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Old 01-01-2015, 07:12 AM   #221
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Noelex,

Maybe, for the common good, you could share Prof Knox formula.
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Old 01-01-2015, 07:20 AM   #222
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>Anchor forces rise roughly as the square of the wind speed so the force rises much more dramatically with an increase in wind speed than might be imagined <

Which is why thunder storms are so much fun!

13 knots= 45 Kgf
30 knots = 241 Kgf

Fun begins in the puffs,, which frequently will be 25%-50% higher than the constant wind speed.

50 mph in the thunderstorm = 60- 75 in the puffs and the anchor mfg.recommended watch fob begins to look rather small.
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Old 01-01-2015, 09:31 AM   #223
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Originally Posted by Fortress Anchors View Post

During the Sailing Foundation tests (summary below), pulls were conducted from straight line, 90 and 180 angles. The maximum amount of pull was approximately 4,000 lbs, and the 20+ lb FX-37 exceeded that amount in every direction. No other much heavier steel anchor came close.

Djbangi asked about the SuperMax earlier, and I see that's included in the Sailing Foundation tests... identified as MAX 17, which IIRC is the non-pivoting version.

I can't interpret the charts exactly without the key to asterisk and footnotes, but it looks like it did well enough (in some chart columns) -- when set properly. Second only to the FX-37, I think?

I think the instructions for setting the non-pivoting SuperMax are different from what ours are (i.e., for the pivoting model). Can't remember details...

-Chris
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Old 01-01-2015, 09:47 AM   #224
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In most cases an anchor that develops a high list like the Danforth/Fortress when changing direction will reset in the new direction without any problems. However, it is very disconcerting to see an anchor with very little grip on the bottom as it rotates. A gust at the wrong time, when the anchor is rotating, will see the anchor sliding backwards.

Underwater, I see Fortress/Danforth anchors develop this high list with minimal grip of the flukes quite frequently.

I think I'd have been inclined to interpret this as probably an anchor which has not yet been properly set. And I'd have suspected whatever poor technique caused that condition could have been applied to any anchor style.

Maybe the skipper(s) just threw it (them) overboard, opened a beverage, and went swimming?

-Chris
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Old 01-01-2015, 11:57 AM   #225
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Anchor forces rise roughly as the square of the windspeed so the force rises much more dramatically with an increase in windspeed than might be imagined.
All too much focusing on wind and pseudo mathematics. Some of us could baffle this subject even more by bringing up rope/chain selection, wind, wave and current force determination using differential equations.

But back to reality. Add a few big waves tugging viciously on the anchor and you really begin to understand the entire subject is as much an art as science. Almost a full century of Danforth style anchors successfully being used in all sorts of bottoms is more than anecdotal. It is just common sense to use one as either a primary or better yet a backup with the more easily stowed and "good enough" newer designs ever so frequently used as primary.
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Old 01-01-2015, 01:51 PM   #226
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Way back at post #1 I stated this particular thread but had little to do with starting the long running controversy regarding anchors and ground tackle. Some things I take away from the thread and controversy in general mostly recurrent old hat stuff are: #1 many people get passionate about anchors. #2 Those who sell products, anchors included, will defend their product and endeavor to advertise it. #3 There is a lot about the art and science of anchoring that is known and still unknown. #4 Tests preformed in labs and in the field do not always reflect accurately on how things play out in the real world There are often too many variables to account for particularly when humans are involved in the formulas. Regarding the small piece of the overall anchoring and ground tackle universe the Fortress test or soft mud test sponsored by Fortress reinforces the fairly well known ability of Danforth anchors to run up high holding power readings in mud substrates. The finding that several well thought of types of anchors did not do as well raised interest and questions as to why. This finding seems to disagree with the experience of many boaters and the question raised is why? The answers may or may not be something that can be demonstrated with further testing but it probably should be done. Since there does not appear to be a significant feed back from the general anchoring public about the poor testing anchors causing problems there may be something else going on here. The test results could be either floored or the parameters insignificant as compared to how and where people anchor. The test in question even with its very narrow field of view does give us information, but the big issue is how do we interpret and apply that information. For example if a tire company demonstrates that its product grips better in snow than others and some highly touted tires do not do so well what is the overall significance? Does the good gripping tie do well on dry road does it make noise does it stop well does it wear well does it handle high speed etc. etc. etc. Are people going to be happy with that tire for general use? If all the tires in the test were submitted to the many other conditions how would the supper snow tire fare? Which of all the tires would be the best compromise? Yes we can change anchors for different substrates and some do,but that can get old for the typical cruiser who I believe would like the best all around unit for the bow pulpit. As I pointed out before this is at least a 15 round bout and we are only in the early rounds.
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Old 01-01-2015, 01:54 PM   #227
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I'm by no means anchoring in your conditions Tom, nevertheless I'm impressed by how my woefully undersized genuine Danforth holds in some really fluffy muck.
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Old 01-01-2015, 02:09 PM   #228
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Originally Posted by eyschulman View Post
This finding seems to disagree with the experience of many boaters and the question raised is why? The answers may or may not be something that can be demonstrated with further testing but it probably should be done. Since there does not appear to be a significant feed back from the general anchoring public about the poor testing anchors causing problems there may be something else going on here.
OR, maybe folks dont like hearing that their baby might be ugly. Even if it is a highly polished ULTRA.
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Old 01-01-2015, 02:50 PM   #229
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OR, maybe folks dont like hearing that their baby might be ugly. Even if it is a highly polished ULTRA.
Not that I am here to sell Ultras but did they not test fairly well in the Fortress test? The shine and sleek shape I find seems to have an added benefit in mud. I have the impression that the anchor comes up cleaner and washes of easier than some other anchors I have owned, but all this is outside of the target range which is the Fortress test and how it relates to the questions raised regarding the other than Fortress anchors. If my whole post is contemplated rather than part out of context the need for ultra bashing disappears.
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Old 01-01-2015, 04:36 PM   #230
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Eyschulman,

FWIW, I thought that post #226 was an excellent analogy.


Happy New Year,
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Old 01-01-2015, 05:07 PM   #231
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I think eyschulman left out the most important part.

The test exposed a clear weakness in the very popular Rocna that many thought was a flawless product that could do no wrong. There's no such anchor. There never will be and the over the top enthusiasm for the Rocna is now in much more realistic focus.
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Old 01-01-2015, 05:36 PM   #232
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The shine and sleek shape I find seems to have an added benefit in mud. I have the impression that the anchor comes up cleaner and washes of easier than some other anchors I have owned,
I knew eventually I'd get some real value out of this discussion. Up to now, I couldn't substantiate SS anchors to the Admiral. Thanks eyeschulman!
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Old 01-01-2015, 05:53 PM   #233
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The Rocna is still a perfect anchor and the best one on the planet. It was the mud Fortress used that was defective. Anyone can see that.
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Old 01-01-2015, 06:13 PM   #234
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The Rocna is still a perfect anchor and the best one on the planet. It was the mud Fortress used that was defective. Anyone can see that.
Right on! We bought a RockStarNa last year, so it's obviously the best.

(But..., er, just in case it isn't, though we are never (well, almost never) wrong, we keep an FX 23 on a second rode in the laz ready to deploy and the knock off Bruce that came with the boat in the garage ready to deploy to hold down said garage in a windstorm. True fact that.)
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Old 01-01-2015, 09:15 PM   #235
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David re the Bruce I've been thinking about wind protection for my newest carport. The rods meant to hold it down largely went into loose ground.
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Old 01-01-2015, 09:26 PM   #236
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...we keep an FX 23 on a second rode in the laz ready to deploy ...
We have an FX23 on the swimstep to use as a stern anchor, or as the main anchor should we encounter conditions that our primary anchor won't handle. So far, we've only needed the Fortress as a stern anchor. Our primary anchor has to date handled all the bottom conditions it's encountered, including holding two boats in mushy mud, albeit under fairly non-stressful conditions. But knowing the Danforth design's excellent performance in mud and sand, we thought it would be wise to have such an anchor design on board.

And we can attest to the superiority of the Bruce anchor as a garage stabilization component. In our case, it propped open a door, but had we experienced a high wind situation I'm sure that, buried deeply in the garden, it would have done an equally superb job of assisting in keeping the garage intact

I'm wondering if Bruce & Co. missed the marketing train with this anchor. Instead of pawning if off on unsuspecting boaters, perhaps they should have targeted the home construction industry. For example, would surrounding a house with buried Bruce anchors cross-connected to the foundation meet the building code requirements for structural stability in an earthquake area like Puget Sound?
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Old 01-01-2015, 09:42 PM   #237
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We have an FX23 on the swimstep to use as a stern anchor, or as the main anchor should we encounter conditions that our primary anchor won't handle. So far, we've only needed the Fortress as a stern anchor. Our primary anchor has to date handled all the bottom conditions it's encountered, including holding two boats in mushy mud, albeit under fairly non-stressful conditions. But knowing the Danforth design's excellent performance in mud and sand, we thought it would be wise to have such an anchor design on board.

And we can attest to the superiority of the Bruce anchor as a garage stabilization component. In our case, it propped open a door, but had we experienced a high wind situation I'm sure that, buried deeply in the garden, it would have done an equally superb job of assisting in keeping the garage intact

I'm wondering if Bruce & Co. missed the marketing train with this anchor. Instead of pawning if off on unsuspecting boaters, perhaps they should have targeted the home construction industry. For example, would surrounding a house with buried Bruce anchors cross-connected to the foundation meet the building code requirements for structural stability in an earthquake area like Puget Sound?
LOL, you are completely relentless...
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Old 01-01-2015, 09:44 PM   #238
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So I have a Bruce and a Fortress. So anchor #2 by popular acclaim is taken care of. What anchor would I best be advised to purchase in the 85# area that would replace my (never drags & always sets) foundation ready Bruce and fits in the same length anchor "bed"?


I can't take this abuse anymore!
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Old 01-01-2015, 10:03 PM   #239
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So I have a Bruce and a Fortress. So anchor #2 by popular acclaim is taken care of. What anchor would I best be advised to purchase in the 85# area that would replace my (never drags & always sets) foundation ready Bruce and fits in the same length anchor "bed"?


I can't take this abuse anymore!
Since your 85# Bruce weighs 85 pounds, my guess is that it's up in the weight range where this design tends to work. And since your Bruce has so far never let you down, then it would make absolutely no sense to replace it. Had our much lighter Bruce never let us down, it would still be on the pulpit.

However..... you do have to deal with the issue of your anchor being of the "old generation" of designs and is therefore sort of like wearing a 1970's pastel leisure suit. So what I would suggest is that you have someone fabricate a "rollbar suit," something made of some lightweight, weatherproof material that can be clipped around your Bruce to make it appear, at least from 15 or 20 feet away, to be a new-generation rollbar anchor. This "anchor shroud," we'll call it, could even be chrome-plated to bring it in line with the current trend in polished bow bling.

So while underway or in a harbor, everyone will assume you are up to speed with the most current trend in ground tackle. Then, when you actually need to use your anchor, it's a simple matter of removing and stowing the anchor shroud and using your Bruce in the manner to which you are accustomed.
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Old 01-01-2015, 10:34 PM   #240
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As Noelex was unable to provide the formula this is a formula that John Knox used in one of his articles, 2002, and he cross referenced it to articles in YM 1099 and PBO 386 (which he might have written - but the formula could have been developed by A N Other).

Peak cable Tension in Kg

= (1/500) x (LOA metres - squared) x (wind speed knots squared)

The formula is contingent on the idea that wind resistance of a vessel is proportional to its frontal area and this roughly proportional to LOA squared. This might or might not be true of a yacht (modern yachts seem to have much higher windage than those of the 1990s) but I suspect not true of a trawler.

The formula completely falls apart if you try to apply it to 4 or 5 vessels rafted up.
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