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Old 12-29-2015, 07:44 AM   #21
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"Danforths in my experience are handicapped by poor performance during pull direction changes (wind shifts)."

Operator problem.

Mr Ogg inventor of the Danforth in his book always suggests 2 or more anchors to solve this problem.

A 12 H stern anchor , hand set ,will solve the "problem" in under 2 min of effort.
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Old 12-29-2015, 01:09 PM   #22
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A design feature of the Posidonia anchor almost unique is the high or fwd attach point of the shank .. to the anchor. Almost all Danforths have flukes attached at the crown or nearly so. The Posidonia, Manson Ultimus (and probably others) have flukes attached much higher .. much closer to the center of the fluke area. Anchors w the shank attached to the crown like Danforths have high bending forces and probably need a very shallow throat angle to keep the flukes down and in the seabed. Can you imagine a mushroom anchor w the shank attached to the rim (outer edge) of the fluke? Would break right off if it ever set. And of course a Danforth w a 90 degree throat angle would just jack itself up and tip over.

However the ideal attach point (of the fluke) is near the center of the fluke area. Danforth anchors have light flukes and would be next to impossible to set if the shank attach point tended to lift the flukes even slightly. So their shanks are attached where 100% of the fluke weight is felt (in varying degrees) on the fluke tips.

The big stockless anchors have a crown shape that raises the back of the anchor up and and transfers downforce to the fluke tips. In addition the much greater weight puts a lot of pressure on the fluke tips. So much so (on both counts) that the attach point of the shank can be raised bringing it much closer to the center of the fluke area. The larger fluke area of the Posidonia anchor helps a lot but the shank attach point probably is the main reason the anchor is rated for SHHP status.


Re the Danforth veering an anchor test by Practical Sailor magazine (Jan 15 2001) addressed that issue directly.
West performance Rolled up 45 degrees, pivoted on one fluke
flattened. Reset in 2'
Fortress F-X 16 Swiveled very flat, crown moved very
little.
Danforth Deepset ll Did not break out flukes. Stayed buried.

Seemed the Danforth types did very well veering.
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Old 12-29-2015, 03:14 PM   #23
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Eric-- I consider an anchor to be unset when it's not holding the boat anymore.
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Old 12-29-2015, 03:53 PM   #24
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That's a good one Marin.

But w no wind or current your chain holds the boat w the anchor just lay'in on the bottom.

How would you like to have one of those Posidiona stockless anchors on your bow? An extra 100lbs but think of all the attention you'd get.
Seriously I wonder if these "stockless" anchors will evolve to be suitable for toy boats? It would suffer like the Bruce. Not very compatible w bow pulpits. But your faforite anchor did fairly well w that limitation. Merry Hollidays!
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Old 12-29-2015, 04:07 PM   #25
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But w no wind or current your chain holds the boat w the anchor just lay'in on the bottom.
With no wind or current we don't need an anchor.

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How would you like to have one of those Posidiona stockless anchors on your bow? !
We've already got the world's best all-around anchor design on our pulpit. So why would we want to swap that out for something less?
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Old 12-29-2015, 04:58 PM   #26
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It's old now Marin.
Gotta get something new.

Seriously though I have plenty of good anchors (at least the haven't dragged yet). But the potential for these "stockless anchors" to replace the anchors we now use is at least very interesting. It would be nice to know what the good and bad features of all anchors .. modern or old .. Would be. Not just a contest of the latest fad anchors. Gotta get a haircut .....
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Old 12-29-2015, 07:56 PM   #27
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Almost all Danforths have flukes attached at the crown or nearly so. The Posidonia, Manson Ultimus (and probably others) have flukes attached much higher .. much closer to the center of the fluke area.
Bingo.

This makes sense, and reminded me of a snow fluke; an emergency anchor point used in mountaineering. There are two attachment points on a snow fluke which align the direction of pull to near centre, exactly what you were talking about.

https://en.wikipedia.org/wiki/Snow_protection

The crown shape of the Posidonia would have two benefits then, because of the increased amount of material piled up and the direction of pull coming from lower down in that pile.
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Old 12-29-2015, 09:55 PM   #28
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That big square shank probably impedes penetration. I'll bet a shank cross section like a Fortress would help.

Murray I wonder what advantage those holes are in the snow fluke?
We should ask Rex.
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Old 12-30-2015, 09:17 PM   #29
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It's old now Marin.
Gotta get something new.
Eric-- The only time I replace something old with something new is when the new something is a better design or works better than the old something. Which is the case 99.99999 percent of the time.

But in the case of anchors Pete Smith got it right the first time around; nothing since has a better design or works better on an all-around basis. So if it ain't broke, why fix it, right.
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Old 12-30-2015, 09:49 PM   #30
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Just funn'in ya Marin,
I think I've come up w something better than the roll bar on my Supreme. I'll post some pics later. The boss and the Vulcan gave me the idea. I welded back something I cut off my XYZ .. decided it needed the ballast. Looks like we've got 10 days coming up w no rain.
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Old 12-30-2015, 10:03 PM   #31
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Just funn'in you.
I know.


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Looks like we've got 10 days coming up w no rain.
We drove today over Stevens Pass to Leavenworth for lunch, then back home via Blewett and Snoqualmie passes. Beautiful weather, lots of snow (as opposed to last winter), great day.

Got home to a message that our PNW boat, after three months in and out of the yard to troubleshoot, track down and fix a serious, complex and frustrating problem is back in the water with the problems solved and ready for us to sea trial for the final adjustments with the yard's chief mechanic. So we'll be able to start taking advantage of the stretches of boatable weather between now and when it starts getting too crowded around here come June.
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Old 03-23-2016, 12:55 AM   #32
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My gift to Eric and the forum is a new anchor to discuss

The Posidonia PTW+ Anchor, the first stockless anchor to be rated by Lloyds as super high holding power;

POSIDONIA SRL - Products > Anchors > Yacht anchors > PTW+ Anchors

Italian made, comes in sizes down to 17kg (pretty suspect at that size I bet) but would look pretty damn cool snuggled up against the bow through the hawse pipe of a medium to large sized trawler...

I have never seen one of these in real life but it seems I may be about to.
My offer has been accepted on the boat in the picture here and I believe there are two of these bad boys hanging through the hawse pipes on this bow. I am headed to Amsterdam in a couple of weeks to experience a sea trail and survey that is not in my native language. That ought to be interesting. I will also be interested in getting a close look at these anchors.
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Old 03-23-2016, 01:04 AM   #33
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I have never seen one of these in real life but it seems I may be about to.
My offer has been accepted on the boat in the picture here and I believe there are two of these bad boys hanging through the hawse pipes on this bow. I am headed to Amsterdam in a couple of weeks to experience a sea trail and survey that is not in my native language. That ought to be interesting. I will also be interested in getting a close look at these anchors.
Not a tippy-toe to the edge kind of guy, are you?

DANG that's a purdy boat. Dare to Dream
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Old 03-23-2016, 12:47 PM   #34
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"Danforths in my experience are handicapped by poor performance during pull direction changes (wind shifts)."

Operator problem.

Mr Ogg inventor of the Danforth in his book always suggests 2 or more anchors to solve this problem.

A 12 H stern anchor , hand set ,will solve the "problem" in under 2 min of effort.
How is this in any way considered an operator problem if two anchors are required in order to reliably work? It is an anchor problem.

Now the danforth has proven itself as a great anchor. True. But not reliably with big shifts.
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Old 03-23-2016, 01:07 PM   #35
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Klee wyck Bill,
Those anchors on the Libra are not the SHHP Posidonia anchors. The flukes on the anchors on the Libra are splayed out quite a bit kinda like the Forfjord whereas the outboard edge of the flukes are nearly parallel to the shank on the Posidonia. Not the same anchor.
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