Anchor Depth/performance Reversals

[Nomad Willy]

FF wrote;
“In that era the Danforth had just been invented and folks used MUCH heavier anchors.”

I specified the 50’s and 60’s. That’s 22 years after the introduction of rhe Danforth by your own claim. I never looked it up I just assumed you were right.
And the Danforth was a very lightweight anchor in 1960. Most of the boats w the davit lift (that’s the word I needed Delfin, davit) were over 40’. And most were Danforths as they stowed so nicely on deck. Few others do.

 

[foggysail]

Delfin wrote;
“The bottom conditions would be an important factor, don't you think? In addition, and just as a matter of pure physics, a heavier anchor is far more likely to sink into the sea bed than a lighter one”

You mean being dragged into the seabed I suppose. Any anchor just laying on the seabed wouldn’t just “sink” into it I’m think’in. But being pulled w X amount of tension the big anchor wouldn’t penetrate much and a little guy could be completely buried. That could have something to do w my success w smaller anchors.

I’m currious what anchor Shrew had too.

Eric— a few years back over at Cruisers, there was much discussion on the advantages of a smaller anchor over that of one much larger. I don’t remember all the details of the discussion other than it went on for some time.

The one thing I do remember is while I was there, no actual testing was ever done. So one can rationalize a smaller anchor setting deeper......depending on bottom conditions of course... than a larger heavier one. Personally, my choice is with large heavy ones. Then along comes Fortress

 

[Nomad Willy]

Foggy,
Here's my lightweight.
Started as a "15"lb (advertised) but was 18lbs. It's now 12lbs w the holes drilled. The holes didn't reduce the weight much but removing much of the shank and all of the roll bar did.
Same size fluke but far less drag so this one should penetrate deep and make the most of it's small size.
Here's a pic that shows how much I removed from the LE of the shank to make it sharp.

 

[foggysail]

You certainly are adventurous Eric.

 

[Nomad Willy]

Once an anchor is set good most all hold.
A buried fluke is a buried fluke.
Getting them to set is the trick IMO or should I say "in my experience"?

 

[RickyD]

My boat came with a 35 lb Fortress and a 55 lb Fortress. When I was researching anchors I found reports that the Fortress needed a 5:1 scope or more, probably because of the angle of the flukes to the shank. I frequently anchor in very tight quarters with many boats to contend with so I want to be effective with my all chain rode, anchor, and shorter scope. After much agony I just minutes ago received my Mantus 85 lb. The selling feature for me was the holding power with short scope, and that when on its side, 55% of the weight rests on the fluke point. Resetting looks to be very effective. Now, I have found that frequently where I anchor most I end up circling the chain. I do plan some extensive cruising in rougher conditions and I can always drop the Fortress 55 with 7:1 in a blow.

Also, with my 55 footer, I will need to anchor deeper. 100' on occasion. I only have 350 ft of chain, no nylon.

Once I anchored in 120' off the Casino at Catalina Island in my 32' sailboat. OMG. Took me four tries to finally figure out where I would end up. I had 60' of chain and 450' of nylon. Plus my hand crank windlass would only accept chain so I had to pull in the line by hand till I could hook the chain into the gypsy. Ahh but I was so much younger then, I'm older than that now. Hmmm sounds like a song.

 

[DDW]

Once an anchor is set good most all hold.
A buried fluke is a buried fluke.
Getting them to set is the trick IMO or should I say "in my experience"?

Many tests and much experience suggests that this is not true. More true in a nice firm mud or sand bottom. If we only could arrange to always anchor in firm mud or sand.

I've had a Bruce drag slowly but continuously for quite a distance. I've had a CQR come loose and drag at full speed across an anchorage, and that was after backing down on it, without any change in conditions.

On the sailboat we carry a 66# Spade bower and a 44# genuine Bruce on the bow, and a Fortress in the bilge. In 10 years the Bruce has never left the roller and the Fortress never been assembled, so I'd have to say I'm pretty happy with the new tech anchors like the Spade. I sold the 44# fake Bruce off the bow of the trawler the day I bought it, getting a Spade to replace it.

I also know from diving or looking at it, that in mild conditions the chain with no anchor at all would probably work.

 

[rgano]

Here is an anchor manufacturer who is not afraid to recommend scope.

The SuperMax anchor website suggests setting the anchor first at 3:1 scope and then again at 5:1 scope after which the following is provided.

Rigid Shank Super MAX Anchors,

Sand, hard mud, and coral use a 4:1 scope
Mud, increase the scope to at least 6:1.
Ooze or very soft mud, increase the scope to at least 8:1.
If all chain rodes are used, scopes may be reduced to 3:1, 5:1, and 7:1 respectively from the above settings.
Pivoting Shank Super MAX Anchors (the fluke to shank angle to the type of seabed)

Sand, hard mud, and coral use a 5:1 scope and the lowest hole adjustment (smallest fluke/shank angle)
Mud, use a 5:1 scope and the middle hole adjustment
Ooze or very soft mud use a 5:1 scope and the highest hole adjustment (largest fluke/shank angle)
In tight anchorages, using an all chain rode, you may move the setting to a more open position and reduce the scope to 4:1.

 

[DDW]

Here is a pretty good non-math explanation of why some chain is better than no chain, and all chain is better than some chain. About 8 times better.

I'm searching for, but cannot find, a British article in which the calculations were done at different depths to show that with chain, deeper anchoring requires significantly less scope than shallow anchoring.

 

[BruceK]

Yes indeed.....I posted my experience and there may be others who enjoyed the thrill of a Manson Supreme not resetting.

My old post explained here in the forums that we had a 180 wind shift while I was at the helm at mid-day enjoying the beautiful views at Lake Tashmo (Martha's Vineyard, MA) and noticed our 40' Silverton was rapidly drifting backwards in the anchorage.

The anchor was well set in 8-10' (shallow harbor) and we had been there for a couple of days or so. I had to start the engines or risk banging into others as we floated across the harbor. No way was that anchor ....80#s, all chain with scope of about 5..... going to reset!!!

I was forced to retrieve the anchor and clean the mud from it with a boat hook before resetting it. I do not personally care about so called pulling tests or resetting tests or claims "that anchor should not fail!" or "you must have done something wrong!" That sucker FAILED!

Foggysail, g`day,did you make a change of anchor choice, if so, what did you change to?

 

[Nomad Willy]

Foggy,
“That sucker failed”

You’ve been bit by the biggest variable in anchoring .. the bottom.
And of course the roll bar compacts the mud in the fluke to shank junction. Just drill holes in your Supreme like Steve G did in Anchor Setting Vids. He tried and tried to make it fail .. but couldn’t. No need for another anchor.

DDW,
Yes I’ve read that deeper \anchoring requires less scope.
Also if you use the same amount of chain in weight 1/2 chain is better than all chain .. the same weight. Chain is for catenary, coral or convenience. The latter is the reason most people use it or they like the sound “All Chain Rode”. Put the weight where it will do the most good ... somewhat near the anchor. Not near the boat.

BruceK wrote;
“did you make a change of anchor choice, if so, what did you change to?”
Would you recomend a Super Sarca? I would to anybody that has a setting problem.

 

[Nomad Willy]

rgano wrote;
“Here is an anchor manufacturer who is not afraid to recommend scope”

Anchor manufacturers are not afraid to recommend scope. It’s not recommending scope that they are afraid of. That sets the stage for their product to fail. Of that they are genuinely afraid. Recommend short scope and at some point it will fail. They will blame the anchor manufacturer and say “but you recommended it”. Whereas the bottom was probably the culprit. Or the user technique. Only you will know if short scope is OK if you use it for a considerable time .. successfully. But Steve G’s videos are hard to discredit. And I saw a lot of successful short scoping.
But there’s a lot of other stuff that enters into it. A big anchor at short scope burried only slightly may not hold half as well as one half the size burried deeply. Lots of variables.

 

[Peter B]

There was a thread whereas a member had a rode reversal experience w a Manson Supreme and after the reversal the Supreme didn’t re-set.
Also remember that when Steve drilled the holes in the Supreme’s fluke the problem evaporated. He said he just couldn’t make the holed Supreme fail. Back and forth many times he went. Well other manufactures can’t drill the holes we but we boat owners can.

No surprise there for me Eric. What he was doing there, was merely emulating the mud suction release function of the slots in the Sarca anchor range. Both Excel and Super have slots in some form or other. In the case of the Excel, he (Rex Francis) uses the outline of the Excel name itself as the slots. it works.

 

[BruceK]

No surprise there for me Eric. What he was doing there, was merely emulating the mud suction release function of the slots in the Sarca anchor range. Both Excel and Super have slots in some form or other. In the case of the Excel, he (Rex Francis) uses the outline of the Excel name itself as the slots. it works.

Indeed! And I`m interested in what foggysail,an experienced boat owner, would choose in place of the Supreme.
I hope Rex Francis/SARCA is well, he was a TF member, his anchor products continue to get good press here. I usually get to say "G`Day" to him at the Sydney Boat Show.

 

[FF]

"Here is a pretty good non-math explanation of why some chain is better than no chain, and all chain is better than some chain. About 8 times better. "

Great story , but the graph is bunk.

The scale of depth to scope would make one think the anchor would be yanked out of the bottom.

While there might be some up pull from a anchor at 7-1 or 8-1 its minor. Math major response?

I think anchors fail due to shock loads that drag them till they get to a crappy location .

Nylon gives the lowest shock loads in a blow , if not too heavy.

 

[DDW]

Great story , but the graph is bunk.

The scale of depth to scope would make one think the anchor would be yanked out of the bottom.

While there might be some up pull from a anchor at 7-1 or 8-1 its minor. Math major response?

The scale is the scale, it doesn't lie, but you can misinterpret it. The upward pull of a straight rode at 7:1 is 8 degrees. That is not minor. The point is you can do no better than pulling straight along the sea bottom, and chain does that to a much higher pull. And in deeper depths, does it with less scope.

Yes, using heavier chain near the anchor is better. For convenience, one size chain and no chain-rope splice is the best. Everything on a boat is a compromise.

 

[Nomad Willy]

DDW wrote;
“The point is you can do no better than pulling straight along the sea bottom”

DD there are some anchors that actually don’t performas well in high scope. I don’t know enough to explain but it seems to be true.
How an anchor breaks out probably has something to do w it. One would think anchors would come out of the seafloor in line w the rode. But some anchors come out butt first. Saw a Claw do that in Steve G’s vids. And probably related to the most amazing thing I know about anchoring is how the pull of the rode pitches the anchor’s shank (end closser to the boat) down hard on the seafloor. Never woulda thunk.

 

[foggysail]

Foggysail, g`day,did you make a change of anchor choice, if so, what did you change to?

Hi Bruce-

No, I still have the Manson on the bow pulpit. My poor experience with it was I believe entirely due to the muck that clung to it. But that does not mean I love the anchor its just that I have cycled a 44 Bruce, a 55 Delta, 88 Delta and as of now the 80 Manson Supreme. And yes the Fortress FX55 remains in the bilge.

I had high hopes for the Delta but both plowed slowly across the ocean bottom. My boat has a great deal of wind loading with it being entirely enclosed with canvas which could aggravate anchoring. This I do know, after all my expensive attempts to reliably anchor as we did with our old sailboat, my Wife now almost demands that I get a mooring rather than anchor.

I mentioned in a different post how I would like to reconstruct my bow pulpit to accommodate two different styles of anchors. I will have to see how much time I have to do so next winter.

 

[FF]

"I mentioned in a different post how I would like to reconstruct my bow pulpit to accommodate two different styles of anchors. I will have to see how much time I have to do so next winter."


Set it up to hold a Danforth 90H , but use a trip line or you may have to fight too much to get it back up.

 

[ranger58sb]

Sure.... presently there is provision for only one anchor at the bow even though I have two, a Manson and the other a Fortress. The only way to accommodate two anchors at the ready is to replace my bow pulpit with one that has two bow rollers with enough space for two anchors.

There's a mount system for Danforth-style anchors that uses a bow rail; the pre-assembled (in the case of a Fortress) would hand vertically, flukes up, shank pointing downward. Haven't tried it myself, and the length of the shank would likely be germane... but it's out there.

Should be easy enough to attach some a chain/rope rode and fling the sucker over the bow, use a snubber if necessary, etc.

My boat came with a 35 lb Fortress and a 55 lb Fortress. When I was researching anchors I found reports that the Fortress needed a 5:1 scope or more, probably because of the angle of the flukes to the shank. I frequently anchor in very tight quarters with many boats to contend with so I want to be effective with my all chain rode, anchor, and shorter scope.

IIRC, Fortress suggests setting at one scope, but then also says you can shorten scope afterwards, if necessary. Something like that...

-Chris

 

[Nomad Willy]

ranger wrote;
“IIRC, Fortress suggests setting at one scope, but then also says you can shorten scope afterwards, if necessary. Something like that... “

So did the Rocna rep when their Rocna’s performance was less than stellar at 3-1 scope in a big anchor test. Many of the anchors in this test held in the vicinity of 5000lbs rode tension. The best thing that Rocna guy ever said though. Getting set deep at 5-1 usually means you’ll hold quite wellat 3-1. But that wasn’t the test protocol.

 

[DDW]

DDW wrote;
“The point is you can do no better than pulling straight along the sea bottom”

DD there are some anchors that actually don’t performas well in high scope. I don’t know enough to explain but it seems to be true.

I would not own an anchor that requires a narrow range of scope to hold. How are you going to control that in 18' tides?

Any anchor might hit a rock and jump up I suppose. I discount tests of "claw" type anchors as the various copiers of the Bruce have such different geometries and constructions that they could be different anchors altogether. The original Bruce always tests well in setting, but less than stellar in holding ability. My new boat came with a 44# Lewmar "Claw" which was of spectacularly poor quality and markedly asymmetric geometry. Though never used, I sold it on the dock for $20 and felt guilty about taking the money. It really belonged in the bin. If you want a Bruce type, find a real Bruce on eBay or Craigslist, preferably one cast in Belgium and not Brazil.

Tests and experience have shown that there are anchors that set and reset reliably, and hold on scopes of between infinite and 3:1.

 

[FF]

"I frequently anchor in very tight quarters with many boats to contend with so I want to be effective with my all chain rode, anchor, and shorter scope."


Bahamian , style , 2 anchors and you can anchor in a really tight field.

 

[Peter B]

I would not own an anchor that requires a narrow range of scope to hold. How are you going to control that in 18' tides?
.....Tests and experience have shown that there are anchors that set and reset reliably, and hold on scopes of between infinite and 3:1.

Yep. Both Sarca models, the Super and the Excel do that.

 

[SailorGreg]

when to move on

In the past, when an anchoring boat "invaded my space" i used to get on deck and say something, but that wasnt good for my own peace of mind. Now I try and assess whether or not the new boat is close enough to keep me from sleeping. If he is, I leave if I can.
I find it hard to determine just how far away the other boat is so I have a hand held rang finder. Invariably the boat is farther away than I had guessed before I measured. Once I have an actual measurement I figure in scope and wind direction and determine if we have an issue or not.
I appreciate that what I think is "my space" may be larger than what others might think I deserve. I dont usually anchor in crowded anchorages, if I can help it I just dont go there. I passed on a trip to Block island for the Fourth, as an example. No way I could be comfortable.
The boat in the picture dropped her anchor about 20' off our beam then drifetd back on about 3:1 scope. St. Barts in the evening so no where else to go. No sleep. Sorry if the picture is up side down. Cant seem to fix it. Will right itself if you click on it.

 

[Nomad Willy]

DDW,
I didn’t say anything about Claw/Bruce anchors. Nor did I say anything about a narrow range. I’ll say now that short scope performance is as important as long scope. Too many crowded anchorages and too many small anchorages. Too many say they never anchor at less than 5-1. Hard to believe.

But you said;
“.....Tests and experience have shown that there are anchors that set and reset reliably, and hold on scopes of between infinite and 3:1.”

True but there are a few that are weak at 3-1, a very common scope to use. I think most or quite a few anchor manufacturers tune their designs for the upper end of the scope range so they look good on tests. Some (not that many(like the Supreme)) excell at short scope. When I’ve talked about weak short scope performance in the past some say “oh I use that anchor all the time frequently at 3-1 and I’ve never had a problem.” But they are anchoring in less or mostly far less than demanding conditions. The test that said the Rocna was weak (at 3-1 only) tested all the anchors to 5000lbs rode tension .. that were capable to that extent. The Supreme tested over 4500lbs at 3-1 in that test. That separates the “men from the boys” so to speak. But most all will not experience the short scope flaw. Also most won’t notice the lower performing anchors that tested at long scope with 40-50% less holding power than the top dogs. Some of them are the best anchors to have IMO. Very very few will put a 5000lb pull on a 40lb anchor in normal anchoring conditions. Selecting an anchor that is at the top of the heap for max holding power is often not as good as one that sets very well and has less than the top performing anchors for max holding .. always tested at longer scope.

Also too many of the best anchors are not represented in the major tests .. or any test. Some manufacturers know their anchors won’t max w the best and feel it’s not a good idea to get in the tests. Not cost effective so to speak. Steve’s Anchor Setting Videos didn’t say much about max holding power but more than you’ll otherwise know about setting performance. Like he said .. Setting Videos.

I’ve often said over the years here that setting performance is more important than holding power. But it’s easy and quite safe to bash the Claws as few will ever argue w you.

 

[MurrayM]

The boat in the picture dropped her anchor about 20' off our beam then drifetd back on about 3:1 scope. St. Barts in the evening so no where else to go. No sleep. Sorry if the picture is up side down. Cant seem to fix it. Will right itself if you click on it.

Yikes

For next time, perhaps you should have photocopies of the page in the Earl Hinz book about anchoring where he says "the last boat in is the first boat out" if any issues arise, and give it to the late comer

 

[psneeld]

Dropping anchor at your stern and drifting back is normal.

If its that tight in the anchorage, best ti know everyones scope on all sides of you before you settle in for the night.

3 to 1 is expected by many in fair weather overnight anchorages, 5 to 1 if windy but no storms and if you are intermixed with long term vessels....sure they might have 7 to 1 or 10 to 1 scope.

Like other dynamic things in boating, communications are the key.... as well as having a bailout/emergency plan...whether you were first or last in.

 

[DDW]

Saw a Claw do that in Steve G’s vids.

DDW,
I didn’t say anything about Claw/Bruce anchors. Nor did I say anything about a narrow range.

That's what I was responding to. If you eliminate long scope and we know short scope can be problem, now we have a narrow range.

I agree that ultimate holding power should not normally be the determining criteria. A Fortress or other large Danforth type usually wins in holding (at least in mud or sand). Yet I would not use this type as a bower, as it is less reliable setting and resetting. Setting ability it what made the Bruce popular. Bad copies have made it less popular again, but it does not hold as well as more modern designs. I note that after all his tests, Steve uses a Spade on his own boat. I've used a Spade for 11 years now all around the continent and it has been superb. It may have it's equals now, and certainly has it's imitators (the new Rocna Vulcan is a blatant copy, after bashing the Spade design for years).

In a crowded anchorage where short scope is required, a Bahamian moor isn't usually an option. You are going to stay put and the rest of the anchorage will swing into you with changing wind/tide. A range finder is a great idea because boats you think are close are often much further than you think.

 

[SailorGreg]

....he didnt drop off my stern, but my beam. After dropping back his bow sprit was no more than 40' behind me. And it wasnt that crowded. It was unnecessary, so he earns a jerk vote from me. He obviously didnt care about my vote, however.