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Old 10-22-2011, 08:38 AM   #21
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Do anchors scale?

FWIW,

In our 22 and 26-foot cruisers we've anchored 700+ nights, mostly all up and down the Inside Passage, in winds to 45 knots.* Until this summer, always with a genuine Bruce, and not a very big one either (5kg and 7.5kg). Our rode is 40 feet of chain spliced to 300 feet of rope.

Our backup anchor is a Fortress, which does the trick in the rare soft mud bottom where the Bruce is inclined to drag endlessly. It's also a great stern anchor.*

Except in soft mud, or a thin coating of sand over a slickrock bottom (Lake Powell) the Bruce has never dragged once properly set.* It does take some resetting in thick kelp.

Despite this successful Bruce experience, I decided to switch to a 10kg Rocna for this year, for more size as much as anything.* I'm absolutely delighted with how fast it sets even in some kelp, and it seems clear from everything I've read that its holding power in a very strong wind would be a good bit better than my smaller Bruce.* And so far it shows no sign of bending.* (The Bruce wouldn't bend under any imaginable circumstances - Strong!)

*


-- Edited by RCook on Saturday 22nd of October 2011 08:42:30 AM
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Old 10-22-2011, 09:22 AM   #22
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RE: Do anchors scale?

Richard, while not disagreeing with your findings, it is*incongruent that both you and Marin replaced smaller Bruce's with bigger Rocna's. Rocna's hype is that a superior design allows for a lighter anchor.

So my take is you both are happier with* 50-100% heavier anchors.*That one fact alone makes a lot of sense.

*
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Old 10-22-2011, 09:33 AM   #23
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RE: Do anchors scale?

Scott,

Loved your head buried deep talk. haha It's great when you get the chance to sling a good one. * *I don't see how ships stay put w those Navy anchors. Compared to the ship they are very small (despite the fact that they are monstrous) and they probably never bury. I suspect they act like a bulldozer more than an anchor. But some fishermen do use them. As far as scaling goes there is an aspect of scaling I have never thought of (until this morning) and it could help explain why big ships can anchor w relatively small very low performance anchors and stay put. How fast is wind moving over a ship? How long does it take wind to get from the bow of a ship to the stern. We can measure it in knots but does it matter how long it takes for the wind to get from the bow of a vessel to the stern? The wind speed question may be like or a bit like the hull speed question. Perhaps a 30 knot wind is (in some meaningful way) more like a 6 mph gentle breeze over a small anchored trawler yacht. I lived in Vancouver BC for a year and remember the ships anchored in English Bay. If they dragged anchor they either had to summon a tug or fire up their main engine to move ahead and reset their anchor. Never saw any evidence of that. You work on ships (I gather) so tell us *..how often do they drag? Fishermen do drag in a blow (w their big anchors and heavy chain) and they think more chain and a bigger anchor is the solution to not dragging or no dragging. I think most of the time they probably start the engine and put it in gear to take some strain off the rode. That's only a guess as I don't know that they do that but that's what I would do. Anyway I have no idea or knowledge that shows that wind "scales". Perhaps scaling (if it exists in any life altering amount) is dependant on aerodynamics as well as hydrodynamics. Scott, do you know enough about the numbers to tell us how many pounds of anchor is typically used for a given displacement of freighters or other large vessels? Looks like we use about one pound of anchor for every 6 or 700 lbs of boat on our trawlers. I'm sure ships have much more boat hang'in on much less anchor weight. To have a vessel to anchor weight ratio like a ship perhaps we would only get a 5 to 10 lb anchor to do the job. Then there is the wind question *...unless it's linear. Never heard of a building being blown over. Just the windows being blown out. Perhaps the answer to ships and buildings comes from the same source. Thanks for your posts Scott. More ideas lead to yet more ideas and perhaps knowledge.
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Old 10-22-2011, 11:45 AM   #24
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Do anchors scale?

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sunchaser wrote:
Richard, while not disagreeing with your findings, it is*incongruent that both you and Marin replaced smaller Bruce's with bigger Rocna's. Rocna's hype is that a superior design allows for a lighter anchor.

So my take is you both are happier with* 50-100% heavier anchors.*That one fact alone makes a lot of sense.

*
Our Rocna is not 50% larger than our Bruce.* It is just one size up-- only eleven pounds heavier--- the same weight as the Bruces on some of our friend's* 36' boats' who have experienced numerous instances of their Bruce dragging or breaking free under pressure.* Thats my whole point--- going from a 33# to a 44# Bruce apparently makes zero difference to the holding power for a boat the size and weight of ours and the boats of people we know who've had the same experience.

Besides, while weight certainly contributes to an anchor's effectiveness, the design is much more important I believe.* If this was not true, the Fortress wouldn't work, yet it consistently tops out the tests as having the best holding in the bottoms for which its design is suited.* Simply looking at a Bruce design, and the design of a Rocna, Sarca, Manson, Super Max, Danforth, Eric's XYZ, even a CQR, it seems obvious to me why the Bruce has such low holding power.* At the time we bought our Bruce we knew virtually nothing about anchors and anchor designs so we went with what was the most popular in this area for boats like our GB.* Now, 13 years later, we know a lot more about anchors and how their designs work, or don't work.

I'm sorry but after our several years of experience with a Bruce, and the experience of a fair number of other boaters we've met who have, or had, a Bruce, I will never be convinced that it is an anchor to be trusted in the smaller sizes that are used on boats like ours.* If our next boat was a North Sea oil exploration rig, you bet, I'd be in line for a Bruce with a semi-tractor and lowboy trailer to carry it to the rig.* But for a 36' foot boat like ours, I consider a "properly" sized Bruce to be no more reliable than a rock.* And not a very big rock at that.

We've had a few people ask to buy our Bruce since we aren't using it any more and Bruce no longer makes small anchors..* We won't sell it to them because we believe selling something has has proven itself to be unreliable-- particularly a safety item like an anchor--- is irresponsible.* If the day comes we don't need it to prop open the door in our garage we will throw it away.

Eric says the Bruce is common and very popular up in his neck of the woods.* It is down here, too, probably even more so.* It's why we bought one.* But every comment we heard at the time about the benefits of the Bruce referred to its ability to set in a variety of bottoms.* NOBODY said a word about holding power, probably because in our mostly protected anchorages here people aren't faced with riding out 50-knot winds and big waves.* So we bought a Bruce.

Worked great under the typical 0-20 knot conditions we get here.* But when the wind kicked up higher or the bottom was less ideal for its design, it invariably grew legs and wandered off.* If it had just been us having this problem we would have looked to our anchoring technique.* But we heard-- and still hear--- this same story time and time again from other boaters.

Bottom line is that, regardless of the "never had a problem with our Bruce" testimonials from other boaters, including ones on this forum, we simply lost our faith in it and no longer trusted it.* At anchor, if the wind blew at all at night, we would lie in our berth worrying if it was going to blow harder and if it did would the Bruce hold.* And if you can't trust your ground tackle, it's time to look for something different.* The experiences of other boaters is irrelevant-- the only thing that matters is what happens with your boat.* And the Bruce let us down too many times to be considered reliable.* The fact it was letting down a lot of other boaters we knew was just the icing on the cake.* So it went.

Eric has rightly said that if we'd have had a larger Bruce it would have worked for us.* We know that going from a 33# to a 44# Bruce would have made no difference in reliability at all.* So based on what I've heard, read, and observed in the years we've been doing this kind of boating, for a Bruce to be truly effective and reliable on our boat, it would have to be 70 or 80 or 100 pounds in weight.* And we're simply not set up to deal with an anchor that large and heavy.* So we went with an anchor with a superior design instead.


-- Edited by Marin on Saturday 22nd of October 2011 12:52:09 PM
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Old 10-22-2011, 06:57 PM   #25
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RE: Do anchors scale?

Before I buy a claw to experiment with on line I decided to check on what was available in Craig. Boat/OB store closed on Saturday. Nothing at JT Brown. Two at sporting goods store *..one about 75 lbs and one 22 lbs. Odd that it's weight was marked in lbs only and no brand name to be found. I want a smaller one so I can stress it more easily. Somebody said the Bruce has an shank that could'nt be bent but I saw several in Craig that were bent to very bent. One large one on a seine boat was bent almost 90 degrees. I was surprised it did'nt break. Funny that while I was looking at the Claw anchors in the sporting goods store a commercial fisherman came up to me and raved about the Bruce anchor and about all the many years he'd been fishing up here. Thought about telling him about Marin and asking him to join our discussion here. Thought about it for about 3 seconds.*
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Old 10-23-2011, 01:24 AM   #26
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Do anchors scale?

Quote:
nomadwilly wrote:
... a commercial fisherman came up to me and raved about the Bruce anchor and about all the many years he'd been fishing up here.
People who have so far had good luck with an anchor--- any anchor--- always rave about how great it is.* Every anchor is great until the day it lets you down. If you buy that 75 pound claw, Eric, I will bet money it will never drag on you and Nomad Willy :-)


-- Edited by Marin on Sunday 23rd of October 2011 01:26:07 AM
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Old 10-23-2011, 02:02 AM   #27
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Do anchors scale?

Quote:
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I'll tell you a real disadvantage of a Danforth-type anchor, and it's got nothing to do with setting or holding. If your boat has a short pulpit and a plumb or nearly plumb bow-- like a GB-- if the anchor comes up out of the water and starts to rotate or swing (or both) for some reason like boat movement, wind, whatever, that long stock will come around and whack the stem of your boat, usually several times as it comes up to the pulpit. Our boat has a whole series of chips and dings in the gelcoat on the stem from the previous Danforth-type anchor that was on it prior to our purchasing it. One of these days I'm going to use these as a way of practicing filling and fairing gelcoat dings and chips, which we'll have to a lot of prior to painting the boat (someday).
*That's one of several reasons I'm not much of a fan for the Danforth type.* Besides, they frequently do a good job pinching my fingers since the shank moves separately from the flukes, and they bring up a "ton" of mud.* I'd bet both the Rocna and Manson Supreme would also bring up lots of muck.* I'm not a fan of mud, muck, mire, and mess.


-- Edited by markpierce on Sunday 23rd of October 2011 02:06:01 AM
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Old 10-23-2011, 07:57 AM   #28
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RE: Do anchors scale?

I think the comment about people swearing by the anchor they have - until, that is, it lets them down is so true. I was at a Women's Health Conference at the Hyatt Regency, Sanctuary Cove today...yes it's a hard job, but somebody's got to do it...and after the conference lunch was over, I went for a walk down to the marina - which is large, and holds a lot of boats. Thinking of this thread, I walked right round it and took note of the anchor type most favoured. It still came out hands down, the plough/CQR type by a huge margin. I think this is a beautiful example of the opening statement, and also the flip-side to that, which is, most people stick with what others use, and also what comes with the boat. Unless and until they have a fright....? In the case of Moreton Bay, one is unlikely to ever suffer a severe fright, even if you drag, and it is quite sheltered and mostly mud/sand bottom, so pretty forgiving. So not many will ever be finding themselves in strife because they are using an anchor which can indeed be found wanting. Of course another important reason, probably the most important, as to why so many boats have this type of anchor here is simply they are sold with them..which brings the discussion full circle. Why? - because they fit virtually all bow set-ups so well, and deploy and retrieve so easily. So not much changes. Yet my view of plough anchors, based on my own experience is much like Marin's of the Bruce. I have had it fail me in a blow and nearly ended up on a lee shore, and I have had it fail to set in even moderate conditions on weedy and shingley bottoms, and to me that is unacceptable. That is why when this happened, and by chance not long after I attended the Sanctuary Cove Boat Show at this same venue some 8 yrs ago, saw a video demonstrating how the Super Sarca worked in real-life circumstances, recognised immediately how its unique design contributed to this, and was convinced. I ordered one then and there, and have never had cause to regret that even in some fairly hairy situations since...although, like the rest of you I'm sure, I always try to avoid being in a potentially hairy situation if I can. I'm not an overly brave or foolhardy person.

If interested to see what I mean, check out the snatch test video below....if you hate anchor discussions then don't - just keep loving your anchor, it probably won't fail...

http://www.anchorright.com.au/sarca/video
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Old 10-23-2011, 10:10 AM   #29
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RE: Do anchors scale?

Quote:
markpierce wrote:I'd bet both the Rocna and Manson Supreme would also bring up lots of muck.* I'm not a fan of mud, muck, mire, and mess.
Yes, they do if it's a sticky-mud bottom, and I'm glad they do because it's an indication of how deep and solidly they set.* We have a monstrous (for a boat) washdown pump so blasting the all-chain rode and anchor totally clean of mud is a breeze as they come aboard.* We've never had any mud or muck in our anchor locker.
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Old 10-23-2011, 10:31 AM   #30
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RE: Do anchors scale?

Marin,

I don't think the Supreme or the Rocna penetrate very deep unless they are in very soft stuff. And I think that the roll bar reduces their ability to penetrate much after initial setting. I just looked at the Rocna site and see that that smug Smith guy is still prominent with Rocna. Not good. Both anchors don't seem to suffer much from reduced penetration and more importantly I'm sure the roll bars contribute to holding power as they obviously impede the anchor's fwd progress through the substrate. And as w any anchor being a "hook" they all bring up stuff from the bottom *...or the bottom itself. I clean my anchors w a brush and only one cleans easily w the brush ..the XYZ. The Supreme is difficult to clean.
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Old 10-23-2011, 10:59 AM   #31
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RE: Do anchors scale?

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nomadwilly wrote:
Marin,

I don't think the Supreme or the Rocna penetrate very deep unless they are in very soft stuff. And I think that the roll bar reduces their ability to penetrate much after initial setting.
I guess that depends on which video you watch :-)* In the underwater videos I've seen of Bugel and Rocna anchors setting both of them just disappear into the bottom or dig in until just the very top of the rollbar is barely visoble.* This was in sand and firm mud as I recall.
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Old 10-23-2011, 01:39 PM   #32
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RE: Do anchors scale?

That's not deep Marin. One, 2 and 3' is deep. If you put a drag chute on the top of the tail of an airplane it would obviously pitch up and try to climb. The roll bars are considerably above the center of drag on the anchors use them and it's obvious they will pitch the anchor up as it moves fwd. Not good. The roll bar and the "up elevator" style trailing edge both probably contribute to the anchors poor short scope performance as mentioned in several to many anchor tests. Fortunately the pull on the shank mostly overcomes the up pitching tendency or the anchors would'nt work at all. Excluding whatever the shank may contribute to the up elevator force the XYZ has a "down Elevator" trailing edge that insures the fluke pitches down and continues to penetrate deeper. If the roll bar anchors could penetrate deeper their short scope performance would be improved.
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Old 10-24-2011, 05:43 PM   #33
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Do anchors scale?

In one of Rocna's videos their anchor disappears completely into the bottom (wet sand) and they have to dig down to find it. But I know you don't believe anything Rocna says about anything which is why I didn't mention this in my post :-)

And I think you may be over-rating this up-elevator, down-elevator business. Aircraft controls have effect because of their speed and the very fast flow of air over them which generates tremendous pressure (which caused the Reno Air Race accident, for example). An anchor oozing through the bottom at a snail's pace isn't going to be affected anywhere near what aircraft controls will be. So it's my guess that the little angle to the base of the fluke of the Rocna and other anchors, while it looks like it might do something and is probably why the designer included it, in reality doesn't do much at all regardless if it's angled up or down. The angle of the fluke to the direction of pull, the shape of the fluke, and so on, have a huge effect on what the anchor does when you pull it along the bottom. That little three of four inch lip of slightly bent steel I bet doesn't generate any influential force at all.


-- Edited by Marin on Monday 24th of October 2011 05:44:11 PM
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Old 10-24-2011, 09:33 PM   #34
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RE: Do anchors scale?

I agree with that. The fluke/shank angle is everything in this case. That and the sharpness and shape of the actual fluke tip and blade.
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Old 10-24-2011, 10:08 PM   #35
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RE: Do anchors scale?

Not sure what you're say'in here Peter. Sharpness yes. I wonder if one got out a grinder and made the claw flukes a lot sharper (would only take a few minutes) if the dang thing would work better? Don't see how it could harm it unless you made them too thin and they broke. Yea I know the rust. Some of these claws are so cheap maybe I'll do that. Marin I think the up elevator element is there and working fine but counter acted by other forces. Do'nt worry about the penetration thing Marin as you're Rocna and the other roll bar guys seem to work fine penetrating as far as they do. I think the Delta and Spade penetrate deeper * *...but don't seem to work any better anyway. I think the up elevator on the Rocna is put there to increase holding power just like it is on the Spade. I think the angle of the shank and fluke overpower the trailing edge elevators and provide more resistance and holding power. The "elevators" have a significant effect I'm sure as my XYZ would'nt even set without it's down elevators. Thought about you today Marin * .....was looking at a GB 36 single engined woodie.
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Old 10-24-2011, 10:38 PM   #36
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RE: Do anchors scale?

Quote:
nomadwilly wrote:
.....was looking at a GB 36 single engined woodie.
*My guess is sharpening the edges of the flukes on a Bruce would help it set faster and perhaps a bit deeper.* Not sure if it would do enough to overcome the basic deficiencies of the design that make themselves so apparent in the smaller sizes, though.

A GB36 woody single can be*a very*nice, economical boat to buy and operate.... IF.... the structure is sound and has been well maintained and protected from the elements.* There are a number of woodie owners on the Grand Banks owners forum and from what I can tell their boats are probably in better condition than the average twenty or thirty year old fiberglass boat.* But if they get away from you...... it can be a long uphill race to catch back up again as I'm sure you know.
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Old 10-25-2011, 01:56 PM   #37
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RE: Do anchors scale?

Quote:
Peter B wrote:
The fluke/shank angle is everything in this case. That and the sharpness and shape of the actual fluke tip and blade.
*It is all about the pressure on the point. either weighted or by design.

A spade, plow, Roll bar or the like is the best.

A larger anchor allows you to sleep better at night.

SD
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Old 10-25-2011, 02:26 PM   #38
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RE: Do anchors scale?

Dude,

On the test that involved the Rocna, Supreme and Ray (Bruce/claw) the claw had by far the greatest weight on it's fluke when in position to set. Perhaps that's why they set so quick. See post w quote from the anchor test on Anchor design and Performance.
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