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3 hours ago, Max Rockatansky said:

My experience with Fortress is very good, but it has the same weaknesses inherent in any Danforth design: poor set in any weed, and dismal reversal/reset regardless of bottom type 

So far, experience has taught me that ‘carry different anchors for different bottoms’ is good advice

My experience exactly. Reset is horrible, especially when it's a moderate or slow reset, so the rode drags over the anchor and fouls. 

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I think saw Q made the place a bit un-friendly. Who needs that?

When I started the anchor videos, it was just the underwater stuff and on-screen text.  Right away the accusations started flying that I was working for a particular anchor manufacturer.  Understandab

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10 hours ago, SASSAFRASS said:

Hmmm... A test setup and paid for by Fortress and performed by them and surprise they are the bestest.......Just a tiny bit suspect.

Yes it's wise to be skeptical. 

I did a bit of research before I posted.  Look up "Chesapeake bay soft mud anchor test". 

The tests were well conducted IMO and quite thorough, conducted by a well equipped University of Maryland test vessel and crew. All the results were available real time to a bunch of independents who witnessed the tests over 4 days. The raw data results from each test have been published. ( found and attached pdf )

It was a safe bet for fortress to sponsor because they are the results you'd expect. Flukes at 90 degrees to the mud generally engages more seabed.

My interest in this test specifically is that the  Danforth performed identically for the same fluke angle, which is what I expected from anchor theory and if the Danforths flukes were angled at 45 degrees it would match the fortress set at 45 too. There's no magic in the design. 

The take from this is that overall the best holding mud anchors for smaller vessels are Danforth pattern anchors. 

 

 

 

 

Chesapeak Bay soft mud anchor test.pdf

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14 hours ago, MikeJohns said:

The take from this is that overall the best holding mud anchors for smaller vessels are Danforth pattern anchors. 

Chesapeak Bay soft mud anchor test.pdf

Or, more correctly, the anchor with the most fluke surface are will win in soft mud, irrespective of weight or almost any other considerations.  If you have a windlass so don't care, just change to a larger anchor.

Still, if a change in wind direction is a real possibility, one of the other designs is a much safer bet as the Danforth pattern is unlikely to reset after a significant wind direction change.

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2 hours ago, Salazar said:

Or, more correctly, the anchor with the most fluke surface are will win in soft mud, irrespective of weight or almost any other considerations.....

i believe that depth of penetration is as important (or more) than fluke size.

Steve

 

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What I think happened is not so much that the chain fouled, but that the big flukes kind of have lift more or less and the damn thing skated along without re-engaging.

My recent soft mud experience is with my Manson Supreme. Dog River, AL. Locals told me to expect to drag. I guess we got 30s, and the winds did reverse, but I stayed put. This is the instance of clay well up the chain I mentioned earlier. At high tide I had 7:1 out. Chain is 3/8”, boat a 40’ 2d-gen Catana (Crowther) loaded up to 18.5Klb (sigh). Technique is to ease in initially, then gradually back, both engines to 2500rpm

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10 hours ago, Salazar said:

Or, more correctly, the anchor with the most fluke surface are will win in soft mud, irrespective of weight or almost any other considerations.  If you have a windlass so don't care, just change to a larger anchor.

Still, if a change in wind direction is a real possibility, one of the other designs is a much safer bet as the Danforth pattern is unlikely to reset after a significant wind direction change. 

Sure but there are several uses for anchors.

The Danforth patterns for their size have a staggering performance in mud when they set deep. Testing shows it's far more than I thought.

Given their holding power for size in mud they make a good kedge, or recovery anchor. So now I'm re-thinking what anchors I'm going to have aboard routinely when cruising.   I might even modify a Danforth for an optional fluke angle.

I agree that for a main anchor there are more reliable setters with moderate holding that you'd trust more reliably to set and reset. 

On a 40 ton boat I use a Naval Stockless as the main anchor !

 

 

 

 

 

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19 hours ago, Max Rockatansky said:

Thanks as always. I don’t recall whether you have tested a Brittany style anchor?

I have not yet tested a Brittany anchor, Max.  

I'd be happy to, but they are not common in these parts of the world.

Steve

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6 minutes ago, Panope said:

I have not yet tested a Brittany anchor, Max.  

I'd be happy to, but they are not common in these parts of the world.

Steve

As it happens... I have a 15kg in storage... I’m presently in the next state away and prepping for Zeta but I’ll try to remember to get it. I’ll holla when I do

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10 minutes ago, Max Rockatansky said:

As it happens... I have a 15kg in storage... I’m presently in the next state away and prepping for Zeta but I’ll try to remember to get it. I’ll holla when I do

Great!

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On 10/3/2020 at 5:01 PM, weightless said:

Most of the arguments against kellets working in bad conditions that I've seen assume a static world. If the wind is swirling then a boat can get moving very quickly and then come up with a big shock load particularly if the boat has gotten out of alignment with the wind.. If there's a chop, sea or surge then there will be shock loads. A kellet could start acting to slow the boat down before a snubber and is potentially a better shock absorbing device. Are they really helpful? IME, yeah, sometimes, but for sure the details matter.

 

On 10/21/2020 at 8:00 AM, Panope said:

Keep in mind that I use 3/8" all chain (very heavy).  Catenary will NEVER be COMPLETELY eliminated.

A heavy, steady wind is a static condition. However a gusty wind or sea state is very dynamic. When considering the catenary from either the chain or a kellet, you need to think about the energy absorbed. Waves or a gust hits, the boat surges backwards, reducing the catenary until the backwards surge is stopped. How much energy can be absorbed by the catenary? Some people intuit that since it takes an infinite pull to get the rode truly straight, that the energy absorbed will also be infinite or at least large. This is incorrect. The energy absorbed is only that required to lift the chain or kellet from its static position to an inline position between anchor and roller. This is not very much, relative to a 30,000 lb boat moving astern at 3 knots. 20 lb kellet lifted 30 ft off the seabed is 600 ft lbs. A 30,000 lb boat at 3 knots is 12,000 ft lbs. The kellet isn't useless, but not very useful either. 

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I get a lot of people asking me to conduct testing at scopes longer than my typical 3.5 to 1.  I mention my heavy, all chain rode in deep water to remind them that if they are using rope rode, my 3.5 to 1 will be equivalent to some longer scope (in terms of angle of pull on the anchor) during my setting and my higher power pulls.  I roughly guess that 5 to 1 might be sorta apples to apples.

 

Can anyone do the (static) catenary math for 105 feet of 3/8" BBB in water?  I'd love to know the angle of pull on the anchor at 680 lbs of pull (Panope's max reverse thrust).

 

I agree with DDW's and Olaf's posts above, and I will add that in addition to the WEIGHT of the chain/kellet, one should also consider the chain/kellet INERTIA (in a surge, the chain must be accelerated upward).

 

Additionally, we should think about the hydrodynamic drag of the chain as it is pulled upward through the water.  At midspan, the upward velocity of the chain will be significant (during a surge) and the resulting drag will absorb some of the boat's energy.

 

I have fused (welded) the links of a section of 3/8" BBB and added midspan "feathers" so that when released in water, the specimen would freefall horizontally.  I timed this drop in about 20 feet of water.  I'll have to dig up the data.  I remember being amazed at how quickly (almost instantly) the chain reached terminal velocity.

 

 js8828h.jpg

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Thanks Mike

So...

A rode with zero catenary (like all rope) at 5 to 1 scope would have an angle of pull of 11.5 degrees above horizontal.  If we throw in some chain (amount will vary boat to boat), it could be very close to 8 degrees (the value of all chain at 3.5 to 1).

I figure that for my boat, the 680 lbs. of pull is roughly equal to 40 or 50 knots of wind.

In other words, in winds up to a fresh gale, a heavy all chain rode in 30 ft depth (26 + 4 foot bow roller) at 3.5 to 1 scope, will have similar angle of pull at the anchor as a (mostly) rope rode of 5 to 1 scope (depth not important).

The above does not consider surge.  I assume that a mostly nylon rode will have better surge energy absorbing capability than the all chain rode.

Steve

 

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5 hours ago, Panope said:

The above does not consider surge.  I assume that a mostly nylon rode will have better surge energy absorbing capability than the all chain rode.

That raises an interesting dilemma.

Suppose that in the same depth, you have enough chain for a 5:1 all-chain scope, but also two spare rodes of the same length: one chain and one nylon..  And that your swing room is limited to 10:1.

So, having reached a zero degree pull angle at 5:1 scope, what's the best material for the second half of the anchor rode?  Continue with chain, or use stretchy nylon for surge absorbtion?

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16 minutes ago, Jim in Halifax said:

Most folks using an all-chain rode ensure they have a nylon bridle between the chain and the bow. Of course, more is often better.

I was talking about a lot more than a bridle,

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Might be in the other anchor thread but Zonker posted a test I think by PS showing load reduction based on line snubber length, type and size.  It's well worth a look, something like 60% reductions for some of the setups.

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When I tested the 2.5 pound Mantus Dinghy anchor with Panope (15K lb.), I used an ALL 1/4" nylon rode.

Panope was drifting broadside to the wind at 1/2 knot during the set.

Watching the rode slowly come up tight was fascinating.  It took several minutes for the boat to straiten out as the rode stretched ever longer.  It was like watching in super slow motion.  That poor little 1/4" line seemed as tight as a banjo string.

I am certain that if a non-stretch rode was used, the peak load would have exceeded the holding power of the anchor.

For the record, I normally anchor with all chain and almost never set up a snubber because a somewhat oversized, modern anchor has much reserve holding power. 

Of course, if the wind really piped up, I would pay out some nylon.  The added scope would be welcome.

Steve

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1 hour ago, Panope said:

For the record, I normally anchor with all chain and almost never set up a snubber because a somewhat oversized, modern anchor has much reserve holding power.

Plus you have a metal boat with heavy duty hardware and you are not concerned about ripping the chain stopper or the windlass out of the deck during gusts and shock loads...

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1 hour ago, Jim in Halifax said:

Plus you have a metal boat with heavy duty hardware and you are not concerned about ripping the chain stopper or the windlass out of the deck during gusts and shock loads...

True.

Plus, I sleep like death and am not bothered by chain noises that transmit into the hull like a megaphone.  In fact, I kinda like listening to the groans and grumbling of the chain as it works its way around the bottom.

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11 hours ago, Panope said:

The above does not consider surge.  I assume that a mostly nylon rode will have better surge energy absorbing capability than the all chain rode.

Steve

 

The energy absorbed by a spring is 0.5 * k * d^2. Note the d^2 term in particular. A rode that stretches 2 ft rather than 1 ft absorbs 4 times the energy. Chain has a very high k. If you integrate the energy absorbed by straightening the catenary, k is a function of load and goes very high as the catenary approaches straight. The problem is the distance moved to remove the last bit of sag is very, very small, so that the energy absorbed is low. In addition, this is a dynamic event: the chain is being pulled up rapidly and inertia may supply the last few feet of travel. I've no idea how the drag of the chain through the water contributes, and it would be a pretty complicated calculation I think, but it must contribute something. 

The d^2 term is why you want to use a relatively small and long nylon snubber. If I go from 1/2 to 3/8", the k is down 44%, at the same load it will stretch 77% more and absorb 77% more energy. If you double the length, the k is 50% less, distance is double and energy absorbed is 2x. 

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I should do a bunch of my 3.5 knot reversal tests with a mostly rope rode (and an anchor with bullet proof resetting capabilities).

I've done this so many times with all chain, the difference in deceleration should be readily apparent.

The fact that some of these (45lb.) anchors can flip over backward, reset, and stop (from 3.5 kts.) a 15k lb. boat in ONE ANCHOR LENGTH (with a nonelastic rode), is quite remarkable.

Steve

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I think Steve should re-test every anchor he's ever done, on each kind of bottom type with mixed rode, and he has to swap out nylon 3-strand and then 8-plait, then 12-plait rode.

Then test each configuration at 3.5:1,  then 5:1 then 7:1 scope.  Detailed video and commentary, please. ;)

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7 hours ago, Ajax said:

I think Steve should re-test every anchor he's ever done, on each kind of bottom type with mixed rode, and he has to swap out nylon 3-strand and then 8-plait, then 12-plait rode.

Then test each configuration at 3.5:1,  then 5:1 then 7:1 scope.  Detailed video and commentary, please. ;)

To be completed no later than yesterday  ;) 

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29 minutes ago, Autonomous said:

And dancing girls.

Now you're talking. Enough of this tethered camera stuff, it frequently gets covered in mud or weed.

Mermaids. Girls wearing 6mm neoprene bikinis handling the cameras.

Of course, they would have to dodge the anchor coming down, but think of the ratings!

Patreon's going to love this.

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  • 2 weeks later...
  • 2 weeks later...

Well that's certainly dedication to the craft, Steve.

I used my Rocna Vulcan 15 for the first time this weekend. A minor plot twist is that the bottom is sort of a hard clay once you get through a shallow layer of fine silt.

I used 3:1 scope. The anchor did seem to drag a bit, maybe 3-4 anchor lengths. Around midnight, the wind briefly piped up to 20 knots before settling down to 10 knots. The anchor held. When I raised anchor the next morning, the chain and anchor came up mostly clean except for a few chunks of clay which tells me that the bottom is pretty hard and challenging for any anchor. You could sculpt with this stuff or fire it into bricks.

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Steve, a couple of comments on catenaries. It is true that the chain will have an angle down from the bow (or tree), and the tension in the chain will be higher than that seen by your load cell at the anchor end. However, the tension can be resolved into a horizontal and a vertical component vector, where the horizontal one is the only thing keeping your boat in place and the vertical one merely increases the boat's displacement. The horizontal component at the bow, and the horizontal component at the anchor will always be equal. 

You touched of surge, and the catenary's ability to absorb surge. From an energy standpoint, the chain can only absorb the energy required to raise it from its static catenary to a straight line. This isn't very much. A simulation of that would be to drive away from the tree with your truck at 2 or 3 knots simulating the boat backing down with a surge. The chain will whip up to straight (and beyond), lifting say 100 lbs of chain an average of 15', or 1500 ft-lbs. A 30,000 lb boat backing down at 3 knots is about 9000 ft-lbs if I've done the math right.  A secondary (or perhaps it is primary) dampening force is that in water, on a sudden surge, the chain will resist this whip due to its drag in through the water. That effect is hard to calculate or measure, but must have some value. But as you stated, a stretchy snubber is more effective even if the tension it can provide is low. A 30', 1/2" 8 plait snubber that stretches 20% (about what nylon will do) absorbs about 9,000 ft lbs. A 50' snubber will absorb about 15,000 ft-lbs  - so a few extra feet on the snubber makes a substantial difference due to the x^2 term in the energy of a spring. In absorbing the 9000 ft-lbs surge, the 50' will see a max tension of about 2/3 what the 30' snubber would see, easier on the anchor as well. 

Keep up the good work!

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6 hours ago, DDW said:

Steve, a couple of comments on catenaries. It is true that the chain will have an angle down from the bow (or tree), and the tension in the chain will be higher than that seen by your load cell at the anchor end. However, the tension can be resolved into a horizontal and a vertical component vector, where the horizontal one is the only thing keeping your boat in place and the vertical one merely increases the boat's displacement. The horizontal component at the bow, and the horizontal component at the anchor will always be equal. 

You touched of surge, and the catenary's ability to absorb surge. From an energy standpoint, the chain can only absorb the energy required to raise it from its static catenary to a straight line. This isn't very much. A simulation of that would be to drive away from the tree with your truck at 2 or 3 knots simulating the boat backing down with a surge. The chain will whip up to straight (and beyond), lifting say 100 lbs of chain an average of 15', or 1500 ft-lbs. A 30,000 lb boat backing down at 3 knots is about 9000 ft-lbs if I've done the math right.  A secondary (or perhaps it is primary) dampening force is that in water, on a sudden surge, the chain will resist this whip due to its drag in through the water. That effect is hard to calculate or measure, but must have some value. But as you stated, a stretchy snubber is more effective even if the tension it can provide is low. A 30', 1/2" 8 plait snubber that stretches 20% (about what nylon will do) absorbs about 9,000 ft lbs. A 50' snubber will absorb about 15,000 ft-lbs  - so a few extra feet on the snubber makes a substantial difference due to the x^2 term in the energy of a spring. In absorbing the 9000 ft-lbs surge, the 50' will see a max tension of about 2/3 what the 30' snubber would see, easier on the anchor as well. 

Keep up the good work!

Thanks DDW,

Regarding the "angle down from bow", I agree - horizontal vector will be identical at both ends.  I mentioned the "down angle" because during both occasions that I measured Panope's "pull", the chain (and therefore the pull) was angled downward.  These instances were the "anchored in 20 knots" data and the "Max engine reverse thrust".  Both these cases were used heavily in the video to relate the "tree catenary" to the real world.

I tried and failed to produce a coherent presentation that delved into the surge absorption thing.  I blathered on about (chain) inertia and my "drag through the water" findings (see pic).  In the end, I deleted it all because I did not want to "lose" the audience.  I was reminded of what Stephen Hawking wrote in the Acknowledgments of "A Brief History of Time".  He said that he received the warning that for every equation he presented, book sales would be cut in half (he did include one - E=mc2). 

In the end, I figured my "energy absorbing distance" presentation would suffice to indicate just how poor chain catenary is at absorbing surge.  I'll admit that I was quite surprised at how small the horizontal movement was with respect to removing catenary.   I did not load the rig past 1000 lbs., but given the trend, further doublings of load would result in only an inch or fractions of inches of horizontal distance.

This 1 foot chain segment weighs 1.4 lbs. (in water) and free falls at 3.7 feet per second.  The wooden "feathers" (near my head) keep chain oriented horizontally).  Using the gravitational force (1.4lbs.) we can calculate the drag at the measured speed.  The trick is trying to figure out just how fast the chain rises in a real world surge.   Maybe I will make a dedicated video on the subject.

RbwTobs.png

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I think devising an experiment to measure the effect of chain hydrodynamic drag while straightening a catenary would be difficult without a military budget. At best though, it will increase the chain tension seen by the boat for the first bit of travel. As your demonstration proves, the boat only moves 26" from static 20 knots to essentially chain straight, an extra 1000 lbs even over the whole two feet is only 2000 ft-lbs of energy (and probably a lot less). Not nothing, but no where near what a stretchy snubber will do. 

That experiment to measure the drag of a foot of chain was actually brilliant. 

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To measure the "speed" of the straightening of catenary, I was thinking to attach a 20 foot stick of wood at the mid point of the anchor chain such that the stick will "float" into the vertical position.  With the upper end visible above the water (like a dead head), the stick will travel exactly as the chain does.  Add some brightly colored marks to the stick and a person in a nearby dinghy with a stop watch, and I could get some descent data.

 

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That would give you the speed of the middle of the chain, but is only a small part of the equation. As you travel towards the ends it moves less (and slower). Each foot contributes a different amount of drag, and the shape is not a simple catenary anymore (could be modeled with catenary equations for a non-uniformly loaded cable). And then the tension would have to be calculated or measured. From the energy argument I think we (I, at least) already know the broad answer: the catenary does not contribute much to energy absorption unless there is a BIG droop. It could be a lot of work to prove. 

Maybe a kellet combined with a drag device. I had an experience with a "reverse kellet" in the BVI on a charter once. Tied to a mooring buoy at the Bitter End, huge gusts of wind rolling around that hill and through the anchorage all night. We used a fairly long pennant, maybe 20' to the 3' diameter buoy. At each gust, the boat would surge backward, pulling the buoy underwater as the rode and pennant came straight. The floatation of the buoy softened the jerk at the end a bit. The the gust would quit, the buoy would shoot to the surface, accelerating the boat ahead to several knots, which would then ram the buoy with a loud clunk. All night long, probably 100 times. Not a restful night. A kellet of the right weight would sink the chain to a larger catenary, when the boat surged back the drogue attached to it would resist the lift in a soft way. Still, a lot of gear on the bottom compared to how simple and effective a nylon snubber is. 

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44 minutes ago, DDW said:

 ...........From the energy argument I think we (I, at least) already know the broad answer: the catenary does not contribute much to energy absorption unless there is a BIG droop. It could be a lot of work to prove.  .........

Include me in that sentiment, for sure.

Further testing on this subject would be driven by the 'geekdom' factor (youtube hits would would also be welcome).

 

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  • 2 weeks later...

I found our Spade liked ~4:1. It was not great at short scope. It was the Aluminum A120 (33 lbs and seems to be out of production).

 Really liked it but we did bend the shank sideways a bit in Bora Bora.

I'm sure the thinner shank is a cost saving measure too.

It held in > 80 knots sustained on about 4:1.  Wasn't expecting that much wind...

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We bent a Spade aluminum shank in Carriacou. I was demoing an Atlantic 42, pulled the anchor up to short scope and then gently drove it out. It was not very abrupt or anything - far less than your reset tests, buried in sand bottom. Anchor came up with the shank bent about 30 degrees (twisted sideways). I believe Spade replaced it for the owner. The steel ones (got two now) have worked well and without any issues. 

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23 hours ago, DDW said:

We bent a Spade aluminum shank in Carriacou. I was demoing an Atlantic 42,

We, too, bent an Al Spade shank on and Atlantic 42. Also, IIRC, 30-40 degree bend. We were on two anchors to limit our swing in the tight harbor at Rarotonga and I think that contributed to the shank loading. The second anchor was also Al (Fortress) and it did fine.

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We cruised with a Spade A80 on our 31 foot boat, 7 years 34000 miles.  Never bent the shank but we did wear through the forward edge weld of the shank exposing the interior.  Spade sent a new anchor to us in Fiji and we proceeded to wear out the second anchor the same way.  Too much coral I guess. Having said that we loved the anchor.  It dragged only once, thin sand over rock bottom, and held in everything. 

Just get the steel version as Spade, now, recommends.

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2 hours ago, gwilcox said:

Spade sent a new anchor to us

They got us a new anchor in the Cooks. First rate service. We went up one size in Al and got 15 years of excellent service from the replacement before it stated to show serious wear while full time cruising in the Pacific. Yes, I agree, steel is probably the way to go.

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On 11/2/2015 at 6:08 PM, Panope said:

Thanks everyone,

Alex W, was kind enough to lend me the Fortress but after the test I ended up buying it from him (Alex, did you get my check in the mail?).

Today I bought 12 feet of 5/16" chain and some 9/16" nylon and I am splicing it up right now. Tomorrow I will try and re-test the Fortress with this mixed (mostly rope) rode and see if the anchor behaves differently. This smaller sized, mixed rode will likely represent what most people are using with this Fortress anchor.

Another test I want to do with the fortress is to set it up on the stern rail and deploy it (throw it overboard) while under-way and see if it will hook up and crash-stop the boat. That test might be very difficult to video as the motion may have the camera pointing every which way but at the anchor.

 

Steve

Hey Steve @Panope

By any chance, have you ever tested a folding stainless Northill?  I picked one up for fairly cheap years ago in a “sure, why not?” moment, after reading comments by a guy named Jon Eisberg, sadly now passed, an experienced multi-vessel delivery skipper and sailor who used to swear by these (perhaps not having actually used one yet, which might result in swearing at it) as a “Big Bertha” storm anchor for himself.  (He also sailed a Chance 30, so likely had limited extra storage space). As you know, regular Northills are common on west coast fishing boats.

He was a prolific forum poster with lots of experience and referred, in his posts (search SA) to the Pekny anchor - which it turns out (I didn’t know) is a take-part type of stainless Northill.  Mine is not a Pekny, but is instead a folding Northill (and partially take-apart, I think) so might react differently (fold up?!?) under big load, etc?!  Very fine construction.  Certainly only a backup emergency anchor...not sure how far I’d trust it, but fortunately it’s in excellent condition and all the stainless welds appear clean.

As you may know (you’re a pilot, I recall reading? and as an internet search reveals), these were apparently manufactured as seaplane anchors, as these planes might require an anchor with strong holding power relative to weight (and had limited storage space on board). 

Anyway, I just happened to come across this somewhat interesting but certainly inconclusive video (not in water, or seabed, and no upward pull) and was just curious about your experience with these.

Pic of Pekny anchor at bottom from an ad in the back of an old 1990s Cruising World mag, archived in Google Books.

 

DCD22B94-A6B4-41B1-A837-31EA62BC4C0D.jpeg

A34A8C45-0418-4C94-B7CF-969EDA003BEF.jpeg

3D48302D-FCCA-483A-A880-C78C505464E2.png

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Steve just bought one. I happen to know because he bought it from me and I hope he tests it. I carried it all over the Pacific but it stayed inside as a spare while I used a galvanized NorthHill as my main and a Danforth as the second.

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Jud,

I have done significant testing of Russell's 11lb. Stainless Steel Northill Anchor, but Nothing has been published yet.  Stay Tuned.

That said, I have posted numerous tests of 14 lb. Galvanized Steel Northill.  

In short, they: set very reliably, produce low to moderate holding power, and are susceptible to having the rode wrap around the lazy fluke. 

Cool anchors.

Steve

 

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On 10/23/2020 at 5:05 AM, MikeJohns said:

Looking at other mud anchor tests, the stronger High tensile steel Danforth of equivalent size weights 50% more and performed pretty much identically for 32 degrees.

The Fortress wins when the flukes are at 45 degrees rather than 32, then there is 80% more inline projected area and more mud engaged. Whether that's very beneficial is debatable, I think it might be possible to exceed the sensible material design stress in alloy anchors. 

https://www.boatingmag.com/top-anchors-tested/

 

In fact, it was a very good test data set, witnessed by good independent people, when the full report and data were on-line. But under new management, Fortress took down the report and all of the copies, which described the set-up and showed the trial-by-trial data.

The take aways?

1. All of the data was extremely variable, with best to worst result often varying by 5-10 times. Perhaps the best anchor is the one that is most consistent, not the one that held best? By that measure, Mantus and Manson Supreme won, since they always set.

2. All of the anchors took considerable distances to set in mud.

3. Fortress won, not because they cheated, but because they sponsored a test on a bottom type (soft mud) where they have the best anchor.

I have tested many of the same anchors at the same location, and the results are valid. My data looked a lot like theirs.

 

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On 12/14/2020 at 12:05 PM, Panope said:

(Video)

Just to share, I did similar torture tests (including anchoring a similar sized boat!) and got very similar holding capacity.

Just so people know, the holding capacity you get with the anchor is moving and the holding capacity it will hold static are a bit different and depend on the bottom type and fluke type. Typically, any anchor will hold about 2/3 static what it will hold just creeping. I tested with winches and generally reported what the anchor would hold for a minute without moving. But this typically does not change the rank ordering and would be super difficult to do with Panope's set up. Which is fine. I love his set-up.

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On 12/16/2020 at 8:59 AM, thinwater said:

In fact, it was a very good test data set, witnessed by good independent people, when the full report and data were on-line. But under new management, Fortress took down the report and all of the copies, which described the set-up and showed the trial-by-trial data.

The take aways?

1. All of the data was extremely variable, with best to worst result often varying by 5-10 times. Perhaps the best anchor is the one that is most consistent, not the one that held best? By that measure, Mantus and Manson Supreme won, since they always set.

2. All of the anchors took considerable distances to set in mud.

3. Fortress won, not because they cheated, but because they sponsored a test on a bottom type (soft mud) where they have the best anchor.

I have tested many of the same anchors at the same location, and the results are valid. My data looked a lot like theirs.

 

Definately, all anchors have the conditions they suit. There's going to be no single best anchor, just the best overall with a bit of a  compromise in some bottoms.

It's a pity the manufacturers don't come clean and say what bottom types their anchors don't suit. 

The Fortress is just a Danforth pattern anchor, but worth noting the difference in the 45 degree fluke angle, that's very significant. Theory always said that 45 was best for soft bottoms but given the result it's worth modifying any Danforth pattern for 45 to use as a dedicated mud anchor. It'll dive deeper into the mud and consequently provide greater holding.

Results were taken down by Fortress but are in the pdf I attached before. To download click here http://forums.sailinganarchy.com/applications/core/interface/file/attachment.php?id=400578

 

 

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On 12/20/2020 at 10:30 AM, gwilcox said:

Yes indeed! Nobody knows the original name. You knew the builder in the south pacific? that's so kool. He built quite a boat.

Yes, sorry for the thread drift. We met Mike and Patty in the Marquesas and cruised the Tuamotus, with them.

Really liked the boat, design and build. The interior wood was simply stunning. 

We were on an English built Carter 30 for 5 years.

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  • 2 weeks later...
Just picked up a good condition 70 lb. Luke (three-part, disassembles) for really cheap. As in cheap!  Way, way cheaper than they sell for new: http://www.peluke.com/marine-hardware/boat-anchors/  It was too cheap to pass up. And I didn’t have a proper “storm anchor” for any possible future serious high latitude cruising.  Inspired by those who’ve cruised southern Chile, where such monsters can save your life :-)  
 
Here’s an interesting record of anchor types used, with frequency, in a 70 day cruise in southern Chile. One particular hairy sounding situation anchoring almost literally to the side of a cliff, and even with four lines tied to shore, didn’t feel safe...from an Ocean Cruising Club write up (Flying Fish Magazine).  Interesting data:  https://liveicomgrshot.blob.core.windows.net/occfiles/ffarticles/Flying_Fish_2005-2_1241.pdf
 

 

 

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1 hour ago, Panope said:

 

Great stuff, Steve.  As I mentioned a bit up thread, I picked up one of these several years ago for cheap. (But it’s around 30 lbs - I think the theory with these is that they’re supposed to have good holding relative to their weight?)  I look forward to your test results.  Please, no spoilers here :-)

(Today would be a good testing day for it, like y’all down there right now, we’re getting SE 30-40 up here today.)

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22 hours ago, Jim in Halifax said:

A Fisherman will hold your boat in rocky or weedy bottoms better than anything (as long as its heavy enough). Good score. I keep waiting for such a deal...

A Northill is the more modern equivalent, with MUCH better holding in every other bottom type.

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1 hour ago, thinwater said:

A Northill is the more modern equivalent, with MUCH better holding in every other bottom type.

I guess the potential issue with a Northill is stowing it - unless you can find a take-apart stainless steel Pekny, the disassembling version of the Northill.  No longer made.

Which is why, I suppose, people still use take apart Fisherman/Luke anchors? (The one below is on deck, ready for use, but could easily be broken down and stored below. Not my boat.)

I’ve got a folding Northill (stainless steel), but it’s still a bit too bulky to carry easily.

14F96A5D-DD14-4D38-8011-F7E1AF0043CE.jpeg

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On 12/19/2020 at 12:31 AM, Panope said:

Thinwater, thanks for chiming in.  Always good to hear of your results.

Steve

 

This one was great Steve.  It's something that is not as intuitive as one would think.  The idea of inline pull makes it seem simple but it certainly doesn't work that way.

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Very nice. Really.

Interestingly, you got much better results than I generally did. First, you used perhaps the best pairs to start. The bottom is also one of the best types for tandems (sandy mud).  I had many results were the veer test (the only test that matters IMHO) was  much worse, and certainly less consistent. The primary just rolls out. The reduction can be more or less, depending on the bottom and sequence.

Some primaries, because of differences in balance, will never reset if the tension is maintained. The roll bar will keep them inverted, like a kellet.

Obviously, it is tricky to get the spacing between the two anchor just right. If you don't it will probably fail. There are also some recovery complications. For example, you really need to get the primary on the roller before the secondary comes tight. Otherwise, there is side force and you can't board the primary through the roller. I generally used a recover line between the anchors (disconnected and them used to board the secondary).

I didn't test much at short scope. As you say, it is a storm method.

The only conditions were in-line tandems were better were hooking rocks and friction (hard pan or thin sand layer), and scope needed to be very long.

---

Steve did not show just HOW important it is to attach the secondary rode at the lowest point. If you use one of the higher holes the primary will roll out at half the force or less and will never reset.

The designer of the Spade specifically did not recommend in-line tandems. This is in his book on anchoring.  I researched this a few years ago, and I believe that ONLY Rocna ever recommended in-line tandems, and I do not believe the new owners do. The common wisdom is to use a primary of the correct size.

---

What would make some interesting testing (I've done a good bit on this) is testing an asymmetric V,  where a good veering anchor is primary, the secondary can be either Fortress or a good veering anchor, and they are set in a 90 degree or so V.  They are on one rode where it meets the boat, with a link underwater. The legs are perhaps 20 (primary) and 40 (secondary) feet respectively.  Depending on the bottom, they can work together, reducing the impact of veering and not fouling. I look at this as a soft mud method, where some dragging is nearly inevitable and it is hard to get enough holding. For example, the secondary may have to be a Fortress to get the hold when anchoring in soup, and the primary serves to reduce the veer. Not only can two anchors hold more in this configuration, they can do what perhaps no single anchor can: hold in very soft mud and withstand veering. I have probably not explained this clearly, but this is not a Bahamian moor.

V-tandem

Yes, there are some tricks to setting it. Not difficult, but only for special circumstances. My most common use was to fix the boat while I winched other anchors towards me under great force, not overnight anchoring.

  • Two rodes do not come aboard. That will tangle if the boat spins in the night.
  • An extension is often clipped to the secondary rode to facilitate recovery.

 

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I should add that the leg length I suggested for a V-tandem are for very, very soft mud, where an anchor takes 10 feet of more to set and sets at least several feet deep. In firmer bottoms, the lengths would be much less. On the other hand, it is impractical for the spacing to be less than the water depth. Really, it is a super-soft mud technique, and probably few people would try it. That said, I have found it very reliable at very high test loads, and it never tangles or fouls.

 

One anchor is best.

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I was lucky enough to be rafted up beside Peter Smith a few years ago (inventor of Rocna) and once he found out I was interested in all things anchor related we spoke about the different anchors and different practices.  I queried him about the tandem anchor recommendation with the Rocna and I didn't get the impression he was happy about the question.  His only response was that it was only ever to be used in extreme circumstances when the wind direction was known and wouldn't compensate for an undersized anchor.... I never understood the idea and really didn't see the point of it after that comment, but chose not to question him further.

Smart man though, interesting to talk to, when he was in a talkative mood.

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16 hours ago, tDot said:

I was lucky enough to be rafted up beside Peter Smith a few years ago (inventor of Rocna) and once he found out I was interested in all things anchor related we spoke about the different anchors and different practices.  I queried him about the tandem anchor recommendation with the Rocna and I didn't get the impression he was happy about the question.  His only response was that it was only ever to be used in extreme circumstances when the wind direction was known and wouldn't compensate for an undersized anchor.... I never understood the idea and really didn't see the point of it after that comment, but chose not to question him further.

Smart man though, interesting to talk to, when he was in a talkative mood.

I probably should have amplified, and Steve may test this, that there are several conditions where in-line tandems work, though moving somewhere better is smarter. All of them involve bottoms where the anchors cannot penetrate:

  • Hardpan. All you get is friction, and maybe a very thin sand covering. There are a few areas like this near my home.
  • Scattered rocks where marginal hooking is the game. With two anchors, if the one that is hooked gets loose, there is a much better chance of rehooking before the boat gains speed. Think about barbed wire; you get recaught before you get loose.
  • Cobbles. A combination of the above. Unless a single anchor can penetrate. Depends.

Yes, the anchors are going to roll, but they were never set anyway.

The other key is that you need MAJOR scope, because you do not want the rode lifting at all. Any lift unweights the anchors, and they are only resisting uplift with gravity, not digging. As much as 20:1 may be required (the second anchor doubles the pull, so double the scope to avoid uplift).

Basically, you need to be in a place with no other options, and hopefully, settled weather. But a monster single anchor is still much better, since it might penetrate.

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17 hours ago, tDot said:

I was lucky enough to be rafted up beside Peter Smith a few years ago (inventor of Rocna) and once he found out I was interested in all things anchor related we spoke about the different anchors and different practices.  I queried him about the tandem anchor recommendation with the Rocna and I didn't get the impression he was happy about the question.  His only response was that it was only ever to be used in extreme circumstances when the wind direction was known and wouldn't compensate for an undersized anchor.... I never understood the idea and really didn't see the point of it after that comment, but chose not to question him further.

Smart man though, interesting to talk to, when he was in a talkative mood.

I randomly came across this link below a few months ago, and it convinced me, and now in concert with Steve’s excellent tandem anchoring video data, that I don’t ever really want to tandem anchor - unless a serious situation.  

Peter Smith writes, “Tandem anchoring is for extreme situations, in which a single anchor large enough alone would not be practical for daily use.  Let’s pause to reiterate this. It is a mistake to think to tandem anchor regularly. You must have a primary anchor of a good size and type for your boat.  If not, get one.  [...]  

[from the conclusion] “Before attempting to use a tandem anchor rig, it is critical to understand the theory. The bar is raised very high, higher probably than most sailors have the experience for. By the time a mistake is realized, it is frequently too late, the conditions not permitting any correcting action. Examples of scenarios that can arise from misunderstandings are presented above in the case studies.  In addition to studying the theory and properly planning your rig, it is suggested that you practise deployment, setting, and retrieval in manageable conditions before having to depend upon it for real.”

So - I recently acquired one of these (luckily for quite cheap):

FE360F27-A8B4-400F-8E41-D3A543E855DB.png

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1 hour ago, Jud - s/v Sputnik said:

... I don’t ever really want to tandem anchor - unless a serious situation.  

Peter Smith writes, “Tandem anchoring is for extreme situations, in which a single anchor large enough alone would not be practical for daily use.  Let’s pause to reiterate this. It is a mistake to think to tandem anchor regularly. You must have a primary anchor of a good size and type for your boat.  If not, get one.  [...]  

[from the conclusion] “Before attempting to use a tandem anchor rig, it is critical to understand the theory. The bar is raised very high, higher probably than most sailors have the experience for. By the time a mistake is realized, it is frequently too late, the conditions not permitting any correcting action. Examples of scenarios that can arise from misunderstandings are presented above in the case studies.  In addition to studying the theory and properly planning your rig, it is suggested that you practise deployment, setting, and retrieval in manageable conditions before having to depend upon it for real.”...

 

In fact, this is NOT a correct interpretation of what Panope or I have said. Tandem anchoring is WORSE than a single anchor in nearly all situations, including storms. The ONLY times it is better is in a very few, very specific bad bottom types, not "serious" situations. There is no consistent evidence that suggests that in the real world an in-line tandem will hold more  than a single anchor. In fact, in the real world (waves) there are more ways to lay a tandem wrong. All of Rocna's info was zero-veer, and in my experience, that just does not happen.

I wanted the method to work. I tried many variations. I read what Peter said forwards and backwards. I tested on many bottoms and with many anchor combinations. It would be so handy in my native poor holding mud. Panope tested some of the best ones, in the best bottom for this method... and it failed. It is even worse in less cohesive bottoms, like sand, or in firmer bottoms. It just does not work in bottoms where anchors can bury.

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8 minutes ago, thinwater said:

In fact, this is NOT a correct interpretation of what Panope or I have said. Tandem anchoring is WORSE than a single anchor in nearly all situations, including storms. The ONLY times it is better is in a very few, very specific bad bottom types, not "serious" situations. There is no consistent evidence that suggests that in the real world an in-line tandem will hold more  than a single anchor. In fact, in the real world (waves) there are more ways to lay a tandem wrong. All of Rocna's info was zero-veer, and in my experience, that just does not happen.

I wanted the method to work. I tried many variations. I read what Peter said forwards and backwards. I tested on many bottoms and with many anchor combinations. Panope tested some of the best ones, in the best bottom for this method... and it failed. It is even worse in less cohesive bottoms, like sand, or in firmer bottoms.

Anyway, my simple point, poorly written, was that, based on reading that article and seeing Steve’s excellent vid, I doubt I’d ever resort to tandem anchoring.  (And it looks like too much fucking around to set up and retrieve.)

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