Tandem anchors

[seaotter]

Hi all,
After a 2 am fire drill when the wind came up and I had several boats rafted to me I working on increasing holding power in a 50,000 lb power boat.

As a single hander I need equipment that is well thought out and easy to handle in unfriendly conditions.

I'm looking at hooking a spare 45 lb cqr to my main rode (3/8 chain) about 40 feet in front of the main anchor. Since the cqr would come over the roller first on retrieval I need an easy way to unclip it from the main rode.

I'm loathe to trust carabiners and I don't like the way they load the main rode. So far my best answer is just tie the cqr on with about 15 feet 1/2 nylon braid using a rolling hitch.

Thoughts appreciated .....

Jim Slocomb
Friday Harbor

 

[Nomad Willy]

seaotter,
some thoughts;

I'd change the CQR nearest to the boat for a Claw as they have good short scope performance.

What is your 2nd anchor?

Do you set them one at a time or just back down until one sets and leave it at that?

I'd consider 2 rodes and set each anchor by itself.

If you swing even a fairly small amount all the load will be on one anchor.

Choose anchors that set very dependably.

Choose an single anchor w more holding power than the 2 that your'e using now.

Search tandem anchoring. We've already been there done that.

Tell your friends to get their own anchors.

 

[Captain K]

I agree with "manyboats" suggestion for using two anchors on two rodes. This may appear to present a problem if, like me, you have only one bow roller. But if you use a snubber on your chain rode, you can easily run it through a bow chock instead of on the bow roller. That frees the roller to retrieve your secondary anchor. Once that's aboard, move your primary anchor back to the roller and bring it in. I've never tried the tandem anchor bit, but second hand comments from friends lead me to believe it can get pretty well tangled with a change in wind or current. Good luck!

 

[Steve]

"As a single hander I need equipment that is well thought out and easy to handle in unfriendly conditions."

I have never tried it but I can't imagine anything less userfriendly than two anchors on the same rode, especially when single handed.

I'd try other sizes or styles.
Good luck.
Steve W

 

[Larry H]

Hi Jim,

Having seen the massive hydraulic reel windlass on Sea Otter, why not just get a bigger anchor, or one with more fluke area?

 

[FF]

Frequently simply installing the deck gear to handle a larger anchor will do what you need.

A 60H Danforth , that could be swopped for a 90 Danforth ,

or 90 plow that could be swopped for the next size up would be my choice.

BIG anchors work better in Iffy bottoms than small anchors.

When someones, this weeks ,home brew "super wonder anchor: has 60 years of excellent service , as these do, they might be a consideration.

Tandem anchors are a desperation move when caught out and have no choice .

Anchors spread out in a V are not that easy for a single hander to get back aboard,

BUT if your windlass id over sized and HYDRAULIC , its not bad at all.

The windlass must be able to do non standard operation, drag the boat up to an anchor and yank it out .

With good sized anchors, (90lbs +) a boat hook and a location ball or fender with a line tied to the crown makes it a lot less effort.

 

[Nomad Willy]

Hi Larry. Chris and I were just talking about you yesterday.

Re FF hydraulic is great but electric is fine if not overworked. And nobody should expect their winch to "drag the boat up to an anchor and yank it out ." If that's what FF is actually doing he DOES need a big hydraulic winch. Pulling boats is light duty stuff unless in big wind and my very small electric winch has worked fine so far. But I use the anchor cleat and the boat w it's engine to break out a deeply set anchor.

I agree that the OP should probably get a great big Claw but if holding power is of the greatest importance then FF is absolutely wrong. The newer anchors do indeed have greater holding power but most require a longer scope. If I know it's going to blow 60 I'll not be getting out my Claw, Dreadnought or Danforth but my XYZ or Manson Supreme.

But the OP will probably do just fine w a big (for him) Claw.

 

[FF]

Re FF hydraulic is great but electric is fine if not overworked.
And nobody should expect their winch to "drag the boat up to an anchor and yank it out ."

I travel with the bride , so crawling up at idle and letting the vessel break out the anchor , as normal , is our choice.

The bride is an ex sailor , so has zero problem tailing as we recover the rode.

The gear and equipment required for a SINGLE HANDER to safely operate a vessel may require gear and techniques that are out of the "normal" crewed boat range.

In most anchorages the wind is so light (thats why you chose a sheltered area to anchor) that hauling the boat TO the anchor is a minor task, just requires the windlass to operate at minor load , but for a Longer time.

IF the wind is light the boat may have enough momentum to unset the anchor as it goes over top.
Then the single hander only has the question of how far and fast will he be blown back, before the anchor is secured and he can regain the helm.

The fear is an electric unit will not have a long enough ON time before overheating.

Different strokes for vastly different operation requirements.

 

[boatpoker]

I have used tandem anchoring three times in high gales, one of which lasted three days (no sleep). The primary rode is run through a large stainless steel caribiner at the secondary anchor so the secondary anchor acts as a large kellet keeping the primary rode horizonatal on the bottom. I had no problems with tangled rodes due to tide or current changes. In previous storm conditions I put out two separate rodes and always had a tangled mess to deal with.

 

[Chrisjs]

From what I have read, two anchors on the same rode is not recommended because the anchor nearest to the boat is hard to set properly and can be lifted out relatively easily, and can actually contribute to unseating the primary anchor. I think this presumes that the scope on the nearer anchor is necessarily significant shorter than on the primary anchor. Boatpoker seems to address this issue by recognizing that his secondary nearer anchor is really acting more like a kellet, and if it stays stuck in the ground so much the better. I think the real answer to the original question is for more boats (in the middle of the raft) to lay down their own (large) anchors with adequate scope. Obviously the more hardware in the water, the greater the risk of tangling!!

 

[Nomad Willy]

Poker,
That's a great idea. I made a 12lb Kellet for Willy (30' boat) and see by your example I cou'da saved my time and just used another anchor instead. All are considerably heavier too.

Are you tandem anchoring or using the 2nd anchor as a Kellet?

I don't see any in your drawing but does the 2nd anchor have a bit of rode after the caribiner? One could adjust the scope of the main anchor in such a way and/or take some load off the 2nd anchor if indeed it's being used as an anchor and not as a Kellet.

I assume you set the primary anchor first. Then w a little rode of it's own the scope of the primary anchor could be controlled ..... but basically only if it was set.

Ideally both anchors would be set w the perfect length of rode for the 2nd anchor so both would reach their breakout moment, tension or/and angle of scope at the same time. Would be dependent on the wind not changing direction much but in high winds that's been my experience anyway.

This system could have a lot of holding power for having all parts of the ground tackle light enough to easily handle.

We've had tandem anchoring discussions before and I don't recall this method emerging then. I like it.

Chrisjs,
We were posting at the same time ... and haha much the same thoughts. But how would the secondary anchor help "unseating" the primary? I can only see it helping the primary stay set.

 

[Rambler]

"As a single hander I need equipment that is well thought out and easy to handle in unfriendly conditions."

I have never tried it but I can't imagine anything less userfriendly than two anchors on the same rode, especially when single handed.

I'd try other sizes or styles.
Good luck.
Steve W

Yeah. I'm thinking that I'd get the rode up and working on the "second" anchor whith the primary anchor hanging so many feet below the water and my boat drifting at will.

Two anchors on two rodes.

Oh, and make the other boats in your raft group toss their anchors out too. I doubt many boat anchor systems are designed to hold for a two or three times the boat weight.

 

[Nomad Willy]

On further reflection I'm think'in it's too complicated to tandem anchor this way but w the 2nd anchor acting like a big Kellet would go a very long way to optimizing the catenary and effective scope of many anchors. Especially those that loose a lot of holding power at short scope. With a medium sized anchor hang'in on the rode it would take a lot of wind to straighten out the rode and extinguish the catenary.

I see this as advantageous in another way too. Short scope anchoring in small anchorages. Would reduce swinging dramatically.

 

[boatpoker]

Poker,
That's a great idea. I made a 12lb Kellet for Willy (30' boat) and see by your example I cou'da saved my time and just used another anchor instead. All are considerably heavier too.

Are you tandem anchoring or using the 2nd anchor as a Kellet?

I don't see any in your drawing but does the 2nd anchor have a bit of rode after the caribiner? One could adjust the scope of the main anchor in such a way and/or take some load off the 2nd anchor if indeed it's being used as an anchor and not as a Kellet.

I assume you set the primary anchor first. Then w a little rode of it's own the scope of the primary anchor could be controlled ..... but basically only if it was set.

Ideally both anchors would be set w the perfect length of rode for the 2nd anchor so both would reach their breakout moment, tension or/and angle of scope at the same time. Would be dependent on the wind not changing direction much but in high winds that's been my experience anyway.

This system could have a lot of holding power for having all parts of the ground tackle light enough to easily handle.

We've had tandem anchoring discussions before and I don't recall this method emerging then. I like it.

Chrisjs,
We were posting at the same time ... and haha much the same thoughts. But how would the secondary anchor help "unseating" the primary? I can only see it helping the primary stay set.

Sorry, I thought my diagram was better than it is. We Drop our primary anchor and set it, then shorten up the rode (say 75') We launch our secondary anchor with the caribiner enclosing the primary rode, We then run out the second rode until tha anchor is on the bottom, then drift back letting matching amounts of rode out, Then drive in both anchors. Once they are set we can shorten or lengthen rodes together as needed. Retrieval (with a horizontal windlass) pulls both rodes back together. When the caribiner is within reach we disconnect it and complete retrieval.

We practiced this a few times to get comfortable with it but after the high gales we think we'll stick with it.

 

[FF]

Perhaps just a HEAVY kellet , say 75 lbs would help keep the anchor angle aimed right and provide a good surge damper.

Fairly easy to set/lift a lump of lead .

I would use a special rode shoe to keep the kellet attach point from eating the anchor line.

I have seen a few boats that had a very hard time staying anchored because the anchor line was way too heavy , so there was no shock absorbtion by the line.

20lb anchor 5/8 nylon.

Like being anchored with a steel cable , passes huge shock loads to the anchor if the boat veers in the wind..

 

[Nomad Willy]

Steel cable FF? I thought my "Brait" was nylon.

Some time I'll string out a 30' section of my 5/8" Brait and compare it to a 1/2" 3 strand nylon of the same length. You tend to exaggerate things but you've mentioned this many times so I'll see for myself.

I suspect the 1/2" is about 25% more "stretchy" than the 5/8ths.

 

[seaotter]

Thanks all for the good discussion.

For those who asked my primary anchor is a 100 lb davis seahook that has been modified to add points and a lot of fluke area. It now weighs about 130 lbs.

The idea of hanging the cqr more as a kellet than a tandem anchor is interesting. I'm going to play with that idea.

I should have said in the original post that I had about 300 feet of chain out in 45 feet of water and that that is the scenario I envision using the tandem setup in. Stated other wise ... main anchor goes over the bow and about 20 feet of chain. Then strap on the cqr and let out more scope till your in the 10 to 1 category.

I think a good test will be to go back to the same area on a calm day and see just how much power I can apply in reverse before things start to move. That would give me a bit of a metric as to differences in holding for the various configurations.

Thanks again
Jim Slocomb
Se Otter
Friday Harbor

 

[Nomad Willy]

Seaotter,
I'm going to better that next summer. I'm going to put a bridle on my stern cleats that will be tied into my ctr stern cleat and pull at full throttle in FWD gear. Before you say holy crap you should know that's only 40hp and an 18" prop but it's good for almost 1000lbs of thrust.

The 900lbs (or so) of thrust will be more force than a 70mph wind I think. Any anchor that could handle full power in fwd gear should hold the boat without question (except for bottom type and condition) in any wind "imaginable". With the bigger engines of most boats on this forum it should be more true for most everyone else here.

Anybody seen the Manson "Boss" anchor yet? Looks more like an airplane than an anchor to me. With that "tall" shank and clean fluke it should penetrate really good. Could be the best anchor yet for holding power.

 

[jeffnick]

Instead of the extra gear for a kellet or tandem anchor, wouldn't one be better off just using a single anchor of the combined weight? When the rode fetches tight, isn't the anchor doing the holding...not the all chain rode or kellet? It seems to me these tactics, while effective in exaggerated conditions, do not address the ultimate condition where the rode is a straight line to the anchor?

 

[Nomad Willy]

Jeff I've always advocated putting the bulk of the ground tackle weight in the anchor. It's the only thing that makes sense.

But there are times when tandem anchoring could be of great benefit. My boat is 30' and 16000lbs disp. The usual serious anchor weight recommended by most authorities will fall in at around 30 lbs w another 30 lbs of chain. Sixty pounds of rode is just too much to pull for most people. In my case (that led me down an interesting trail) I tried to find a 15lb anchor that worked as well as a 30lb anchor.

But w two 15lb anchors one would think there would be a possibility that one could tandem anchor as effectively as w one. But what one can think and do are frequently not the same. A 15lb Kellet on a 15lb anchor will not equal the performance of a 30lb anchor but it would quite likely increase the capabilities of the 15lb anchor to the level of a 22 or even a 25lb anchor but not coming close to the lifting effort required for retrieving a 30lb anchor.

And if the Kellet was actually an anchor .. and it was set ..

 

[Chrisjs]

I think the function of the primary anchor and the kellet are different. The primary anchor should be heavy enough to stay put in the bottom under adverse conditions. However, this largely depends on the length and weight of the scope. Obviously heavier scope (chain) will protect the anchor more than light (nylon line), and longer is obviously better than short. To my mind, the function of the kellet is to add weight to the scope and to try to help keep the pull on the anchor as horizontal as possible. Increasing the weight of the primary will probably help it stick firmer but not necessarily make up for inadequate scope weight or length.

 

[psneeld]

Instead of the extra gear for a kellet or tandem anchor, wouldn't one be better off just using a single anchor of the combined weight? When the rode fetches tight, isn't the anchor doing the holding...not the all chain rode or kellet? It seems to me these tactics, while effective in exaggerated conditions, do not address the ultimate condition where the rode is a straight line to the anchor?

Even though my anchor is one or even two sizes bigger than recommended for a storm anchor...there's a distinct PROBABILITY it will never see anything more than a steady 25 knots in protected waters except for the occasional thunderstorm gust.

It's likely my boat will never see all the chain lifted off the bottom.

So for many cruisers...talking bar tight anchor rodes is like talking fire or sinking. Not something you expect eevn though it's a remote possibility.

World cruisers or just those that purposly "stick their nose in it" have to worry...not me...spent a long career of rescuing boaters....have no wish to be at the other end of that hoist cable...

 

[Marin]

My boat is 30' and 16000lbs disp. The usual serious anchor weight recommended by most authorities will fall in at around 30 lbs w another 30 lbs of chain. Sixty pounds of rode is just too much to pull for most people.

You're assuming most people retrieve their anchor and rode by hand. I think you will find that most people who own boats like most of us have on this forum have windlasses, either powered or manual. As such, it doesn't matter how much your tackle weighs as long as the windlass can handle it.

There is the issue of what to do if the windlass fails. If it simply won't run, the obvious solution is to have a windlass with a manual retrieve method as a backup. Our Tigres has this as do a lot of other electric windlasses.

If the windlass lunches a gear or two--- it happened to us with the no-name horizontal windlass that came with the boat---- that can present a problem if the anchor and rode are too heavy to retrieve by hand. But I believe that unless one has a poorly made windlass or severely overloads their good windlass this possibility is so remote as to be all but ignored.

 

[Phil Fill]

Anchors again? Another discussion pops up?

As stated before I still believed in having multiple types of anchors depending the weather, depth of water and the bottom. The best tool I have found is by FF http://alain.fraysse.free.fr/sail/rode/synthesis/synt.htm Which allows you to change the conditions and variables. According to the formula, in 90+ MPH, hopefully never happen, wind, 50 ft of water, a 140 lbs anchor with a 250 ft chain scope would be required. However, the present old windlass and my WIFE can not handle a 140 lb anchor and 250 ft of chain. However, the present 60 to 70 lbs anchors with 4 times all chain scope is good to 40 mph which the windless and wife can still handle. According to the formula increase the scope is almost as good as increasing the weight of the anchor. Also the bottom holding power is a huge factor, and reducing the swing, so its not just the anchor.

Since we carry 3 different/types of anchors, old school, with two rode’s, 200 ft all chain and 50 ft chain with 200 ft of rope, the idea of tandem anchors would be the next step if conditions require. With the tandem the secondary anchor has to weight less that what can be handled/carried/lifted However, I was going to connect the rode of the primary anchor to the secondary anchor, rather than two separate rodes as illustration shows. I still can not figure out how to retrieve two all chain rodes at a time?

It would be a lot cheaper to replace the windless for about 3 grand vs. the wife several hundred grand. I can not afford a new WIFE.

 

[psneeld]

You're assuming most people retrieve their anchor and rode by hand. I think you will find that most people who own boats like most of us have on this forum have windlasses, either powered or manual. As such, it doesn't matter how much your tackle weighs as long as the windlass can handle it.

There is the issue of what to do if the windlass fails. If it simply won't run, the obvious solution is to have a windlass with a manual retrieve method as a backup. Our Tigres has this as do a lot of other electric windlasses.

If the windlass lunches a gear or two--- it happened to us with the no-name horizontal windlass that came with the boat---- that can present a problem if the anchor and rode are too heavy to retrieve by hand. But I believe that unless one has a poorly made windlass or severely overloads their good windlass this possibility is so remote as to be all but ignored.

Exactly Marin..and if I didn't have a windlass or if it failed...I would use some sort of block and tackle arrangement to haul in my appropriately heavy ground tackle (which doesn't have to be that heavy cause i'm never anchoring in that much of a blow ) ..

I can't believe there is all the experience in this forum yet so many never think an inch out of the box....

 

[Phil Fill]

Exactly Marin..and if I didn't have a windlass or if it failed...I would use some sort of block and tackle arrangement to haul in my appropriately heavy ground tackle (which doesn't have to be that heavy cause i'm never anchoring in that much of a blow ) ..

I can't believe there is all the experience in this forum yet so many never think an inch out of the box....

Actaully I carry extra anchors and rode so if we have to cut loose one we have a spare. During a sudden wind storrm I cut the chian and let go with a bouy connected. Came back the next day to retrive. Also anchors can be used to careen/tip the boat and/or keep up ride if a ground. There are more uses for an anchor than anchoring.

Our windless has holes so pipe/bar can be stuck into so can be manual if the windless stops and/or can not handle the load. I have used the mast and boom electric winch to retrived the stern anchor before. I guess it would work for the bow also. ?

 

[jeffnick]

So for many cruisers...talking bar tight anchor rodes is like talking fire or sinking. Not something you expect even though it's a remote possibility.

World cruisers or just those that purposly "stick their nose in it" have to worry...not me...spent a long career of rescuing boaters....have no wish to be at the other end of that hoist cable...

You make me smile.


We lived aboard for 3 years, probably spending less than a month total tied to a dock. We weren't world cruisers, but we did spend at least 6 months a year away from our home port. During our time aboard some things became apparent.

A cheap battery was good enough - we could always hand start the little diesel.

A better set of sails was was what we needed for the cruising we did.

But good and better weren't considered for ground tackle - it had to be the best and ready for the worst.

We started with the much touted, bulletproof, all chain rode. It wasn't long before we became aware that if we put the chain weight into the anchor itself we'd be better off, especially after experiencing a 'bar tight (chain) rode' that jerked the daylights out of everything/everyone aboard when it fetched up. There have been many, many posts here about snubbers, but I just couldn't bring myself to complicate things that way, so we opted for 100% nylon rode.

Then we got into the kellet/multiple anchor thing, which meant more complications so we just got a bigger anchor.

By now, the anchor was too big to manage by hand. Not wanting to indulge in complicated windlasses, we opted to go with a manual rig. Now that we didn't have any stubborn, gypsy jamming, mud catching chain to contend with, a simple capstan could be used. We opted for a 2 speed sheet winch.

With a couple wraps, the winch would only allow line to be pulled in...it would not go backwards. There is a long handle that locks into the top of the winch. When you turn the handle one way, the capstan turns at a 1 to 1 ratio. Move the handle in the other direction it takes 3 turns for one turn of the capstan. This simple piece of gear made anchoring a pleasure.

I guess if you only anchor occasionally, you view kellets, all chain rode and snubbers as a viable alternative, but when you live aboard, dropping the hook regularly, it's got to be simple and right.

And I've mentioned before, just because your ground tackle is keeping you put, doesn't mean you won't have to get it up in a hurry when someone is dragging down on you and any extra junk you attach to your anchor will complicate getting it up at a time when you most wish it was simple and easy.

 

[Nomad Willy]

"You're assuming most people retrieve their anchor and rode by hand."

No Marin I think I made that clear in post #20

I'm well aware most everybody uses a winch.

 

[Marin]

doesn't mean you won't have to get it up in a hurry when someone is dragging down on you and any extra junk you attach to your anchor will complicate getting it up at a time when you most wish it was simple and easy.

It continues to amaze me how many people here who have all-chain rode talk about how they'd cut the chain if they couldn't get the anchor up or have to leave without getting the anchor up. I can't think of anything slower or more silly than trying to cut a piece of chain when you're in a hurry.

We learned--- probably from Earl Hinz's book--- to attach a length of stout line between the last bitter end link of anchor chain and the big eyebolt in the ceiling of the chain locker that's meant for securing the bitter end of the rode so it won't all go overboard in the event of a wildcat failure.

The line is cut long enough so that it will appear on deck when all the rode is let out. So letting go the anchor and rode in a hurry is simply a matter of letting it all out and then taking the line cutting blade on one's Leatherman and cutting the line on the end of the rode with a couple of swipes.

The one time we came close to doing this was when we were being blown onto a lee shore with a dragging anchor. The original windlass to the boat was agonizingly slow and it became apparent we'd have to let the anchor and rode go so we could get the hell out of where we were. I figure that by the time it became apparent we'd have to do this we had perhaps a minute before the boat would be ashore. Trying to cut the chain with a saw would not have solved our problem.

Cutting the line connecting the end of the chain to the boat would have.

 

[Phil Fill]

I carry large bolt cutter, so not a problem. Being a live aboard we have most tools/things that might be reqired. Besides its an anchor vs the boat and safety. The end is tied to 2x4 with a rope.