How Much Chain Rode

Peter B said:

So, overall...the catenary IS a really important factor in staying put I would say.

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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).

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.

Nomad Willy said:

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.

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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.

makobuilders said:

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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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.

"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?

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.

FF said:

"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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Just the anchor, FF, and probably not very well...

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.

makobuilders said:

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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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.

FF said:

"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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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. ???

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 .

Capt.Bill11 said:

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.

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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.

psneeld said:

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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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.

Peter B said:

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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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.

psneeld said:

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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Yes, that and the fact it automatically limits the length to something practical to stow and handle, based on the size of the vessel.

Peter B said:

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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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?

sunchaser said:

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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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?

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-Anchoring-Handbook-Bottom-Weather/dp/0071475087

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.

Nomad Willy said:

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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Unless of course it's true.

Bill,
Hurrycane in Chesepeke Bay?

I obtained a copy of an old book called the complete book of anchoring and mooring by a guy named Hinz

The Complete Book of Anchoring and Mooring: Earl R. Hinz, Richard R. Rhodes: 9780870334528: Amazon.com: Books

Excellent book for calculating loads due to wind, shear, surge, etc. In it he recommends half the anchor weight in chain, which generally works out to about a boat length, perhaps slightly less.

However, back to the question about Danforths and Fortresses, I've heard something along the lines that the shank needs to be lifted in order for it to set properly, so they do not recommend full chain.

PMako,
I think that's the book Marin kept talking about trying to drum up support for all chain. So Hinz recomends not much chain just like Chapman.
The problem w most here is that they have no flexibility. They have one rode rigged up ready to deploy and the spare a PITA to get out and deploy. Some have two anchors and rodes ready to go on the bow pulpit. So most trawler guys need an anchor and rode good enough for a 50 knot blow.
If I had a bigger boat w a single rode and anchor I'd likely have a big to very big anchor and 25% of rode in chain. And a quickly attachable nylon section to extend the whole thing out to 6 or 700'.



Does Hinz say anything about rigging and operating (winch wise) a combination rode other than the usual combination gypsy?

So the experts are'nt talking all chain ... sure is popular here.

Articulated shank (Danforth and Fortress) need to lift their shank to .... Never heard that before. I think Steve (Panope) used all chain and don't recall there being a setting problem. Don't see how that would aid setting much less be necessary to bring it about. Dono

If you can estimate the loads from wind, waves, swell, currents etc. including dynamics resulting from gusts ... And if you can assure that the anchor will take those under the given conditions at the ground - the rest is simple math solving the differential equation of the catenary.
Will try to post a small excel sheet end of the week when back from business (sh..., still have to work to finance my boating life)



best regards / med venlig hilsen
Wadden

Capt.Bill11 said:

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-Anchoring-Handbook-Bottom-Weather/dp/0071475087

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You are right about that. And frankly book learning seems to be superior to the experience learning for most on this thread, to which my reaction in general is

To the point I almost wonder if several of these posters have ever anchored overnight, let alone multiple nights..

George,
Book learning and experience are both very important.
The way you talked about it makes everybody think they've been attacked.
Lots of experience anchoring in nice weather dosn't teach much and anybody can pop off a book of opinions w just a little bit more trouble than posting on TF.
Criticizing everybody isn't of much value either.

Wadden,
My experience reading about wind forces produces results all over the map.

I've thought of tethering a boat in a steady wind w an accurate tension meter or scale.

Measuring frontal area is useless because there are so many little things that increase drag. How much drag is that cleat or windshield wiper. Sounds silly but there are hundreds or possibly thousands of little things that cause drag. Some things just can't be made into numbers. And approximations could be 75% (or worse) off of reality. And then there's the bottom. The sea floor. The biggest variable. By far.

I haven't seen any mention of Forfjord Safety anchors. My dad was a big fan of these and used them often on his salmon trollers. There is one boat on my dock in LaConner that has one on the bow. I looked at them on the Kolstrand site and they are very expensive. I think they are more often encountered on commercial boats.

Steve (Panope) tested his own Forfjord and it did poorly I belive.

I've always thought of them as a cross between a Danforth and a Navy anchor. And I think at times they probably only burry one fluke and pretend they are a Kedge. I bought one, tried to set it .. it would'nt so I deployed my trusty 13lb Danforth and it set right away.

Yes the fishermen in Alaska almost worship the Forfjord. The #2 anchor choice among the fishermen is the Claw and the 3rd is the Dreadnought. I personally think the Claw is better than the other two but this post is rather subjective. Now and then one can find a Forfjord supporter but not often.

78,
There was a thread on the Forfjord in the recent past. Don't remember the essence of what was said. Check it out.
Looked it up. It's on page 2 toward the top and titled "Forfjord" .. went 4 pages.

I probably posted that in the wrong thread, just sort of popped into my head while reading this one! I think dad like it for varied bottom conditions and of course weight is not such a concern on a fish boat so he could go heavy.