Anchor Depth/performance Reversals

[O C Diver]

Tried to stay out of this, but just can’t resist. Let me start by saying this applies to the Bahamas, where we spend our winters. So, to all of those who think that letting the boat drift back to set the anchor will work in the Bahamas, please don’t anchor near me. As a gross generalization, the Bahamas has two types of bottoms, deep sand that will hold no matter how you anchor ( most of the Exumas) and thin sand over hard pack ( Black Point, most of Eleuthera, etc.)
We back down at 1000 rpm. What often happens in thin sand anchorages is the anchor will hold at 700 rpm, then pop out at 900 or so (55k Vulcan). I have gone in the water while my wife goes through the setting process. In thin sand the tip hooks on whatever, maybe 6” deep. Then when she backs down it pops out and drags. If we stick around and keep trying we sooner or later get a good set. Then we watch as the neighborhood goes to hell. Boats come in, use the “ let the wind set the anchor” routine, and start mixing their drinks. If they don’t threaten us, we pour a drink as well and get ready for the arrival of the squall that is sure to come.
When the wind picks up, equivalent pull to my 900 rpm backing down routine, the “ let the wind set my anchor” crowd wanders off towards the reefs. (If I may digress for a minute, this is classic Block Island entertainment as well)
So my comment to the “ let the wind set my anchor” skippers. If you have been getting away with this routine then you are lucky or anchor in an area where this works, maybe Chesapeake mud, but it is not a technique that will serve you well in the long run. You will never know if the anchor will hold in that next squall unless you try.
I have goon this far, so might as well comment on the scope issue. As to the Bahamas, once set I think 5:1 is plenty for anything less than a major front. I have dove on the anchor many times and at 7:1 and gusting 30 knots the chain never lifts off the sand for the last 20’ or so. Tells me I have more scope than I need. Same goes for Chesapeake mud. At 7:1, while retrieving the anchor after a wind reversal, it is apparent that the reversal never got to the anchor, in fact never got to the last 20’ of chain. So, for most conditions, 20 knots or less, my baseline is 5:1.
What our scope discussion is missing is wind and current conditions ( knowable facts) and the actual set conditions( often unknowable unless you can dive the anchor). So 3:1 may work well with 300’ of chain out in light winds and with the anchor embedded in the rocks, but will be totally ineffective in the Bahamas in 15’ of water and sand over hard pack. The challenge is knowing which is which. And if you can’t dive on the anchor, then plan for the worst.
If I get to an anchorage and 3:1 is all that will fit, I leave. If I get there first and have 5:1 because that’s what I feel I need to be able to sleep, I am not going to shorten scope to accommodate the next arrival.
And if the next arrival is a “drop the anchor and drift back” type, I leave. I probably shouldn’t hit send, but after a glass of wine, what the heck.

Two observations:
So I'm good everywhere on the East coast except part of the Bahamas and Block Island. I can live without that 1/1000 of 1% of East coast anchorages.

As mentioned previously, my boat sails at anchor. If I'm hooked on a ledge, it's likely going to come off fairly quickly.

On a more serious note, how do you know it won't find a ledge when it reverses? If the chain runs over the anchor on a reversal, they tend to come out as opposed to rotate in place.

Ted

 

[dhays]

What our scope discussion is missing is wind and current conditions ( knowable facts) and the actual set conditions( often unknowable unless you can dive the anchor). So 3:1 may work well with 300’ of chain out in light winds and with the anchor embedded in the rocks, but will be totally ineffective in the Bahamas in 15’ of water and sand over hard pack. The challenge is knowing which is which. And if you can’t dive on the anchor, then plan for the worst.
If I get to an anchorage and 3:1 is all that will fit, I leave. If I get there first and have 5:1 because that’s what I feel I need to be able to sleep, I am not going to shorten scope to accommodate the next arrival.
And if the next arrival is a “drop the anchor and drift back” type, I leave. I probably shouldn’t hit send, but after a glass of wine, what the heck.

Glad you sent. Big differences of course in different parts of the world. I’ve never anchored outside the Salish Sea for example.

I would argue with your contention that wind is a knowable fact. Up here, a random guess is sometimes the best we get as to wind. Current is predictable of course if I take advantage of the resources available.

The other difference is being able to see the anchor set. Other than Steve’s videos, how the anchor is set is really just a big mystery. We only know if the anchor drags or not and how firm the set “feels”.

 

[BruceK]

The other difference is being able to see the anchor set. Other than Steve’s videos, how the anchor is set is really just a big mystery. We only know if the anchor drags or not and how firm the set “feels”.

That`s so true. If we knew for sure what was going on and what the bottom was like where the pick landed,there`d be less speculation.Another of life`s little mysteries.

Steve`s SV Panope vids revealed which anchors reset well on a 180 boat shift, and there were not many. He also tested by shortening scope until breakout,and again got interesting results, some holding surprisingly well below 3:1.
Although Sarca figured well in both those tests,Sarca recommends 7:1, to my mind that`s a convenient "out" for a mfr knowing most boaters use less scope, if there is a breakout at lesser scope.
A number of bays we use are around 50ft deep, fairly small,and you expect company. Fortunately they are often sheltered. IMO selecting scope has to take a number of factors into account,7:1 might be the goal but in some circumstances could create more problems than it sets out to safeguard. And I`m not sure it takes into account significant anchor design improvements and the popularity of all chain rode.

 

[DDW]

In the Bahamas, or better still the Leewards, you can see the anchor set - even in 80' - from the surface. And in the Bahamas, there is rarely water that deep in any anchorage. There are places there where you can anchor in 15', well out of sight of any land.

In the PNW, the anchorages are usually quite sheltered and the wind normally light. But you are never going to see the anchor set without Steve's setup.

 

[markpierce]

Plenty of separation here, although the camera exaggerates the distance.

 

[BeeJay]

Nice photo, nice boat

 

[caltexflanc]

In a strange anchorage with dark water, you can check the chart and see if it has bottom information. You can look at reviews in various guides. You can drop a waxed lead line off the bow and see what it brings up. And with experience, you can get a pretty good sense by the way the anchor sets, including feeling the chain in front of the bow roller, which will as the boat drifts back, transmit if you are dragging along rocks or scraping.

In good bottoms of various compositions, the initial set is not the final set. That's where the "let out your rode, pour yourself a drink" approach works well. Mark your location. Let the boat and the weight and shape of the anchor do their thing for awhile, or "soak" as some put it. Have your drink, check the location, and power set if you like. The much maligned CQR has held thousands of boats in this manner, including a Grand Banks 49MY off Indian Key in the 10,000 Islands in a squall:

By the way, I attached a makeshift 3 strand "snubber" to the chain with a rolling hitch in this case, as it was a charter; worked great.

 

[caltexflanc]

I disagree strongly about there not being reversing currents on the east coast. There are very few places to anchor in the southeastern coastline in particular where there is not a reversing current.

 

[motion30]

The question is of course how close do you care to be to a bunch of boats that are anchored with 3to1 scope and you have no idea what kind of Ground tackle they have. I know sometimes there is no choice, but if there is.......

 

[O C Diver]

The question is of course how close do you care to be to a bunch of boats that are anchored with 3to1 scope and you have no idea what kind of Ground tackle they have. I know sometimes there is no choice, but if there is.......

+1

More than once I've asked people to anchor further away as their spot was to close for a forecasted change of wind direction.

I've also moved when another boat anchored within 40' of me and refused to move.

I used to trust that everyone in the anchorage knew what they were doing. I'm now focused on risk reduction.

Ted

 

[Nomad Willy]

Ted and motion,
This 3-1 scoper w a light anchor (likely even modified) has never dragged.
Astrologically I’m the luckiest of all signs though.
I’m more worried about my engine quitting than anchor failures. Even though anchor failures are much more likely.

 

[O C Diver]

Ted and motion,
This 3-1 scoper w a light anchor (likely even modified) has never dragged.
Astrologically I’m the luckiest of all signs though.
I’m more worried about my engine quitting than anchor failures. Even though anchor failures are much more likely.

Doubt you're anchoring in less than 10' of water.

Ted

 

[foggysail]

I disagree strongly about there not being reversing currents on the east coast. There are very few places to anchor in the southeastern coastline in particular where there is not a reversing current.

Right on!!! We once had fun anchoring in Nantucket at 3rd point in our sailboat. Woke up one night with a roaring noise that was caused by our anchor rode getting wrapped around the boat's keel forcing the boat to lay sideways in the current. Don't know if anchoring there is now allowed with the harbor almost/all completely filled with moorings. The owner of Nantucket Moorings must be a multimillionaire by now.

 

[foggysail]

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.

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!

 

[Nomad Willy]

Foggy,
All anchors can fail.
Could you have found a deeper spot perhaps w/o the bottom growth to fowl your anchor? But most roll bar anchors tend to be mud scoops. I’ll bet a Navy or Dreadnought anchor wouldn’t be terribly affected. A Kedge is about as weedproof as there is I suspect.

 

[psneeld]

I believe all anchoring situations can fail sooner or later.

It could be the anchor one time, technique another, a total anomaly others, etc.

Some have had 100% success with one type or technique, others have had a failure.

One recurring tid bit seems that the larget sizes of any design beem to fail less because of fouling. I can understand the theory behind why it might be true

 

[foggysail]

I believe all anchoring situations can fail sooner or later.

+1

 

[foggysail]

Foggy,
All anchors can fail.
Could you have found a deeper spot perhaps w/o the bottom growth to fowl your anchor? But most roll bar anchors tend to be mud scoops. I’ll bet a Navy or Dreadnought anchor wouldn’t be terribly affected. A Kedge is about as weedproof as there is I suspect.

Eric- the general area I wanted to anchor is shallow and muddy. There was no weed/grass on the anchor when I cleaned it, just black heavy mud. In fairness, if the bottom was anything other than sticky mud, the Manson most likely would have reset.

Next winter I hope to find time to remove the anchor's bulpit an make a replacement, one that can accommodate two anchors. Many places do well with Danforth styles and where I anchored is one. An ideal place to use my FX55 Fortress. Swapping anchors while out in the great beyond runs a high risk of dropping one into the swamp. And with the Manson weighing in at 80#s just changing it would be a pain.

 

[Nomad Willy]

psneeld wrote;
“One recurring tid bit seems that the larget sizes of any design beem to fail less because of fouling.”

That relates to the thread as another variable. However I may use the smallest anchors here and I rarely have even a slightly fowled anchor. The worst was in a shallow and large bay (Calder Bay) where there was a large comunity of SeaOtters. Black sticky and stinky mud that took at least 20 min to get off. But it fit my thread scenairo of shallow and fowl w (in this case mud) but the anchor held. A Danforth at 10-1 scope. Did that just because I could and felt I may never get the chance again.

But I think your big anchor theory is almost obvious. An oversized anchor would likely be mostly just sitting on the bottom w little penetration and thus less chance of picking up weed/salad. A light set not destined to fowl should hold a boat too, at least in mild conditions.

And Foggy one must consider mud to be the most often fowling to ruin an anchor’s holding power.

But overall ??? My anchors are small (even for my boat) and any fowling is rare. I’m assuming or guessing it’s mostly geography related. 0

 

[psneeld]

Just the opposite, as the boat starts pulling the BIG anchor the heavier weight overcomes any type of resistance that may foil a lighter anchor.

And of course......easy anchoring bottoms are not the problem.

 

[FF]

" Swapping anchors while out in the great beyond runs a high risk of dropping one into the swamp. And with the Manson weighing in at 80#s just changing it would be a pain."

Folks that understand the different nature of the sea bed will frequently carry at least 2 different Style anchors.

CQR and Danforth as examples of different styles. .

A bow roller built with at least space for 2 anchors allows the anchor line to be fastened to the chosen anchor with zero danger .
Smaller boats may simply mount a second bow roller .

 

[BrianSmith]

8 to 10:1 for me most of the time. All chain 35 Danforth in mud bottoms here in eastern LI Sound.
I let the drift initially set then I back down at 1000 rpm or so. I often have difficulty weighing anchor and a lot of mud to clean off the chain and I like it that way.

+1 (We're in the Bahamas, all over the place. Usually sand, or sand+mud. Depth is usually 8' to 20'.)

 

[foggysail]

" Swapping anchors while out in the great beyond runs a high risk of dropping one into the swamp. And with the Manson weighing in at 80#s just changing it would be a pain."

Folks that understand the different nature of the sea bed will frequently carry at least 2 different Style anchors.

CQR and Danforth as examples of different styles. .

A bow roller built with at least space for 2 anchors allows the anchor line to be fastened to the chosen anchor with zero danger .
Smaller boats may simply mount a second bow roller .

Next winter I hope to find time to remove the anchor's bulpit an make a replacement, one that can accommodate two anchors. Many places do well with Danforth styles and where I anchored is one. .

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.

 

[Nomad Willy]

No,
There are other ways.
In the 50’s and earlier larger boats had a curved mast small crane to lift anchors and the anchors were stowed on deck. The then popular Danforth and Yachtsman's anchors would conveniently lay flat on the deck.

Today one could have an everyday anchor on a bow roller and use the crane for the alternate anchor or anchors. The crane mast could also easily be folded and lie on deck. But the crane mast usually or always stood up in it’s working position judging from all the pics I’ve seen.

The mast dosn’t help the yachts lines but is far less unsightly than the typical bow pulpit we now see. But w a crane mast it could be painted black and thus visibly become almost invisable.

 

[foggysail]

No,
There are other ways.
In the 50’s and earlier larger boats had a curved mast small crane to lift anchors and the anchors were stowed on deck. The then popular Danforth and Yachtsman's anchors would conveniently lay flat on the deck.

Today one could have an everyday anchor on a bow roller and use the crane for the alternate anchor or anchors. The crane mast could also easily be folded and lie on deck. But the crane mast usually or always stood up in it’s working position judging from all the pics I’ve seen.

The mast dosn’t help the yachts lines but is far less unsightly than the typical bow pulpit we now see. But w a crane mast it could be painted black and thus visibly become almost invisable.

Come on Eric, are you suggesting adding a crane for anchor removal?

 

[Nomad Willy]

Foggy,
You’re thinking of a different crane.
But yes they were 3-4’ high made of steel tubing about 1 1/2” dia.

Here's one from a Chapman's book. 1994. A photo I just took from the book. This is a small one probably only 3'. Never used one before but the boom/mast probably rotates to lift the anchor 10-14" beyond the rail and then rotate to swing the anchor over the deck. On my own boat I lean a bit "over the side" to accomplish the same thing w my body.
Anyway in the photo you can see the mast/boom from pic ctr up and a little to the left is the white mast. Almost anyone could make one and the base. Could powder coat to whole thing in whatever color.
You can see that nothing protrudes beyond the bow of the boat. See the unfolded Herreshoff Yachtsman anchor on the deck lower right.

 

[FF]

In that era the Danforth had just been invented and folks used MUCH heavier anchors.

A 100 lb anchor on a 40 ft sail boat was not uncommon , although the better anchors would fold the crane made bringing it aboard to be lashed to the deck easier.

Today the watch fobs have done great advertising , so folks are happy with paying $20. a pound for cast iron or welded sheet steel.

 

[Mako]

You’re thinking of a different crane. But yes they were 3-4’ high made of steel tubing about 1 1/2” dia.

I had pretty much the exact same anchor davit on the bow of my 1956 Boat. There was no bow roller.

I anchored with a danforth but just lifted it over the rail. That davit was too much trouble and it was meant more for fishermen anchors.

 

[Delfin]

There are two camps I find in most posts. Those who actively set their anchor, and those that let momentum, wind and current set the anchor. Personally, I back down on the anchor until it's set, then rev up to 1,000 rpm to ensure it's buried.

I would be curious the method employed by the person who dragged after a reversal. I would venture a guess that those who use momentum might not actually be setting their anchor. When a reversal occurs, there is a higher chance of the anchor not properly setting.

I've reversed and sat in 35 kt winds 180 degress from the direction of set with no issues. When I dove on the anchor, it was so well buried, the anchor didn't even reverse direction. In other words, I was pulling backward on the anchor in 35 kt winds.

Sometimes I have a difficult time breaking the anchor free at 0 scope.

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, so those with 150#+ hooks may do just fine letting drift and current nudge the anchor into position. Seems to work for us. And, an anchor that has little resistance to burying itself will dig deeper than one with resistance. So many factors, it doesn't seem warranted to make general conclusions from specific cases.

Your observation of the anchor being so well buried it didn't change direction in 35 knots winds is telling. What it seems to say is that even in those conditions, the actual pull on an anchor is pretty minimal until you get into fairly extreme conditions. Just curious, but what anchor was this?

 

[Nomad Willy]

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.