Anchor choices

[Dockhead]

Originally Posted by kmacdonald

The problem I've had is the anchors not resetting in a wind shift. Most anchors set well when clean of mud. When the they are covered in mud or clay the weight distribution changes and they dont reset well. Size wont help with that. Nothing will.

Try a bigger anchor. Size WILL help with that. A bigger anchor will sink down deeper.



Also, soft mud clogs roll bars and will lead to this problem. You might try a non-roll bar anchor like Spade, Ultra, Rocna Vulcan, etc.

[Mike OReilly]

Originally Posted by kmacdonald

The problem I've had is the anchors not resetting in a wind shift. Most anchors set well when clean of mud. When the they are covered in mud or clay the weight distribution changes and they dont reset well. Size wont help with that. Nothing will.

Design matters. Size is an aspect of design. Bigger will almost always be better.

It's not that the weight distribution changes. It's that the flukes get fouled so cannot penetrate as easily. Danforth-style respond the worst. CQRs also struggle to reset more so than the newer style anchors.

Uncontrolled resetting is a crap shoot, which is why the best solution is to not get into that situation. A properly set and dug-in anchor doesn't easily come out in a wind shift. When force directions shifts due to wind or current a properly dug-in anchor will tend to crab around, but won't easily disengage from the substrate. Again, newer-style anchors are better designed, and bigger is better (assuming the anchor is set and dug in).

Of course, any anchor can get pulled out given the right conditions. A direct and rapid 180º shift is the most dangerous situations. But here again, anchor tests and research like Panope's show that the newer scoop-style anchors reset better than older designs.

[noelex 77]

Originally Posted by kmacdonald

The problem I've had is the anchors not resetting in a wind shift. Most anchors set well when clean of mud. When the they are covered in mud or clay the weight distribution changes and they dont reset well. Size wont help with that. Nothing will.

A good anchor should “shuffle” in response to a change in wind direction. This means the anchor stays buried and engaged with the seabed.

However, anchors do develop a list and at least slightly less grip as they rotate. If an anchor does not have enough grip for the conditions, substrate type and boat size, this is when it is most likely to break out.

An anchor moving at any speed finds it difficult to engage with the seabed and will collect substrate and debris on the fluke. The trick is to avoid the break out in the first place.

So an anchor dragging with a wind shift is often an indication that the anchor had only marginal grip in a straight line pull and therefore broke out while rotating. A larger anchor will definitely help in this situation, as will an anchor that “shuffles” better and retains a higher percentage of its straight line holding power.

You have been a strong proponent encouraging limiting the size of your anchor. I understand the reasons behind this, but the consequences of this compromise is that in conditions where the grip of your anchor is marginal, it is most likely to break out while rotating so your experiences are not surprising.

[Lodesman]

Originally Posted by noelex 77

So an anchor dragging with a wind shift is often an indication that the anchor had only marginal grip in a straight line pull and therefore broke out while rotating. A larger anchor will definitely help in this situation, as will an anchor that “shuffles” better and retains a higher percentage of its straight line holding power.

You have been a strong proponent encouraging limiting the size of your anchor. I understand the reasons behind this, but the consequences of this compromise is that in conditions where the grip of your anchor is marginal, it is most likely to break out while rotating so your experiences are not surprising.

Wouldn't you say that an anchor that is well dug-in will perform better in a shift, than one that isn't well dug-in? If this is the case, then presumably an anchor could be "too large" if you lack the horsepower to set it deeply.

[Dockhead]

Originally Posted by Lodesman

Wouldn't you say that an anchor that is well dug-in will perform better in a shift, than one that isn't well dug-in? If this is the case, then presumably an anchor could be "too large" if you lack the horsepower to set it deeply.

Sounds good in theory, and I bet there is SOME size where you will start to have trouble setting it, but I think that size is a lot bigger than what we can fit on the bow. I had a 121 pound Rocna for a while and no trouble whatsoever setting it even at low power settings. In fact it even seemed to set it self in many bottom types. I set my anchor with a long pull at low RPM. Then test the hold by winding up to redline.

Based on that, I feel certain that even a 240 pound anchor would not be a problem setting -- no power limitation on it. Carrying it on the bow is another matter of course.

In my experience there are two things which affect this -- how sharp the fluke is, and how big the anchor is. The more of either of these, and the deeper and better the anchor will set.

[hpeer]

Attached (hopefully) is the Mantus recommendations.

I have a 44’, 40,000 pound boat. It has a 5’ bowsprit so I’m 49’ LOA.

I have personally experience 50 knots wind speed while coming into anchor. These were gusts, not sustained. Little fetch so small waves. Subsequently I’ve seen 60 knot gusts in the same spot. At that point some of the pontoons were experiencing damage due to wind load on big motor cruiser.

I had a recommended size 66# Spade and I didn’t think that adequate. I was able to make a sheltered pontoon thankfully.

When I went looking for an anchor I had that experience in mind.

I looked at the chart, talked to the Mantus rep and thought, I’ve experience 50 knots, I want some extra over that. Thus I went up one more step.

I get all the arguments about setting and doing it right etc. There are times when “Stuff happens” and you drop and pray, don’t worry about backing down, the wind will get ‘er done for ya. It’s 2am, your on the end of a 36 hour solo passage, it’s blowing and your cold. At those times you don’t want to worry about style, you want the anchor to STICK! Period.

Bottom line; don’t buy the anchor that should work. Buy the anchor that WILL work when you don’t, when you’ve made a mistake.

Now I’m talking cruising in interesting areas. Not so much within the Chesapeake. Day sailors, weekenders, in known waters with mud bottoms...that’s different.

[noelex 77]

Originally Posted by Lodesman

Wouldn't you say that an anchor that is well dug-in will perform better in a shift, than one that isn't well dug-in? If this is the case, then presumably an anchor could be "too large" if you lack the horsepower to set it deeply.

We have used considerably oversized anchors and this has never been a practical problem.

I have never seen either our Rocna or Mantus anchors do anything other than “shuffle”. This is in 12 years of anchoring averaging over 300 days a year. Until recently, on most of these occasions the anchor performance has been visually checked. The marks in the substrate show quite clearly if the anchor has broken out and reset or simply “shuffled” (ie stayed engaged with the seabed and rotated without otherwise moving).

I suspect an oversized anchor helps the shuffling process because the anchor has a high mass and large fluke area, which slows down and hinders the rotational movement. This also gives the substrate longer to consolidate, preventing the “liquefaction” and loss of grip associated with rapid movement.

However, if you have a good primary anchor set in a reasonable substrate and the anchor is not near its limits of ultimate grip, the risk of the anchor breaking out completely is very slight irrespective of the anchor size.

If the anchor has marginal grip in the first place (perhaps because of the substrate, conditions or anchor size), or has a design that develops a very high list and poor engagement during the rotation, then the risk of it breaking out during the rotation increases. If the anchor does break out it can sometimes reset, but a rapidly moving anchor finds it very hard to develop enough grip.

The anchor will pick up debris and substrate on the fluke, as it drags and this is sometimes blamed as the cause of dragging when often it should be more correctly interpreted as a consequence of the dragging.

[Dockhead]

Originally Posted by noelex 77

However, if you have a good primary anchor set in a reasonable substrate and the anchor is not near its limits of ultimate grip, the risk of the anchor breaking out completely is very slight . . .

This "not near its limits of ultimate grip" is worth underlining.


You can't write a table and say that such and such an anchor is categorically adequate for a given size boat. That's because the bottom type, and scope, apply a rather huge coefficient to whatever the theoretical max holding power of any anchor is. Trying to remember Alain's table, I seem to remember that the difference between holding power between excellent and poor bottom in his table was something like 10x. And in reality I'm sure it's even more than that.


So an anchor which is perfectly adequate on good scope in a good bottom may fall way short in a poor bottom and/or short scope, whereas a bigger one might not.


It's this huge practical variation between good and poor bottoms, and other circumstances, which is why there is no such thing as too much anchor, provided you can still handle it.


I had to ride out a gale in Greenland on scope of 2.5:1 -- because I couldn't find any bottom I could get my hook into in less than 40 meters of water. If we had dragged, I wouldn't have been able to head back out, because the sound was full of ice. I was awfully glad that day that I had not followed the maker's recommendation on anchor size. I shudder to think what would have happened if we had dragged, but we didn't.

[Lodesman]

Originally Posted by noelex 77

We have used considerably oversized anchors and this has never been a practical problem.

I wonder where the cut-off point is? I don't suppose anyone has ever put it to a test wink wink...

[Panope]

Originally Posted by Mike OReilly

Design matters. Size is an aspect of design. Bigger will almost always be better.

It's not that the weight distribution changes. It's that the flukes get fouled so cannot penetrate as easily. Danforth-style respond the worst. CQRs also struggle to reset more so than the newer style anchors.

Uncontrolled resetting is a crap shoot, which is why the best solution is to not get into that situation. A properly set and dug-in anchor doesn't easily come out in a wind shift. When force directions shifts due to wind or current a properly dug-in anchor will tend to crab around, but won't easily disengage from the substrate. Again, newer-style anchors are better designed, and bigger is better (assuming the anchor is set and dug in).

Of course, any anchor can get pulled out given the right conditions. A direct and rapid 180º shift is the most dangerous situations. But here again, anchor tests and research like Panope's show that the newer scoop-style anchors reset better than older designs.

Howdy, Mike

I appreciate and agree with almost all of your very thoughtful posts on anchoring and most other topics here on CF.

However, I must comment your statement above (in bold).

If "reset better" = ability to rotate and stay engaged during rotation, then the statement has some accuracy. For example, the (45lb) Mantus M1 anchor has perhaps the strongest tendency to rotate and remain engaged of any anchor that I have tested.

If "reset better" = ability to re-engage the seabed after becoming dis-engaged, then the statement is false. With the exception of the 45 CQR (copy), ALL of the steel convex anchors that I have tested (Delta, Excel, S. Sarca) re-engaged 100% of the time with no evidence of fouling, while some concave (scoop) anchors (Manson Supreme, Rocna, and 13 lb Mantus) had problems with re-engagement due to fouling.

I would love to be able to make sweeping, generalized, statements about anchors (convex does this, concave does that, modern does this, roll bars do that, weighted tips do this, etc). However, my testing increasingly teaches me that these generalized statements are fraught with great peril.

Most recently I have become interested with the effects of anchor SCALE (does a smaller version of an anchor behave the same has larger?). This research is just getting started, but it appears that scale factor might be significant enough that we should not even make generalizations about a particular anchor BRAND (Bruce anchors do_____) without stating the size also.

Steve

[Dockhead]

Originally Posted by Lodesman

I wonder where the cut-off point is? I don't suppose anyone has ever put it to a test wink wink...

It's apparently bigger than this:






https://setsail.com/anchoring-system...ch/#more-46615



Dashew says:


"So, how big an anchor is right?

"This is a tough calculation. Typical tables published by anchor suppliers or organizations like NMMA are a joke. They assume good holding, and moderate, protected anchorages. Our basic rule has been to use a multiple of what would be considered a storm anchor."

SetSail FPB » Blog Archive » How Big Should Your Anchor Be?

[Mike OReilly]

Originally Posted by Panope

Howdy, Mike

I appreciate and agree with almost all of your very thoughtful posts on anchoring and most other topics here on CF.

However, I must comment your statement above (in bold).

If "reset better" = ability to rotate and stay engaged during rotation, then the statement has some accuracy. For example, the (45lb) Mantus M1 anchor has perhaps the strongest tendency to rotate and remain engaged of any anchor that I have tested.

If "reset better" = ability to re-engage the seabed after becoming dis-engaged, then the statement is false. With the exception of the 45 CQR (copy), ALL of the steel convex anchors that I have tested (Delta, Excel, S. Sarca) re-engaged 100% of the time with no evidence of fouling, while some concave (scoop) anchors (Manson Supreme, Rocna, and 13 lb Mantus) had problems with re-engagement due to fouling.

I would love to be able to make sweeping, generalized, statements about anchors (convex does this, concave does that, modern does this, roll bars do that, weighted tips do this, etc). However, my testing increasingly teaches me that these generalized statements are fraught with great peril.

Most recently I have became interested with the effects of anchor SCALE (does a smaler version of an anchor behave the same has larger?). This research is just getting started, but it appears that scale factor might be significant enough that we should not even make generalizations about a particular anchor BRAND (Bruce anchors do_____) without stating the size also.

Steve

Thanks Steve, and I'm sorry for mischaracterizating or oversimplifying your findings. I was just reviewing your videos and was about to amend my comments, but you've done a far better job.

My apologies .

[noelex 77]

Originally Posted by Lodesman

I wonder where the cut-off point is? I don't suppose anyone has ever put it to a test wink wink...

I think it is unlikely that there is a cut off where anchor size becomes large enough that the performance starts to deteriorate.

Despite the primitive design I would be comfortable tying up my boat in poor conditions to the large sized anchor pictured below. Obviously I could not deploy or manage such an anchor.

It is an extreme example of an oversized anchor to illustrate a point, but while this so large it is not remotely practical, I would not be concerned about the holding power.

[Lost Horizons]

Originally Posted by Dockhead

No one ever lay in his bunk at night at anchor with a gale howling thinking "I wish I had a smaller anchor".

.

However, that is exactly what they are saying the morning after when their windlass cannot dig up the anchor buried deep in a mud (and there is not a ripple of swell to help).

[Dockhead]

Originally Posted by Lost Horizons

However, that is exactly what they are saying the morning after when their windlass cannot dig up the anchor buried deep in a mud (and there is not a ripple of swell to help).

A person in that position needs anchoring lessons, not a smaller anchor.


You don't pull the anchor out of the seabed with the windlass, whether it's big or small.