Anchor choices

[Panope]

Originally Posted by Dockhead

Have you noticed smaller anchors burying better than larger anchors of the same type?

If "burying better" means burying with less force, then yes, I have noticed smaller anchors burying "better"

If "burying better" means ability to bury ITSELF (to the point where it disappears) regardless of pull strength, then no, I have not noticed a small anchor burying better.

If "burying better" means ability to bury to a deeper ABSOLUTE DEPTH, then no I have not noticed a small anchor burying better.

Steve

[kmacdonald]

Originally Posted by Dockhead

It is perhaps not surprising given the plow-shape of the Delta, that the Delta is very good at plowing up the bottom.



We loved our Deltas when they first came out because they were at least better than our hated CQRs. But it was only a modest improvement over an awful precedent.


I've had three different Deltas of different sizes. The last one was a 25kg which I inherited from the PO of my present boat. It worked somewhat better than the smaller ones, but still crap compared to any new gen anchor. I gave it away; couldn't in good conscience take money from anyone for it.



I wouldn't waste my time with that anchor, if I were you.

Yes, I replaced it with a Manson supreme. It dragged in the soft muck and silt but not nearly as bad as the Delta. I use a anchor alarm and sleep fine. The Chesapeake mud doesn't present a problem even when you do drag or run aground. In the southern Chesapeake there is a lot of sandy bottom and when the Fortress is set to the low angle it holds great and usually resets. The new gens always work great in the sand.

[Lodesman]

Originally Posted by Panope

If "burying better" means burying with less force, then yes, I have noticed smaller anchors burying "better"

This, or rather the corollary that for a given pulling force, the smaller anchor buries a greater percentage of its volume, than a larger anchor.

[evm1024]

Originally Posted by Lodesman

This, or rather the corollary that for a given pulling force, the smaller anchor buries a greater percentage of its volume, than a larger anchor.

Provided the pulling force does not cause a failure of substrate cohesion.

[Simi 60]

We never back down on our 150lb manson supreme anymore - did it the first time we used it and thought we were going to break something.

Instead we just let wind, current, weight of vessel do the set.
When dived on more often than not it is just the top of the shank and some hoop that is visible.

[Panope]

Here is the new test that I mentioned earlier. This 17lb. Excel performed nearly as well as it's larger version (47lb.).

https://www.youtube.com/watch?v=52r4-PhTM9k

[noelex 77]

Originally Posted by Dockhead

OK, well, I said it in the form of a question. Here's the answer!
I'm still skeptical, but here's another voice, another one we all respect, and a well-reasoned argument.
Now I'm even more curious to hear whether Noelex has observed any such effect. Or Steve.
If it really does work like that, could it be specific to Fortresses?

I do not trust my Fortress anchor in conditions where there is the possibility of a significant change in the direction of pull.

When observing this anchor model underwater, while rotating it will sometimes develop a very high list as it rotates. Puzzlingly, it does not always develop this problem, but it is frequent enough to be concerning. Even from this position the anchor can often reset. If this happens the boat owner will not realise anything worying has occurred, but it is very disconcerting to watch this happening underwater.

As well as observing Fortress anchors deployed by other boats, I have spent many hours dragging around my very small Guardian anchor in shallow water (this is the slightly simplified version of the Fortress) in an effort to understand why this happens.

I certainly don’t have any definitive answers, but my best hypothesis is the problem is related to the change in resistance of the substrate with depth. As the Fortress rotates and develops a slight list (all anchors do this to some extent with rotation) the end of the very long stock is at a significant differnce in depth on the low and high side. If the substrate resistance is much higher on the low side, the stock effectivly trips up the anchor, causing the behaviour I have observed. I believe substrates that become significantly firmer with depth tend to produce the problem.

I have not seen any correlation with the depth of set, other than if the anchor is set so shallow that one side of the stock breaks out of the substrate, it exacerbates the the difference in resistance on the two ends of the stock.

In the correct substrate the Fortress has exceptional holding power in a straight line pull. On the other hand, in the wrong substrate or following a change in the direction of pull, the Fortress can have very poor or almost non existent holding.

So there is less value and therefore incentive to oversize the Fortress compared to other anchor designs. If the Fortress is working well, even a relatively small anchor can hold a large boat. On the other hand, if the Fortress is not working well even a large anchor (for the boat size) is likely to have such poor holding that the boat will still drag at a relatively low windspeed. Most anchor designs do not behave this way.

As most will know, I am convinced of the benefits of oversizing the anchor where this is feasible, but my Fortress anchor is not oversized. I think with this design of anchor oversizing will not help as much as is does with other anchor models.

In my view, avoid using a Fortress where there is risk of a significant change in direction of pull. On the other hand, it is a great kedge anchor. Every long distance cruising boat should strongly consider purchasing one for this purpose. (The cheaper Gardian is almost as good if on a budget). The unusual properties of the Fortress anchor itself and its intended use (as a kedge) mean there is less incentive to oversize this design of anchor.

So I think Dockhead is correct in suggesting Fortress is a special case:

Here is a photo from the many, many hours I have spent trying to understand why this problem occurs. It shows my small Guardian anchor that was broken out because of a change in direction of pull. Despite a very suitable substrate for this anchor, once broken out is quite stable in this position and will drag with minimal resistance showing no tendency to subsequently adopt the correct orientation. Oversizing the anchor when it is behaving in this way is of little help.


Please note the above are my personal views. Despite having owned a full sized Fortress for well a decade and spending many hours experimenting with a small Guardian anchor, I do not fully understand the behaviour of this design of anchor when subject to a change in direction of pull.

[noelex 77]

Originally Posted by kmacdonald

In my experience, the Fortress with mud paws and set to greater fluke angle doesn't set well in a hard bottom. Just thought I'd throw in another variable. I dragged my Delta around the Chesapeake so much that I could have farmed corn. It was on the large size according to my standards.

You cannot use the larger fluke angle (45°) of the Fortress in anything other than a very soft substrate.

In a hard bottom with the fluke angle set at 45° the anchor will not work at all. Always use the shallower 32° setting unless you are positive the substrate is soft, or very soft.

[Factor]

Originally Posted by Panope

Here is the new test that I mentioned earlier. This 17lb. Excel performed nearly as well as it's larger version (47lb.).

thanks Steve, Appreciate your reviews, that was amazing stuff for an 8 kilo anchor. Re your thrust pulls, to provide a comparison, a friend measured thrust pulls on his 10 metre sailing cat found that his engines developed around 200 lb of thrust each measured via load cell

[Dockhead]

Originally Posted by Lodesman

This, or rather the corollary that for a given pulling force, the smaller anchor buries a greater percentage of its volume, than a larger anchor.

That sounds reasonable, "for a given pulling force". But only if that "given pulling force" is less than what is required to fully bury the larger anchor. If it's more than that, then both anchors will be buried 100%.



So the big question is to what extent the actual available pulling force reaches that level, right? To what extent we are limited by available pulling force?



I would love to hear Nolex's observations -- did he see a lot of large anchors, not fully buried, suggesting that many boats can't develop enough pulling force to fully bury a larger anchor?


My guess is that with the realistic sizes of anchors we have, this is not an issue on normal cruising boats with normal diesel propulsion of average size.


Why? Well, because you don't see anyone setting anchors at full throttle, yet most anchors are well buried. I set all my anchors with RPM just above idle. If I can set a 121 pound Rocna with 1000 RPM, then I can be sure I will also be able to set a 200 pound Rocna without using all 100 horsepower, even if it takes more than 1000 RPM.



In theory there is some size of anchor you can't set with your available power, but for normal diesel cruising boats, I guess this is way bigger than any anchor we can fit. This may be very different for boats without engines, or boats with electric propulsion.



OK, but those are guesses. What sayeth those who have actual observations?

[Mike OReilly]

Originally Posted by Panope

Here is the new test that I mentioned earlier. This 17lb. Excel performed nearly as well as it's larger version (47lb.).

My initial reaction on first seeing an Excel anchor was that it looked at lot like the poorly performing Delta. But I've since learned how wrong I was.

When it comes time to replace my current bower (Rocna 25) I'll be looking hard at these Excels. So, thanks Steve (once again).

[hpeer]

Geeze guys. I don’t get this conversation about setting because the bottoms are so different. To make any significant testing you would need to have some kind of “standardized bottom.”

If you are in loose mud then pretty much the only thing that matters is the fluke area, you need to grab as much resistance as possible. OR you need something heavy enough or shaped right to bury into a deeper substrate. If you are in thick grass then you need sufficient weight on a sharp point to make the initial penetration and start digging or else it will just skid over. If you are in rocky bottom, busted coral I think you want as much weight as you can get.

I think there are times a roll bar can work against you. Such as in grass when it can plug, the Mantus roll bar seems to plug less? But also in rock, where ricks can jam into the roll bar keeping them from finding the bottom, whereas a non-roll bar anchor will move around rocks until it finds some bottom. I have picked up rocks in my roll bar and have seen other do it also. I’ve drug my 125# Mantus 100 yards in broken coral/rock in setting with no luck, only to make a second attempt and set hard right away. Was the roll bar jammed with rock the first try? I’ve seen a place where it is nothing but rock ledge with some grass. You drag the anchor around until you catch a piece of grass and hope to not pull it off the rock, only a settled weather anchorage that one.

It just strikes me that there are soooo many variables that one anchor may work better here and another there.

[ranger58sb]

Originally Posted by kmacdonald

Yes, I replaced it with a Manson supreme. It dragged in the soft muck and silt but not nearly as bad as the Delta. I use a anchor alarm and sleep fine. The Chesapeake mud doesn't present a problem even when you do drag or run aground. In the southern Chesapeake there is a lot of sandy bottom and when the Fortress is set to the low angle it holds great and usually resets. The new gens always work great in the sand.

FWIW, an adjustable SuperMAX and a Fortress has been our solutions to Chesapeake mud (slime, soup, muck, goop, etc.). Haven't even yet had to change the SuperMAX to the "mud angle" yet.

-Chris

[Mike OReilly]

Originally Posted by hpeer

...It just strikes me that there are soooo many variables that one anchor may work better here and another there.

Agreed. Which is why most of us who have been at it for a while come down to some version of maximizing our anchor systems, combined with developing good anchor skills.

If you're only anchoring in known locations then you can be very narrow in your anchor system design. But for those of us who anchor in a wide variety of locations and conditions, the advice to go as big as is reasonable, remains the best advice (in my view anyway).

[Dockhead]

Originally Posted by Mike OReilly

Agreed. Which is why most of us who have been at it for a while come down to some version of maximizing our anchor systems, combined with developing good anchor skills.

If you're only anchoring in known locations then you can be very narrow in your anchor system design. But for those of us who anchor in a wide variety of locations and conditions, the advice to go as big as is reasonable, remains the best advice (in my view anyway).

Yes, big (in my view too), and choose an anchor which works in the greatest variety of conditions. Big means that even if your anchor loses a big percentage of its holding power in some or another type of seabed, there will still be enough left to hold you.


You say "if you're only anchoring in known location . . . " -- this is also important. A lot of the disagreement on anchoring between different cruisers comes down to this. Most cruisers don't get that far from home, just anchoring on odd weekends in well-chosen weather and spots.


Those of us who are out for months or years at a time, who are often in new places, who might not see a dock for weeks or months at a time, and who therefore often can't choose our weather or bottom type, face a totally different kind of challenge and need a different kind (and size) of anchor, from what it perfectly satisfactory for most cruisers. The maker's sizing recommendations are really not for us, but are probably fine for most.



John on Morgan's Cloud wrote with tongue slightly in cheek that the size of the anchor on the bow is proportional to experience of the owner, but probably it's not that, but rather the type of cruising one does.