Dare I Say Another Anchor Article

Regarding commercial shipping and anchoring. There is usually a queue of ships waiting to load coal at the Newcastle NSW loader facility. These ships, perhaps as many as 15-20, habitually anchor off the coast while waiting to load, which suggests they really do sometimes rely on anchoring. Though I have read of some just drifting, and uncontactable by radio by nervous passing pleasure boats.
It would be nice if all anchor makers were respectful of their peers, I`m sure they all set out to produce an effective anchor.

BandB said:

I will say this. I strongly dislike companies or individuals creating additional websites to promote their product without full disclosure of the connection. It's done constantly and in poor form I believe.

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Amen to that!

BruceK,
I may be the only one here on the forum that has a ship style or type of anchor. I've only used it once and it set so fast it was set before I started setting it. I lowered the anchor, chain and line, threw out slack as we backed down and when I made the rode fast on the cleat the line went very tight immediately w/o any dragging. I gave it 1400rpm for a minute or so detecting no movement sighting the shore. Don't remember any wind that night and it was easy to retrieve in the am.

I'm replacing the pin that the shank attaches to in a few days and should try it again fairly soon. The pin is a 3/4" bolt. The original was a pin w a round head much like a rivet. With it's heavy shank it rests nicely on the bow roller but I don't like the obstruction of the view fwd.

Eric
Do you mean the "Navy" anchor?

Eric and Ted, is that a "Dreadnought"?
Googling it, I came across an article by Aussie Jonathan Neeves, seems a knowledgeable guy, writes for a number of magazines. I`ve read his stuff before.

Hi Bruce,
Not a Dreadnought, it's a Navy.
Found a better picture, different angle.

Ted

Since you ask ...
Ted no not Navy. Dreadnought. At least that's what the fishermen in Craig Alaska call them. Pic 1 is the business end in detail. Pic 2 is the Dreadnought on a typical well maintained fish boat. Probably about 20 boats in Craig have Dreadnoughts. One skipper says they hold during the 50 knot summer gales but drag in the 60 knot winter gales. That from the owner of Rauma.

Re the Navy anchor I don't recall any in Craig Alaska. Pic 3 & 4. Gray Pelican goes to Alaska every year (from LaConner WA for the whole summer and has for about a decade that I know about. This Navy anchor has been on his bow for at least ten years. Grey Pelican is 50'.
pic #5. While in Seattle I took this pic of an old wood boat w a Navy anchor. Looks like the winch is holding the anchor and not the chain stopper at the top of the hawspipe.

Pic 6 & 7. Pacific Queen found my camera in Petersburg AK w a Navy anchor. Pic 7 shows how small the anchor is compared to the overall size of the boat. I offer this re what somebody said about how small some anchors look on ships and larger craft.

On Grey Pelican and the Pacific Queen there is only one anchor so I'm sure it performs well on all bottom types. Unlike most or all of our "high performance" yacht anchors.

So is there a "best" anchor among all of our yacht anchors that has no flaws like these old dogs? The Navy anchor in pic #5 is very big but the others are not overly large. And significantly I submit that Pelican and Queen don't drag overmuch and are considered good anchors by their owners and operators.

The last pic is my Dreadnought on Willy's bow entering the north end of the Broughton Group.

The Dreadnought and Navy both use appendages on the back of the anchor that drag an edge on the bottom. This drag transfers force (lever like) on the fluke tips that augments their considerable weight and insures penetration. They don't normally penetrate more than 6 to 10" depending on size. These anchors Have a standard throat angle of about 40 degrees .. More than Danforths and other yacht type anchors.

Hi Eric,

I just took another picture.
It doesn't seem to have the shape of the dreadnought or the
long shaft. Reportedly 350 lbs.
Have another look, more like pic #4?

Ted

psneeld said:

Yep...because ...I don't think the ships really carry ground tackle to anchor in conditions that smaller vessels experience IN PROPORTION.

If they do experience proportional conditions, they have the crew to motor against the forces or get underway and head for sea.

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Bingo!

I recently purchased an FX-23 (thanks Parks!) to use as rear anchor in an extremely soft-mud-bottom. FX-23 anchor is rated for boats larger than our 34' Tolly tri cabin; but, in the mud-bottom, wind, and current conditions where we often anchor - I feel that's what is needed.. Last weekend was our first trial/test. I plan to test the set, hold, and stay capabilities of this anchor all year long and with differing chain/line percentages as well as scope length configurations when we're in applicable muddy bottom conditions. I am keeping log on results and may post all (or a condensed version of) our FX-23 anchoring experiences after some time.

So... back to quoted statement in bold (see above) - Again I say, BINGO!!

psneeld conjecture is spot-on... IMHO!

Ted,
The Dread has a long round shank and as you know the Navy has a short square shank. The rest of the Dread isn't much different but it's design is webed so the arms that are at the base of the flukes are lighter. So it's not quite as dense as the Navy. Very much the same though.

Eric

Agreed.
The shank on this one is 37" long to the head pivot,
by 4" wide by 1 1/2" thick.
It'll need a derrick to pick it up. lol

Ted

psneeld said:

Yep...because ...I don't think the ships really carry ground tackle to anchor in conditions that smaller vessels experience IN PROPORTION.

If they do experience proportional conditions, they have the crew to motor against the forces or get underway and head for sea.

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Art said:

Bingo!

I recently purchased an FX-23 (thanks Parks!) to use as rear anchor in an extremely soft-mud-bottom. FX-23 anchor is rated for boats larger than our 34' Tolly tri cabin; but, in the mud-bottom, wind, and current conditions where we often anchor - I feel that's what is needed.. Last weekend was our first trial/test. I plan to test the set, hold, and stay capabilities of this anchor all year long and with differing chain/line percentages as well as scope length configurations when we're in applicable muddy bottom conditions. I am keeping log on results and may post all (or a condensed version of) our FX-23 anchoring experiences after some time.

So... back to quoted statement in bold (see above) - Again I say, BINGO!!

psneeld conjecture is spot-on... IMHO!

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I'm not convinced about the "IN PROPORTION" part of this comment. The effect of wind and current is already much higher on larger boats/ships since it's impacting a much larger surface area. In general, the surface area of a boat will increase as the square of its length. So a boat double the size will experience four times the load from wind and current. A 1000 foot boat is 20 times longer than a 50 foot boat and will experience loads that are 400 times greater from wind and current. It seems to me that you're double counting if you try to claim the conditions also need to be scaled up.

This is borne out by the formula quoted by Insequent in post #40. The "equipment number" has in its formula the displacement raised to power 3/2. That's basically saying it's proportional to the surface area of the boat. The mass (displacement) goes up as the 3rd power and the surface area as the 2nd power of length. That means that they are sizing equipment based on surface area (the rest of the formula is all about surface area too.)

I know this is starting to get rather mathematical - but let's face it - this is all about fluid flow around a solid object - so it's hard to avoid the math.

Richard

Assuming steady forces...when are forces in anchoring steady?


In 30 knots of wind....most small boats I see are dancing all over the place.


A ship is hardly seen to be movng at all.


I have always said...I would rather be in a calm anchorage with 50 knots of wind than an exposed one in 30. I am convinced well set ground tackle is more prone to dragging from dynamic forces than steady.


Also, the same drag formulas for calculating hull speed are probably similar for current pressure on an anchored vessel...I don't agree with your numbers saying that just because surface area goes up so does the force proportionally. ...things like prismatic coefficient play in.


How does length play in anchoring other than surface friction induced drag?


Math is great..only when you use the right numbers and the right assumptions.


Wind certainly plays a big role...thus why I hardly ever see big ships ever ride out a blow without engines online at th ready.

psneeld said:

Assuming steady forces...when are forces in anchoring steady?


In 30 knots of wind....most small boats I see are dancing all over the place.


A ship is hardly seen to be movng at all.


I have always said...I would rather be in a calm anchorage with 50 knots of wind than an exposed one in 30. I am convinced well set ground tackle is more prone to dragging from dynamic forces than steady.


Also, the same drag formulas for calculating hull speed are probably similar for current pressure on an anchored vessel...I don't agree with your numbers saying that just because surface area goes up so does the force proportionally. ...things like prismatic coefficient play in.


How does length play in anchoring other than surface friction induced drag?


Math is great..only when you use the right numbers and the right assumptions.


Wind certainly plays a big role...thus why I hardly ever see big ships ever ride out a blow without engines online at th ready.

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Your point about dynamic forces is a good one. My comments were restricted to the constant forces of wind and current. Presumably you are saying that waves create movement that is more likely to unset an anchor and that this movement doesn't scale up in the same way. I buy that.

I don't agree with your comments on the surface area though. The prismatic coefficient is just that - a constant. It models the differences from one hull shape to another. It doesn't model the proportional effect of increase in size. I stand by the idea that for wind and current the forces go up fundamentally in proportion to the surface area presented to the wind or current.

Richard

Well I'd post a picture of a Rocna and provide a drum roll but I don't have a picture of a Rocna and everyone knows what they look like. And who needs a drum roll w Oliver on board?

I just scoped out the very few commitments and here are the results:

1. Rocna 7 votes
2. Manson Supreme 2
3. Excel 1
4. Fortress 1

I thought there would be an avalanche of very positive votes w most talking up their favorite. Total opposite. I had to read between the lines and in Marin's case just assume. I voted in this post and was having a lot of trouble deciding. Finally decided we had to include the roll bars and then couldn't decide MS or SARCA. If I had experience w the SARCA I likely would have gone there. I have claimed the SARCA to be the best in the past so I'm obviously on the fence.

But I don't think this is very representative of reality. Many more different anchors would be present if so. But I'm sure Rocna would come out most frequently chosen.

Many to most would agree so perhaps the discussion about ship anchoring presents the best opportunity to do some learning.

Wifey B: I'll vote....the Hydrobubble....

The Wasi or Bugel?

Or if you don't like those, how about the Bulwagga?

You dudes are missing so many anchors.....:lol:

Northern Spy said:

Sigh. There are two different methods of anchoring. Drag enbedment and tension anchoring.

Theoretically, a drag enbedment anchor merely holds the end of a centenary chain. Long enough chain, no anchor required.

A tension anchor requires the use of a well placed anchor with a cable or rope rode.

They use entirely different physics.

Eric, the short scope ratio anchors you prefer use tension. The rest of the big boats with bohunking metric f-tons of chain can get away with a chain catenary and an anchor at the end.

I have pulled up ships moorings that have no anchor, just a lot of chain which provides a lot of drag in the mud.

Indeed, I know of a sub that anchored successfully with chain only, as the anchor was cut off, as it was banging on the ballast tanks like a gong.

Eric, please look this up. Your arguments have merit, but only when your comparisons are the same.

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I've been thinking about that.
Spy you're one of the best thinkers onboard and I definitely do pay attention to your posts.

Certainly a chain could be an anchor. And chain seems to help anchoring.

With most rode configurations it has been said that in a strong blow all the catenary comes out and the chain is lifted off the bottom. The chain would need to become straight to loose all the catenary. I think it was Peter Smith that said that so perhaps I should discard it. I discount it but don't discard it. If it's true (I doubt it) and the anchor holds then the chain actually dosn't help holding the boat.

It may even, to a small degree help pull the anchor out. I say that because the very considerable weight of the chain straight or nearly so adds to the pull on the anchor (and the boat). Just like if you tied a line between two solid objects, measured the tension on both ends, then hung a blob of chain in the middle the tension at the ends would go up. So it must be w anchor rodes.

That aside, the chain (w moderate loads) does clearly aid catenary and hence (it would seem) anchor performance or effectiveness. But the anchor is'nt anywhere near it's breakout tension and dosn't need (can't use) the benefit from catenary.

So it still seems to me that the only time chain helps performance of a rode is during the setting of the anchor. Holding the shank up clearly dosn't help set an anchor, especially at a steep angle (short scope). But if one's anchor sets smartly and dependably even that is not needed.

So Spy, that is how I view the issue of chain on a boat's rode. With a weak or very small anchor chain could possibly be an aid to holding power but most all of us don't use Kedges or other low performance anchors.

I'm still w Chapman on this "a few feet of chain". Often I feel I must be wrong though as everybody's against me on the issue of chain.

Fortress Anchors said:

Additionally, I think he would be farther ahead to take the approach "all anchors are great, and mine is even better," rather than spend time disparaging other products.

Regards,
Brian

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Brian, that is what I want to hear a manufacturer say, good to you for that!

It's not like one anchor sucks and another one is great. There is decades to centuries of successful history with some of these designs. If they were so bad people would have quit using them a long time ago.

Anchoring debates are often based on using static models to make an argument...such as the boat and anchor BOTH being stationary objects with no momentum....and the ability to exert a static force.


Good luck convincing anyone with practical experience...and why do so many people disagree with anchoring test results based on limited test parameters?

psneeld said:

Anchoring debates are often based on using static models to make an argument...such as the boat and anchor BOTH being stationary objects with no momentum....and the ability to exert a static force.


Good luck convincing anyone with practical experience...and why do so many people disagree with anchoring test results based on limited test parameters?

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That's not what I was saying. I happen to agree with you about the dynamic forces. I was talking about how wind/current forces scale up with size of vessel.

I'm certainly not disagreeing with any anchor test results.

Never mind...

Richard

Britannia said:

That's not what I was saying. I happen to agree with you about the dynamic forces. I was talking about how wind/current forces scale up with size of vessel.

I'm certainly not disagreeing with any anchor test results.

Never mind...

Richard

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Your premise before included using length for a vessel anchored at the bow...

I have no idea how the various shapes of large vessels compare to little ones and how forces affect them. But my guess is many large ships may actually have a smaller proportional head on profile (drag) than the average cruiser including sailboats that have a lot of drag from the rigging. Any available data or is someone gonna run dimensional calculations?

What is the relationship between dynamic and static forces?

Sorry to question your "math" but as I posted...what good is it if others don't believe the premise?

There is a thread about photos of anchoring, in various anchorages with various anchors from different boats in the Med, on CF,Photos of Anchors Setting - Cruisers & Sailing Forums. The thread was started as a result of the many My Anchor is Better Than Your anchor "conversations."

The photos are mostly from one couple but others are adding photos. The photos are taken by people diving in the anchorage to see the how the anchors have set. Often captains technique used to when anchoring has been seen and mentioned along with the photo(s) in question.

Some lessons I have taken from that thread:

• Many people do not properly set their anchor.
• A chain rode and an unset anchor will hold a boat in conditions that I would not have expected.
• A chain rode on the bottom helps hold the boat in place.
• Some anchors are much better anchors than others.
• Bad anchoring technique and/or inadequate anchor and anchor rode is not noticed until conditions pass a given point and this point is not seen by many boaters. They think their anchor and anchor rode is great simply because it is never really tested.

Later,
Dan

Regarding the anchoring of ships, Rick Boggs just sent me this link to a document which defines how anchor and chain size is to be determined based on the formula characteristics of the ship, how the anchor is to be set (note that they say the pull of the chain or cable on the anchor should be horizontal), and a whole bunch of other definitions and requirements.

http://www.iacs.org.uk/document/public/Publications/Unified_requirements/PDF/UR_A_pdf148.PDF

Re post #77, fourth paragraph,


"It may even, to a small degree help pull the anchor out. I say that because the very considerable weight of the chain straight or nearly so adds to the pull on the anchor (and the boat). Just like if you tied a line between two solid objects, measured the tension on both ends, then hung a blob of chain in the middle the tension at the ends would go up. So it must be w anchor rodes"

The notion that the weight of chain on a rode would increase tension on the anchor and help dislodge it is not right. I figured it out on my way to Starbucks. The added weight would pull the boat up a bit and equalize the tension that would be porportional to the drag of the wind or/and current. So I was out of my tree on that one.
Also unless there was enough wind to straighten out the line and chain the catenary would exist in stronger winds ... depending on how much chain weight was in the rode and where it was in the rode. But unless the anchor was on the verge of breaking out the extra catenary wouldn't do any good.

But my idea about chain weight degrading anchor performance was wrong.

RickB,

Please come back...

Dannc wrote;

"A chain rode on the bottom helps hold the boat in place"

I don't think so. You're thinking that the tension on the rode will be felt along the chain and the links will act like miniature anchors and help hold the boat. It won't. The chain will to some small degree relieve the anchor of the same amount of load but it's the anchor holding the boat .. not the chain. Only if the anchor was draging or on the brink of dragging would that be true.

Northern Spy said:

RickB,

Please come back...

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The most sensible post in this thread!

manyboats said:

Dannc wrote;

"A chain rode on the bottom helps hold the boat in place"

I don't think so. You're thinking that the tension on the rode will be felt along the chain and the links will act like miniature anchors and help hold the boat. It won't. The chain will to some small degree relieve the anchor of the same amount of load but it's the anchor holding the boat .. not the chain. Only if the anchor was draging or on the brink of dragging would that be true.

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Eric I find it funny you're stating these things like facts. The even funnier part is that you have about 5' of chain in your rode. So you know all about chain rodes.

Dannc wrote;

"A chain rode on the bottom helps hold the boat in place"

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Eric wrote; I don't think so.

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I think it's pretty obvious that the chain lying on the bottom keeps the boat in place until such time as the pressure applied to the boat by wind and/or current lifts the chain off the bottom.

Weight is weight. It doesn't matter if it's a length of chain or an anchor or a big rock. Until that weight is moved, it will hold whatever is attached to it in place.

The photo below was taken on a day when we happened to use our trip line and float. The length of the float line was adjusted to account for the tide range, but otherwise it had no other slack in it. So it floated more or less directly above the anchor.

We always use a scope of 5:1 to 7:1. And we deploy our anchor by lowering it as we are drifting back, thus paying out the chain, and then we set the anchor using the boat. Once we've stopped backing against the rode the boat moves forward as the chain sags back onto the bottom.

The place the photo was taken is a small bay in which the current changes almost continuously. So the boat never just sits in one place unless there's enough wind to make it do that. The end result is the boat is always moving around, sometimes describing a complete circle over time.

And guess what the boat was circling on this day. Not the anchor; the boat never got anywhere near the trip line float. It circled the spot on the bottom where the chain touched down from the pulpit.

Granted, the force applied to the boat was not great. So the weight of the chain was sufficient to keep the boat in the same place more or less. The anchor, in this particular instance and all the other instances like it, played no role whatsoever in keeping the boat in place because the "strain" on the rode never overcame the weight of the chain lying on the bottom so a good portion of the chain never moved and thus never transmitted the pull of the boat to the anchor.

If the wind had come up, absolutely the anchor would have begun to play a role. The chain would have been pulled on and picked up and if the wind was strong enough eventually the pull of the boat would have been transmitted all the way down to the anchor.

But to say the weight of the chain doesn't keep the boat in place is to contradict some fairly proven principles, like gravity.

Marin said:

I think it's pretty obvious that the chain lying on the bottom keeps the boat in place until such time as the pressure on the boat lifts the chain off the bottom.

Weight is weight. It doesn't matter if it's a length of chain or an anchor or a big rock. Until that weight is moved, it will hold whatever is attached to it in place.

The photo below was taken on a day when we happened to use our trip line and float. The length of the float line was adjusted to account for the tide range, but otherwise it had no other slack in it. So it floated more or less directly above the anchor.

We always use a scope of 5:1 to 7:1. And we deploy our anchor by lowering it as we are drifting back, thus paying out the chain, and then we set the anchor using the boat. Once we've stopped backing against the rode the boat moves forward as the chain sags back onto the bottom.

The place the photo was taken is a small bay in which the current changes almost continuously. So the boat never just sits in one place unless there's enough wind to make it do that. The end result is the boat is always moving around, sometimes describing a complete circle over time.

And guess what the boat was circling on this day. Not the anchor; the boat never got anywhere near the trip line float. It circled the spot on the bottom where the chain touched down from the pulpit.

Granted, the force applied to the boat was not great. So the weight of the chain was sufficient to keep the boat in the same place more or less. The anchor, in this particular instance and all the other instances like it, played no role whatsoever in keeping the boat in place because the "strain" on the rode never overcame the weight of the chain lying on the bottom so a good portion of the chain never moved and thus never transmitted the pull of the boat to the anchor.

If the wind had come up, absolutely the anchor would have begun to play a role. The chain would have been pulled on and picked up and if the wind was strong enough eventually the pull of the boat would be transmitted all the way down to the anchor.

But to say the weight of the chain doesn't keep the boat in place is to contradict some fairly proven principles, like gravity.

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We do the same thing. Try to reverse with enough power to set the anchor and pull all the catenary out of the chain.