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Old 06-05-2016, 10:20 PM   #61
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Originally Posted by Peter B View Post
So, overall...the catenary IS a really important factor in staying put I would say.
I would add that all-chain and more rode are the two best ways to increase catenary. There is, however, diminishing utility to rode and a point (where the force necessary to life the anchor end of the chain) where extra rode has no catenary value (although, apropos of a comment above, it will diminish jerk). I tried to calculate this years ago using both calculus and modeling. I think I got the answer right since both approaches gave the same result. As I recall, 7 to 1 was overkill, but I don't think the break point was a lot less (although a downward-slopping sea floor does argue for greater scope).
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Old 06-05-2016, 11:38 PM   #62
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PeterB,
I agree w your post #60.
But that's assuming the anchor will cease to pitch the shank down. And I see nothing that will bring that about. But if the anchor ceases to pitch the shank down the fluke will pitch upward and as soon as it's upward enough the anchor will (if given enough tension) break out.
But I see no force that would bring that about.

MYTravler,
Scope and chain are good for anchoring performance. I have never anchored in 30knots or more of wind w less than 4-1 scope. But even in 50 knots of wind I've not used more than 15' of chain. In winds above 40 I've always used an XYZ anchor.
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Old 06-05-2016, 11:50 PM   #63
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Makobuilders... If you put your hunk of studded chain about 10' up from the anchor it would probably be close to ideal. I wonder why you asked this question though because almost nobody here has a ground tackle settup that would retrieve such a rig. One would need a reel type winch.
Let's get back to a practical situation... anchor followed by a short leader of heavy studded followed by the rode. Very common with the commercial boats with reels. And if the studded is short (say 3 ft) then it would fit a lot of recreational boats as long as the windlass sits back on the bow.

So my question was more about attaching the nylon directly to that short, fat leader and dispensing with the typical 30+ ft of light chain.

I agree with you that the best weight is put into the anchor, perhaps to the extreme, but then you need some very heavy leader to keep the pull at the shank as horizontal as possible.

I did this on my little boat that I just sold. It worked fantastic in winds up to 30-35 knots, but I never had a chance to compare it side by side with a "normal" setup.
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Old 06-06-2016, 12:59 AM   #64
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Originally Posted by makobuilders View Post
Let's get back to a practical situation... anchor followed by a short leader of heavy studded followed by the rode. Very common with the commercial boats with reels. And if the studded is short (say 3 ft) then it would fit a lot of recreational boats as long as the windlass sits back on the bow.

So my question was more about attaching the nylon directly to that short, fat leader and dispensing with the typical 30+ ft of light chain.

I agree with you that the best weight is put into the anchor, perhaps to the extreme, but then you need some very heavy leader to keep the pull at the shank as horizontal as possible.

I did this on my little boat that I just sold. It worked fantastic in winds up to 30-35 knots, but I never had a chance to compare it side by side with a "normal" setup.
I still like to think of the anchoring gear as a unit. The sum of its components, with no one thing being the be all, and end all. So while, yes, it's nice to have an anchor that sets quickly, with minimal fuss and backing down, and that digs deeper with time and tension, I also like to think of it as mainly being that which locates the end of the rode on/in the bottom, but which is seldom called upon to take direct boat weight on it, because of the catenary in the rode.

So, in effect the weight of the chain is what anchors the boat, with the anchor just holding the end of it to straighten the whole shebang out. Kinda simplistic, I know, and Eric won't like the analogy, but that's just the way I think of it all...

However, I concede that when anchoring in the type of depths the folk up in Alaskan waters, and no doubt elsewhere, anchor, in waters often over 60 feet deep, then the combination rode fits right in there with the concept as well - with just the added element of the rope part of the rode to the unit.
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Old 06-06-2016, 06:51 AM   #65
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"So, in effect the weight of the chain is what anchors the boat, with the anchor just holding the end of it to straighten the whole shebang out. Kinda simplistic, I know, and Eric won't like the analogy, but that's just the way I think of it all..."

With this concept no boat with a rope rode could ever anchor as the rope is near weightless in water.

Since the Danforth was first used in military service with NO chain , what held?
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Old 06-06-2016, 08:07 AM   #66
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It's interesting how Danforth and Fortress both recommend only short sections of chain. The below from Danforth's website shows some heavy leader, although not quite the stud link we've been discussing.
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Old 06-06-2016, 08:24 AM   #67
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Quote:
Originally Posted by FF View Post
"So, in effect the weight of the chain is what anchors the boat, with the anchor just holding the end of it to straighten the whole shebang out. Kinda simplistic, I know, and Eric won't like the analogy, but that's just the way I think of it all..."

With this concept no boat with a rope rode could ever anchor as the rope is near weightless in water.

Since the Danforth was first used in military service with NO chain , what held?
Just the anchor, FF, and probably not very well...
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Old 06-06-2016, 11:03 AM   #68
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Makobuilders wrote;
"Let's get back to a practical situation... anchor followed by a short leader of heavy studded followed by the rode. Very common with the commercial boats with reels. And if the studded is short (say 3 ft) then it would fit a lot of recreational boats as long as the windlass sits back on the bow."

They (the fishermen in Alaska) do that very commonly. Frequently three differend sections of rode. Very heavy chain, heavy chain and then nylon line. Even some studded chain. Makes sense. Hold the shank down where the shank is. I followed their lead and used 3' of 3/8ths chain attached to the anchor, then 5/16" chain for about 8' and then about 5' of 1/4" chain followed by 400' of 5/8ths Brait line. On my 30' boat putting the heavy stuff 10 or 13' up the rode from the anchor would'nt have worked well hand pulling the chain so I stuck w the arrangement above. And I will add that the fishermen all use hydraulic reel winches.

The best way to mimic the fishermen and put the heavy part of the anchor rode where it belongs (as weight) to do the most good catenary wise and even just holding the shank down is to concentrate the weight (chain) where it does the most good. Chain weight up next to the bow of the boat holds the bow down whether or not the rode is deployed or not.

The point of catenary is to lower the attach point of the shank where the rode attaches so the anchor fluke has a good angle of attack. With a 10-1 scope angle of attack is assured. But in the usual anchorage less scope is very desirable or even necessary in Alaska (and probably elsewhere) but anchoring at 4 or 5-1 is the norm and shortening up when desirable. Lots of shortening up can be safely done as evidenced by Steve's (Panope) vids .. even 2-1.

But the point I was trying to make earlier in this thread is that once the fluke sets enough to develop some tension on the rode the anchor shank pitches down because the fluke and shank acts like a lever pitching the shank down. And w the shank down or on or even in the bottom catenary is not needed or at the least not very necessary. So if one sets long (5-1) and shortens up all will be well.

These tecniques of anchoring are already being done by many and is an easy method to adopt if not. Then most or at least half of the chain on one's rode can be despensed with. And for those that feel chain weight is golden use much heavier chain lower down on the rode. Kinda like the fishermen.
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Old 06-06-2016, 11:10 AM   #69
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It's interesting how Danforth and Fortress both recommend only short sections of chain. The below from Danforth's website shows some heavy leader, although not quite the stud link we've been discussing.
Do they recommend a "minimum" or a "maximum" amount?

Went to the only website I could find and the chain info and engineering data was a little sparse.....like non existent except for pre-packaged stuff suggestions.
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Old 06-06-2016, 11:29 AM   #70
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"So, in effect the weight of the chain is what anchors the boat, with the anchor just holding the end of it to straighten the whole shebang out. Kinda simplistic, I know, and Eric won't like the analogy, but that's just the way I think of it all..."

With this concept no boat with a rope rode could ever anchor as the rope is near weightless in water.

Since the Danforth was first used in military service with NO chain , what held?
Re FF's post using no chain is a bit of an extreme or exageration ... even I have never done that. But not too long ago small boats did'nt have anchor winches and everybody hand pulled their anchors. It was fairly common knowledge then what anchors performed best w minimal chain. All anchors vary in this regard. Some are needy and some do fairly well w little or perhaps no chain. The Dreadnought anchor (below) has a very long and heavy shank and I've heard more than once that it was designed to be used w/o chain. The anchor design is probably 100yrs old so how somebody would know that is odd at least. I've only used the anchor once and it set so fast no dragging was done or needed. Holding power is not high I'm sure but 20 or so fishermen in Craig Alaska use this anchor now. One said it "drags in 60 knot winter gales" but does OK in 50 knot summer gales. ???
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Old 06-07-2016, 06:10 AM   #71
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Running a landing craft up on a beach to land an assault was done with strong winches and ZERO chain with Danforths .

Think Normandy.

The day boat fish guys or head boat fish guys I know want the anchor to deploy and come back with no hassle.

They will anchor only as long as the fish are in that spot and then move on.

Weather its just weight dragging and a slow drift or the anchor catches is minor .

The scope is seldom over 2-1 (if that) and the boat is moved as the fish and tides vary.

IN port they tie up , not anchor .
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Old 06-07-2016, 07:42 AM   #72
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Once the chain come bar tight there is no more centenary effect.

As to boats picking up your anchor, sure it can happen but it's pretty rare. Except where you are with all the charters I guess.

The first boats in US waters were Indian canoes.
Saw high winds a week ago when anchored at Newcastle Island. Dragging sailboat indeed dislodged anchor on a large yacht creating quite a set of problems and damage.
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Old 06-07-2016, 07:56 AM   #73
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Do they recommend a "minimum" or a "maximum" amount?

Went to the only website I could find and the chain info and engineering data was a little sparse.....like non existent except for pre-packaged stuff suggestions.
Back in my trailer yachting days in NZ, when I did use a Danforth and mainly rope rode, the general rule always quoted, and recommended in the various books, was a length of reasonably heavy chain the length of the boat. Seemed to work well, and had a certain (weighted) logic about it.
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Old 06-07-2016, 08:07 AM   #74
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Back in my trailer yachting days in NZ, when I did use a Danforth and mainly rope rode, the general rule always quoted, and recommended in the various books, was a length of reasonably heavy chain the length of the boat. Seemed to work well, and had a certain (weighted) logic about it.
True...for 50 plus years I have hear lots of combination rode numbers....yet I am not sure that I have really ever seen any science in those numbers or why some pick numbers with more or less chain.

So far the only one I have heard that used a specific number that had any correlation was a boat length of chain and that's appears to be to keep line out of the props if current and wind twist you in a funny lay....not so much for holding or chafe.
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Old 06-07-2016, 08:35 AM   #75
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True...for 50 plus years I have hear lots of combination rode numbers....yet I am not sure that I have really ever seen any science in those numbers or why some pick numbers with more or less chain.

So far the only one I have heard that used a specific number that had any correlation was a boat length of chain and that's appears to be to keep line out of the props if current and wind twist you in a funny lay....not so much for holding or chafe.
Yes, that and the fact it automatically limits the length to something practical to stow and handle, based on the size of the vessel.
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Old 06-07-2016, 08:47 AM   #76
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Yes, that and the fact it automatically limits the length to something practical to stow and handle, based on the size of the vessel.
True again...but look at all the other seemingly random chain length suggestions and the previous packaged ground tackle...often just a few feet of chain, plastic covered, etc....

My point with the chart posted for danforths, where did those numbers come from? Science or a wag?
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Old 06-07-2016, 08:57 AM   #77
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Saw high winds a week ago when anchored at Newcastle Island. Dragging sailboat indeed dislodged anchor on a large yacht creating quite a set of problems and damage.
I was talking about as a boat maneuvers past your bow while you are at anchor.

In your example did the boat that the other boat got fouled on have line or chain as rode? Could you tell for a fact that if it did or would have had all chain rode the dragging boat would not have fouled it's rode/anchor because of that?
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Old 06-07-2016, 09:02 AM   #78
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As I recall this book does one of the best jobs I've seen explaining the forces that act on an anchor and rode that I've seen.

https://www.amazon.com/Complete-Anch.../dp/0071475087
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Old 06-07-2016, 11:14 AM   #79
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A maximum amount of chain is obvious ... all chain.

Does Chapman still recomend "a few feet of chain"?

The biggest variable in anchoring is still the bottom.


Bill,
That handbook ... "Stay Put on Any Bottom in Any Weather" says volumes about the credibility of the contents. Start off w the impossible.
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Old 06-07-2016, 12:03 PM   #80
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Bill,
That handbook ... "Stay Put on Any Bottom in Any Weather" says volumes about the credibility of the contents. Start off w the impossible.
Unless of course it's true.
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