Anchor Dragging Story (long)

[Montenido]

Hi folks,
I just returned from a lengthy stay in Mexico, some aboard my boat, and some aboard another boat. I had a very scary anchor dragging incident that I thought I would share. I was anchored with my wife in the south end of a place called "The Hook", on Isla San Francisco, in Baja. We anchored in calm conditions in about 12' on a sandy bottom. For tackle I had a new Manson Supreme 45# on 5/16 chain. I had about 100' of rode out, with 20' snubbers.

This particular spot normally has no waves due to being in the Sea of Cortez. No swell influence, although wind can change that. At this time of year northern winds are the norm, but we were experiencing a southern blow, so I was sheltered from that direction by the point. Anyway, the wind started to build around midnight, and was blowing a full gale within an hour or so. I got up to check on things at about 1:30am and all looked okay. About an hour later I was awakened by the sound of surf breaking on the beach. I looked out the rear port window and saw dry sand about 15' behind my transom! I yelled for my wife to wake up, started the engines, and turned on the windlass.

Fortunately, it was a full moon, so there was some night visibility. In the normally calm bay there were breaking waves across its whole width. Since I was worried that we might already be on the bottom, I used the windlass to pull us into deeper water. As soon as I felt that it was safe, I had my wife put both motors in forward and idle into the waves, while I retrieved our rode. Once we were clear, we motored to the mouth of the small bay and had a chat. It was too rough to head out, so we opted to drop the anchor in about 20' and let out 150" of chain. The anchor grabbed and dug in, but I stayed awake until the sun came up, and had the motors running for a while. Instruments told me that I was securely anchored, but I was not trusting them yet.

When daylight came, it was clear that we were anchored well, and I went to sleep. I was a nervous wreck after this whole ordeal. The wind stayed in the 20s from the south, so we spent another night in the bay. I have to admit that I replaced a 55# delta anchor that came with the boat with the 45# Manson. Why I got a smaller anchor I can not explain. Brain cramp or something. I re-installed the 55# delta for the coming evening, and it held just fine. We headed back to the marina the following day.

I don't know if I didn't set the anchor well enough to begin with, or what. I do think that the 45# was a bit small, and it certainly didn't hold in the initial wind and waves. On my last sailboat, I had an 80# Manson Supreme and loved it. I'm not blaming the anchor, it was just one of a few things that I probably did wrong. Although the incident left me a bit scarred, I do feel that we did everything right when the sh#t hit the fan. My wife was amazing, holding the boat steady in pounding waves and gale force winds, while I scurried about.

Back in the marina, I was able to swap my 45# Manson for a 55# Rocna, which was a great bit of luck. I haven't tried it yet, but it should be a bit better for my 32,000 lb boat. Thanks for reading. All comments and advice are welcomed, even negative stuff. I learned a lot that night that will help me be a better boater. And no, I did NOT use an anchor alarm, but I will from now on.

Cheers, Bill

 

[Mako]

Interesting story. Sounds like your anchor is sized about right per Mansons chart. Like you said perhaps it wasn't dug in enough initially and unfortunately it didn't dig itself in but just skidded along.

A shame you didn't keep that giant 80lb anchor from your other boat. In any case, the Manson will make a great kedge for you.

 

[sunchaser]

Shallow sand close to a beach can sometimes be a very poor bottom for holding. The reason for this is that all the fines have been washed away thus the coarse grains provide too little holding resistance. Couple that iffy notion with wave action and lots of vessel windage, the 45# anchor may have been just too small.

 

[North Baltic sea]

whether it would be possible for the anchor chain twisted stem. see the link page 42 rocna. the test took place in this way, and did not turn and dug (rocna) although it is a good anchor. possibly also from the beginning too short chain of outdoor risen relative to strong winds. fortunately have time to react to the last seconds before a big damage.


http://www.google.fi/url?sa=t&rct=j...HHfAxcnCEkjC7isNtODnyCpzLOGA&bvm=bv.146786187

 

[sdowney717]

Those two anchors look very much identical to me.

Could the long slot have been why it dragged, if the boat swung?
About the Manson Supreme Anchor

Design of the edge you think might aid in a Rocna setting well and keeping is set.

 

[Cliff Meima]

Sooner or later we all have that experience. I am glad you came out of it OK.

 

[Capt.Bill11]

F anchor manufacturers charts.

Personally I always recommend going at least one size larger than any chart suggests.

Put out the biggest anchor you can all the time. Just to avoid these kinds of situations. Especially if you have a powered windlass.

Plus use some kind of anchor drag alarm in a location where you can hear it clearly.

Glad you made it out OK of a scary situation.

 

[sunchaser]

F anchor manufacturers charts. Personally I always recommend going at least one size larger than any chart suggests.
.

+1

 

[Shrew]

It's interesting that the Manson sizing chart has a 40' -45' boat recommended to use a Manson Supreme 45Lb. However the Rocna sizing chart has you in a 33Kg (72LB). In your case, it's the weight of the vessel that is pushing you into the higher category. Manson is only using a length.

I would assume you would need to be in a 60lb Manson (I'd probably consider 80lb based on your story and the Rocna recommendations) or a 72lb Rocna.

I know Rocna indicates that they already oversize their anchor recommendations.

 

[Nomad Willy]

From all the tests we all know the Supreme holds extremly well if not choked w weed. Any sign of that? You were in an area w lots of sun and in shallow water and the water may be relatively clear (I do'nt know). A good recipie for lots of bottom growth.

I agree w Mako that the 45# anchor is'nt too small. With a lesser performing anchor, possibly so but not the Supreme.

The Manson should'nt have cared how you layed the anchor down. With one rather remote posibility. Your chain comming down on top of the anchor could wrap itself around the anchor such that it could have been pulled sideways or backward in a tangled up mass of chain and anchor. 100' of chain out on top of an anchor only 12' down meant you could have dropped about 75' of chain on the anchor.
I take care to avoid that scenario by dropping the anchor till it is on the bottom stopping and having Chris start backing and then paying out rode at a rate approximating the moving boat over the bottom. Paying out the rode in a quite straight line and don't start taking up slack until the planned length of rode is out. This way I ideally arrange the rode on the bottom as if there was no water and I was walking around on the bottom.

You made no mention of the bottom type and very likely did'nt know. Any anchor has a bottom or several bottoms that it will not perform well on. I know of no problematic bottom type for the Supreme except thick weed or salad (as Steve on the boat Panope) likes to describe the weed in his area. From the pics it looks a bit like tumbleweeds and kelp together so "salad" is the perfect word.
One more possible problematic bottom would be mud. Chesapeke Bay-like mud that is very uncommon. If you review the Chesapke Bay mud test by Fortress Anchors you will see the only anchor that could have held your boat in a gale in that rare slimy type of mud would be a Fortress anchor. The favorite anchor at that time was the Rocna. Amazingly the Rocna was about the worst performing anchor in the test. The Supreme did'nt do very well either I will add. And one should always keep in mind that the bottom is the most important and uncontrolable part of the anchoring bag of variables.

If you did'nt set hard the wind should have done that job .. possibly even better that a skipper as then the setting takes place slowly (the best way to set an anchor)

As you can see there are quite a few waterloos you could have fallen into. So if I were you I'd review your technique ... polish your skills if I may say so. Blaming the anchor or it's size is not the most probable route to this dragging to never happen again. The excellent holding capabilities of the Supreme is very well documented. It should be capable of holding a 5,000lb load if set well on a good bottom.

 

[Yahoo 1]

F anchor manufacturers charts.

Personally I always recommend going at least one size larger than any chart suggests.

Put out the biggest anchor you can all the time. Just to avoid these kinds of situations. Especially if you have a powered windlass.

Plus use some kind of anchor drag alarm in a location where you can hear it clearly.

Glad you made it out OK of a scary situation.

Well said. & an anchor drag alarm is absolutely necessary, so easy to use.

 

[Nomad Willy]

What is frequently overlooked is the standards that the size recomendations are written for. Very wide range here. Some I belive are rated for not much more than light breezes. Rocna rates for higher breezes of perhaps 40 knots. The best anchor size charts will give recomendations for several wind velocities. Some may not include enough positive bias for weight and even more wo'nt include enough. Thus there's a wide range of pits to fall into.

Whenever I read "get a size larger" l think of all the vessels that have relatively small anchors and most of them are old school w only 1/5 to 1/10th of the holding power of the newer anchors. Frequently these are commercial vessels run by professionals.

In a situation like the OP's almost always many here on TF will make big noises about getting a bigger anchor. It's easy advice that requires little thought. More often I think that evades the "problem". And if you actually do get a bigger anchor and it was a Rocna you'd have a really huge anchor. With other brands that rate for light breezes obviously getting a bigger anchor is or may be the right choice. It's always the right move to get an bigger anchor when you're anchor is too small but more often that's probably not the case.

 

[Waywego]

It seems to me that scope might have been an issue in your case. Manson recommends a minimum of 10:1 scope for 35 knot winds. Not knowing the height of your bow roller, I am guessing 5', giving you a vertical height of 17'. With 100' of chain out, you had a scope of under 6:1.


If there were any issues of bottom condition or poor set, that would only make the limited scope more of an issue. I think that the greater holding power at lower scope ratios of some of the current generation of anchors tends to give us false confidence in their abilities in heavier weather.


Then again, it never hurts to have a bigger anchor.

 

[dhays]

I am very happy that the OP was able to get out of a dicey situation with only a loss of sleep. Nice job Captain!

I have a 43' boat with a relatively large amount of windage. As I look at the sizing chart , I would have gone with a 60# anchor. As Manson says;

[FONT=Arial, Helvetica, sans-serif][FONT=Verdana, Arial, Helvetica, sans-serif]Finally the vessel usage should also be factored in ie whether the anchor will only be used as a "lunch pick" in fair weather for day outings or indeed whether the vessel will be going on extended coastal or offshore cruising. If in any doubt about anchor selection always use a bigger anchor, in bad weather or motoring failure, it is the only thing you can rely on to save the lives of you and your crew.[/FONT][/FONT]

Sure more scope would have been helpful, but you had better than 5:1 which I normally would consider adequate until the wind decided to kick up a lot.

Maybe the anchor wasn't well set? It did have an opportunity to soak quite a while so again, I would have thought it would have been well set.

Maybe 3/8" instead of 5/16" chain would be better? That is just getting way too picky.

I guess I am suggesting that I could easily have found myself in that same situation. No I don't use an anchor alarm most of the time either.

 

[ranger58sb]

One more possible problematic bottom would be mud. Chesapeke Bay-like mud that is very uncommon. If you review the Chesapke Bay mud test by Fortress Anchors you will see the only anchor that could have held your boat in a gale in that rare slimy type of mud would be a Fortress anchor.

Well... from that test.

I had hoped Fortress would have been able to include the SuperMAX in those tests, but they didn't, for various reasons. Think it would have done well, though, from my experience.

-Chris

 

[Waywego]

I guess I am suggesting that I could easily have found myself in that same situation.

+1 on that, though I suspect we would not have done such an excellent job getting out of trouble. Most likely, we would have been on the beach or have damaged our running gear.

It says a lot about you and your wife to have kept level heads and moved so quickly after just being woken up!

 

[sdowney717]

I am very happy that the OP was able to get out of a dicey situation with only a loss of sleep. Nice job Captain!

I have a 43' boat with a relatively large amount of windage. As I look at the sizing chart , I would have gone with a 60# anchor. As Manson says;


Sure more scope would have been helpful, but you had better than 5:1 which I normally would consider adequate until the wind decided to kick up a lot.

Maybe the anchor wasn't well set? It did have an opportunity to soak quite a while so again, I would have thought it would have been well set.

Maybe 3/8" instead of 5/16" chain would be better? That is just getting way too picky.

I guess I am suggesting that I could easily have found myself in that same situation. No I don't use an anchor alarm most of the time either.

Just finished reading this, idea is heavier chain wont help in a heavy blow, as it will be straight line from boat to anchor, no catenary which lowers the anchor shank down to the sea bed.

http://www.petersmith.net.nz/boat-anchors/catenary.php

 

[FlyWright]

Thanks for posting this, Bill. Glad to hear it all turned out OK. Sounds like you dodged a bullet with quick action by a competent crew.

I have to admit to becoming a bit lax about using an anchor alarm. Too many false alarms and I'm anchoring in relatively benign conditions, but I'm vowing to change that going forward. It's too easy for conditions to change from peaceful to terrifying.

Better to suffer a few false alarms than to have a crisis develop without warning.

 

[ranger58sb]

Just finished reading this, idea is heavier chain wont help in a heavy blow, as it will be straight line from boat to anchor, no catenary which lowers the anchor shank down to the sea bed.

FWIW, I think his "logic" is slightly flawed. Exacerbated by a couple graphs with the horizontal and vertical scales different... perhaps trying to subtly influence the reader visually as well.

OTOH, if he's just meaning to say "all other things being equal, heavier chain ain't gonna save your bacon" -- and trying to 'splain why that is -- OK, fair enough.

I can agree that catenary isn't an "only factor" involved. I can agree that catenary often disappears in heavy weather. OTOH, depending on wind speed, "disappearance" is often temporary. And catenary in slightly heavier chain would disappear less often. Doesn't mean heavier chain will solve everything, nor does it mean chain must always be REALLY HEAVY... but as one factor in in the whole anchoring system, there's a point where "Goldilocks" chain is a good thing.

That whole "depending on wind speed" is a moving, but critical, target... and impact of a given wind speed varies with both boat weight and boat windage. And chain weight. I think sustained winds that are heavy enough to cause catenary to PERMANENTLY disappear would vary from boat to boat and that would have to take chain weight into account.

-Chris

 

[Nomad Willy]

717,
Smith may want you to think his anchor is a substitute for chain. Or wants you to substitute chain for more anchor weight .. his anchor of course.

I'm not an avocate of lots of chain but to say chain dos'nt help is just not realistic. Unless we're talking about a very high holding anchor w light chain.

More chain will usually help IMO. However chain is most helpful during the early stages of anchor deployment especially during setting.

Putting chain weight into anchor weight always wins re ground tackle holding power per unit of weight. Anchor weight delivers more holding power than chain weight .. per pound.

 

[Nomad Willy]

Well... from that test.

I had hoped Fortress would have been able to include the SuperMAX in those tests, but they didn't, for various reasons. Think it would have done well, though, from my experience.

-Chris

Chris,
I was thinking the Max would be excellent in mud too and also disapointed the Max was'nt represented. Especially w the adjustable shank angle.

 

[dhays]

+1 on that, though I suspect we would not have done such an excellent job getting out of trouble. Most likely, we would have been on the beach or have damaged our running gear.

It says a lot about you and your wife to have kept level heads and moved so quickly after just being woken up!

Exactly!

 

[sdowney717]

I read his point is, if the storm wind is blowing so that the line is become straight, then the chain advantage regarding 'catenary' vanishes. Sure storms can blow hard and vary in wind strength, but some storms just blow hard long enough that the line stays ramrod straight a long long time, enough to drag on the 'other anchors' compared to his Rocna design. Maybe he is right.

My boat came with a Seachoice lookins like a Danforth and it suits me ok. We did drag one in a storm, the anchor did not set. The sand is packed there rock hard. Maybe the anchor dragged on it's side.

Eventually we were banging against Buckroe fishing pier. Owner of pier is panicking thinking my big boat will destroy his pier.
So anyway, we throw a line to them and they pull our boat around and we are free.

And we set the anchor and it holds. Cause if it did not, would have ended up on some old broken down pilings poking out from the water, and sure that would have doomed the boat.

Other thing is we ran out of fuel, called the USCG, they sent the VMP and gave us 5 gallons. I got one motor running and made it to the slip. He asked if there was less than $500 damage so he did not need to write a report, and I said absolutely.
And mostly I had to replace the upper railing off the flybridge, the antenna, and a piece of plywood that forms the right side of the flybridge.

It was a weird feeling, being in 2 to 3 foot waves, the boat moving up and down, and then the flybridge caught under the pier, the wave goes up and the boat does not.

Since I do my own work, it was an honest $250 repair I had to make.

This was before Hurricane Isabel in 2003 which destroyed that pier completely.

I was new to the boat, and coming back in less than a mile to the slip ran out of fuel cause I did not understand how much more it uses in foul weather and wind.

 

[ranger58sb]

I read his point is, if the storm wind is blowing so that the line is become straight, then the chain advantage regarding 'catenary' vanishes. Sure storms can blow hard and vary in wind strength, but some storms just blow hard long enough that the line stays ramrod straight a long long time, enough to drag on the 'other anchors' compared to his Rocna design. Maybe he is right.

Sure, fair enough, if sustained winds are that high, he can be right about those circumstances.

But sustained winds aren't always (or even often) that high. And in all those other times, maybe he is wrong.

A question for him might be: "When catenary exists, is it an advantage, yes or no?" And so forth.

-Chris

 

[dhays]

Interesting article. I find it a convincing argument under extreme conditions where the wind and current would completely straighten the rode.

However, I don't find myself in those situations. I do find situations where I have to use less scope than I might like. In that situation, the heavier chain does provide some more catenary and its improved shock absorption and improved shank angle.

 

[BruceK]

I am very happy that the OP was able to get out of a dicey situation with only a loss of sleep. Nice job Captain....

So many factors in each anchoring it is difficult to define what went wrong. If anything other than unexpected wind direction and strength. But worth analysis,for education and future prevention,for all of us.

 

[SoWhat]

Sometimes you get the bear, sometimes the bear gets you.

I don't think you did anything wrong, or I should say I would have anchored the same way. You were able to winch off so the anchor clearly can hold when bottom conditions are in alignment with the planets.

I think I might revisit the anchor alarm apps and make more of an effort to use them. Don't need any drama at 4AM.

 

[BandB]

F anchor manufacturers charts.

Personally I always recommend going at least one size larger than any chart suggests.

Put out the biggest anchor you can all the time. Just to avoid these kinds of situations. Especially if you have a powered windlass.

Plus use some kind of anchor drag alarm in a location where you can hear it clearly.

Glad you made it out OK of a scary situation.

+100. Larger anchor. Alarm.

Why so determined to get away from the Delta that came with the boat?

 

[ksanders]

Like others I think you just have to small of an anchor.

We run a 80lb "new generation" anchor on our 47' hull length boat as a comparison.

You've learned your lesson regarding anchor alarms.

Thanks for sharing

 

[ghost]

I bet you pulled out and reset since you could pull off. Sand was likely a big factor. Lots of things can occasionally cause an anchor to upset itself. I envision all of them when the wind starts blowing. Closer to the beach, you could even have set into a wavy bottom and inadvertently pulled through a high point. You never know exactly what the bottom looks like and sometimes you just get lucky.

Your scope should have been enough, especially with the shallow water. If your depth finder is off, that's going to have a big difference in that relative depth and could take a borderline situation in the wrong direction.

Also would be suspect of whether the chain was accidentally put down over the anchor. One thing I'm very particular about. I let the anchor touch bottom and wait for an indication of the chain to stop falling to let me know the anchor just touched. Then I sit and wait a moment, let the chain start naturally pulling a little before I slowly let out chain. All to ensure that I never drop chain over and anchor. Then and only then will I pay out extra length at a fast pace.

When the wind starts blowing, I've spent many a night sleeping sitting up with one eye out the window.