, when the dynamic overtension with textile/chain will be 172 daN whereas with the same length chain-only rode the maximum would be 390 daN.
Here less is better.
He also rates the "new-age" anchors as 30% more efficient than CQR/Brittany/Delta/Bruce/Danforth.
I downloaded the spreadsheet in October 2006, but people may find his theory and the calculations of interest.

[chasfgr]

Originally Posted by Sulaire

Hi

Thanks , but i already have an ultra and yes it is pretty and works great. I am in the market for a second all rounder for the bow, and mantus seems to do the trick!

I could of course get a second ultra , but my wallet is still recovering from the first one!

C.


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Many would opine that, as different bottoms suit different anchors, one's second bower should be a totally different design.
Don't give up hope - I've costed a 25lb Mantus to Greece and including probable VAT and Excise costs it's still under US$400.

[colemj]

Originally Posted by Palarran

How far did you let it drag before you retrieved it and cleared the weeds?

I hate weeds

Either zero or infinity, depending on how you look at it. We were anchored in muddy water and thought we had a good hold (backed down hard, etc) for a couple of days. A sudden squall came through with 50kt winds and bingo - we were on the move at a high rate of speed. The anchor came up with a giant ball of weeds on it - probably 5' diameter and 200lbs.

We circled around until I could pull all the weeds off it and reanchored in less weedy place.

One thing was clear, the anchor (Rocna) dug down into the weeds and held fine for a couple days of normal 15-20kt winds. However, with those types of weeds, I think the root systems go further down than the anchor can dig and don't provide sure grip.

Mark

[noelex 77]

This was another Delta. This one has not had any force put on it. There is no drag mark and the toe has only just engaged, but this is not fault of the anchor it had just been dropped and left on the bottom.

People have asked what an anchor looks like that is just dropped on the bottom and this is it. Of course it is impossible to speculate how the anchor will perform at this stage.