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Old 10-03-2013, 18:27   #1
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Knox anchor anyone?

Professor John Knox has written some very interesting articles about anchors and anchor tests, and apparently he is now producing and selling an anchor of his own design. There is more information on his website. Looks to be a new-generation type concave anchor with a rollbar, but it also seems to share some design features with the Super Sarca. Of course, like all anchor companies, he has a lot of claims of superiority. One thing to note is that he has apparently tested his anchor against the competition and is publishing some results on the site.

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Old 11-03-2013, 00:34   #2
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Re: Knox anchor anyone?

Thanks for the link.
It's an interesting design that has the elements that generally result in a good modern anchor. Although it looks like there is a lot weight at the roll bar end of the anchor, which is generally not helpful.
The deep shank means that it may fit boats where normal roll bar anchors do not. Modifying the bow roller to take a roll bar anchor, which is sometimes nessesary can be difficult and the Spade, which solves the problem is very expensive.
Also produced in the UK may give a price advantage to European customers.

The big question is how it performs. It's a pity some the anchor manufacturers make such exaggerated claims. 50 % better than the best anchors we have at the moment ( MS, Rocna and Spade) seems unlikely.
It would be nice to get a new round of tests as a starting point to show which of these new anchor designs show promise.
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Old 11-03-2013, 02:00   #3
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Re: Knox anchor anyone?

Professor Knox is a an academic and scientist of considerable renown and is highly respected in his field. He has also spent the last, at least, 15 years independently testing anchors and has had a series of of meticulous articles published in the UK, YM and PBO. To suggest that he has exaggerated any claims, without substance for the use of the word 'exaggeration' is an insult to Professor Knox' integrity and simply shows a lack of courtesy.

When other workers have had opportunity to assess Professor Knox' claims we might then be able to comment - in the mean time his results are 'claims' and one should not denigrate without real evidence. I, for one, hold Professor Knox in very high regard and hope that his claims can be substantiated - it will be to the benefit to us all.

It merits mentioning that oil rig anchors, some developed from the lowly Bruce, are factorially more efficient than anything we use and a 50% improvement is nothing in their terms.
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Old 11-03-2013, 03:18   #4
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Re: Knox anchor anyone?

It merits mentioning that oil rig anchors, some developed from the lowly Bruce, are factorially more efficient than anything we use and a 50% improvement is nothing in their terms.

Yes but they generaly wiegh 20T
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Old 11-03-2013, 03:32   #5
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Re: Knox anchor anyone?

Very Interesting, Almost like a modernized roll bar concave danforth! It would have an extremely angle for the pointy bit so it should start to pull in easily.

I would perhaps worry that something (like the chain) could get stuck in the slot. I Guess it would be best to set it properly each time, to reduce the risks of an anchor warp going astray...

But It's very good to see something new on the scene. Hopefully it will live up to it's test results. Thanks for the heads up. Also found this interesting, referring to the loads on a 30 footers anchor in different conditions using Knox's test equipment.
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Old 11-03-2013, 04:12   #6
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Re: Knox anchor anyone?

Quote:
Originally Posted by Pacey16 View Post
It merits mentioning that oil rig anchors, some developed from the lowly Bruce, are factorially more efficient than anything we use and a 50% improvement is nothing in their terms.

Yes but they generaly wiegh 20T

If you check with Vryhof they use little models, about the size of our anchors, before they make the bigger ones. I understand that its cheaper and they think the results scale up. My point was only - it is in the realms of possibility so do not deny the possibility without checking.
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Old 11-03-2013, 05:19   #7
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Re: Knox anchor anyone?

It is worth it hunting up Knox's articles, if you can find them. He has a list on his site, but not copies of them, which is a shame. But, here's one. In any case, he has some interesting test apparatus that measures actual loads on the anchor rode. Somewhere amongst his writings are some notes I found interesting, where he indicates that certain size anchors are not as good as other sized anchors of the same design--actual evidence of a scaling effect that some have speculated on.
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Old 11-03-2013, 05:43   #8
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Re: Knox anchor anyone?

Wondering why the slot? Seems like it makes folding back one of the flukes more likely. I noticed also he picked the comparison anchors to suit his study. If you compared the danforth type in efficiency/weight something like the fortress would blow away others, where was delta in efficiency and why left out?
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Old 11-03-2013, 06:00   #9
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Re: Knox anchor anyone?

He had concluded in earlier tests that the Delta wasn't as good as the new-gen anchors so he left it out of this comparison. Not sure about the Fortress. Is it possible that the Fortress is not widely distributed in Europe?
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Old 11-03-2013, 06:01   #10
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Re: Knox anchor anyone?

Quote:
Originally Posted by JonJo View Post
To suggest that he has exaggerated any claims, without substance for the use of the word 'exaggeration' is an insult to Professor Knox' integrity and simply shows a lack of courtesy.
No, it's not an insult, and it doesn't show any lack of courtesy. The plain fact is that exaggerated claims are the standard in the anchor industry. It is what we have grown accustomed to, and come to expect. I'm sure the good professor knows that, and understands that people are going to be dubious of his claims until they have been proven over some period of time in real-life conditions.

What's more, noelex never said that Dr. Knox's claims were exaggerated. He simply pointed out that anchor manufacturers make exaggerated claims (which they do) and then said that 50% better seemed unlikely to him. Seems unlikely to me, too. This is no knock against Dr. Knox's integrity, and if he takes some healthy skepticism as a personal insult then he is very definitely in the wrong business.

I think it would be wonderful if this new anchor turns out to be that much better than anything else that is currently available. But I am not going to be convinced by laboratory tests, or engineering equations. I will be convinced only when real-life experiences, over a period of time, and in a wide range of conditions, proves out the design. In the meantime, I wait, I hope, and I reserve just a bit of skepticism.
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Old 11-03-2013, 06:07   #11
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Re: Knox anchor anyone?

Quote:
I would perhaps worry that something (like the chain) could get stuck in the slot.
Or a rock, a quahog shell, or whatever trash is on the bottom.
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Old 11-03-2013, 06:23   #12
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Re: Knox anchor anyone?

the lowly bruce is an awesome anchor and i want 3 more, so when you all buy these new fangled things, please send me your 30 kg bruce anchors....
thankyou.
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Old 11-03-2013, 06:37   #13
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Re: Knox anchor anyone?

Quote:
the lowly bruce is an awesome anchor and i want 3 more, so when you all buy these new fangled things, please send me your 30 kg bruce anchors....
thankyou.
And, there is the perfect counterexample to all the anchor tests that indicate the Bruce is one of the worst anchors for holding power. Yet, experienced boaters seem to like them, at least in larger sizes. I've noticed two things about Bruce anchors, and I am not a fan. One is that those who use very large ones seem to get better results. Two, they seem to perform better in hard, difficult anchoring situations, like are often found in the Caribbean or the Pacific, where cruisers tend to go. Judging from how often I have had a Bruce-anchored boat drag into me, they do not perform so well in areas with good holding ground--deep mud, deep sand, etc.

My point being, that anchor tests are usually concentrated on maximum holding power, which is not the only thing. After all, how many nights at anchor is your anchor tested for holding power? Very few. Yet, virtually every time you use it setting ability is tested.
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Old 11-03-2013, 06:50   #14
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Re: Knox anchor anyone?

anchor testing is done in a controlled environment, not in reality.
and my bruce is not too big for my boat. is perfect. works well in this stuff called mexican bottom sand and rocks and mud. if they drag so much, why are the oil rigs not dragging allover gom......

never had a boat anchored with a bruce drag onto me. only the rocna user who couldnt anchor in rocks, and a cqr who was plowing the corn fields below the surface, and my own cqr that drug when my chain dropped into a channel.
there are many new fangled anchors that all look the same and donot fit on older bow rollers and sprits without modifications.
i willstick with my bruce and cqr, thankyou.
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Old 11-03-2013, 11:24   #15
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Re: Knox anchor anyone?

One of the problems people are having today is that real Bruce anchors are scarce, and some of the cheap knock-offs don't seem to be very strong or have the right shape. I suspect the originals were better. Also, you need a bigger size than other anchors in order to get decent holding power, though I wouldn't want one after seeing all the draggers with them. Here's a photo of one going up on the reef to my portside in the San Blas.

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