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Old 07-22-2016, 09:22 PM   #201
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I Will Pay The $$. Which Anchor Is Best?

Had a friend with a sailboat anchored in the Keys with a Bruce anchor. A thunderstorm came up during the night and the wind shifted 90 degrees. The Bruce turned, but before it could set it grabbed a chunk of coral the size of a basket ball. The anchor dragged and the boat was destroyed on the shoreline rocks. They escaped without injury.
I have questioned my tandem anchoring method. But after talking about his loss I am now committed to using two anchors in tandem, as I have without fail for the past eight years, to insure a safe night on the hook.
The Fortress goes in the water first, on an eight foot tether, followed by the Rocna on all chain. With the boat in reverse the two anchors have never fouled each other. In mud the Fortress is the first to hold. In grass the Rocna is the one that holds the boat. In most cases both are dug in. And a good nights sleep is had by all.
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Old 07-23-2016, 06:50 AM   #202
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I have questioned my tandem anchoring method. But after talking about his loss I am now committed to using two anchors in tandem, as I have without fail for the past eight years, to insure a safe night on the hook.
The Fortress goes in the water first, on an eight foot tether, followed by the Rocna on all chain. With the boat in reverse the two anchors have never fouled each other. In mud the Fortress is the first to hold. In grass the Rocna is the one that holds the boat. In most cases both are dug in. And a good nights sleep is had by all.

I've seen references to anchoring like that...

How and where do you attach the leading (first out) anchor to the trailing anchor (your Rocna) or the main rode? What's the tether made of?

(I guess when set they would have reversed those leading/trailing roles...)

-Chris
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Old 07-23-2016, 10:04 AM   #203
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In the Jan/Feb "Good Old Boat" mag there's an article by an individual tandem anchoring.

In a few hours I'll try to copy it and post.

My take on tandem anchoring is to use a good anchor the weigh of both anchors combined.


Ranger,
Probably to the trip line hole provided in the bottom of the shank of the Rocna for trip lines. Or perhaps tandem anchoring. I doubt the later as tandem anchoring is so uncommon. There are several threads in the past than can probably be searched.
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Old 07-23-2016, 02:38 PM   #204
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OK,
Here's the Good Old Boat magazine article.

Again I think if he had an anchor good at veering and reversing he'd be even better off w a 100lb anchor .. even a Claw. Combine the weight of both his 65lb and 35lb anchor for a 100lb anchor.

Was'nt an option for him as the 65lb anchor was his upper limit as he (like me) hand pulling was limited to a 65lb anchor. He's obviously stronger than me as my limit is about half that and I use little chain.

But for the average trawler one very big anchor would seem better. But there's a twin engine element here. If one anchor fails ?...........
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Old 07-23-2016, 08:22 PM   #205
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Quote:
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I've seen references to anchoring like that...

How and where do you attach the leading (first out) anchor to the trailing anchor (your Rocna) or the main rode? What's the tether made of?

(I guess when set they would have reversed those leading/trailing roles...)

-Chris

Most anchors, like the Rocna, have an anchor buoy hole in the forward end of the "Shank" which is opposite where you attach the chain rode. So I attach an eight foot 5/8" three strand line to my Fortress with an eye spliced on both ends and then shackle the other end to my Rocna buoy hole, going under the Rocna "Roll Bar". Pay out the Fortress first and when the eight foot line is out then continue dropping the Rocna on all chain, backing the boat during the process. Retrieval is easy. Raise the anchor chain until the Rocna is in the stowed position on the bow roller. Then reach over the bow rail and pull in the Fortress and stow it on the fortress clamp on mount.
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Old 07-23-2016, 10:14 PM   #206
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Quote:
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Most anchors, like the Rocna, have an anchor buoy hole in the forward end of the "Shank" which is opposite where you attach the chain rode. So I attach an eight foot 5/8" three strand line to my Fortress with an eye spliced on both ends and then shackle the other end to my Rocna buoy hole, going under the Rocna "Roll Bar". Pay out the Fortress first and when the eight foot line is out then continue dropping the Rocna on all chain, backing the boat during the process. Retrieval is easy. Raise the anchor chain until the Rocna is in the stowed position on the bow roller. Then reach over the bow rail and pull in the Fortress and stow it on the fortress clamp on mount.
Pgitug, my concern re the tandem approach is what happens when you anchor in situations where reverse current/tide always occurs. Does the Rocna ever foul the Fortress as it gets dragged past it..? Do they ever twist up..? Or do they hold so firm they actually don't reverse other than maybe the Rocna twists in the substrate at the first tide change, and becomes in effect, the only anchor. Unless the conditions were extreme, I suspect that might be what happens, in which cases maybe it would be simpler, and you would be just as secure, using the Rocna alone most times. Just a thought..?
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Old 07-23-2016, 10:36 PM   #207
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But Peter he says they never foul .. in 8 years of using this setup.

And it's a lot simpler that the system in the mag article.
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Old 07-23-2016, 11:12 PM   #208
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But Peter he says they never foul .. in 8 years of using this setup.

And it's a lot simpler that the system in the mag article.
I think that was my point Eric. If they have never fouled in all that time, when in the normal course of events, one anchor would have to be being dragged past the other as they re-set after a current/tide/significant wind shift, and during which you would surely expect the Rocna to pick up the line to the Fortress across its fluke once in a while at least, does sort of beg the question...is the Rocna, the second anchor, and therefore the one that would have to be dragged past the Fortress in that re-set, ever in fact doing so..?

Or, is it staying set, twisting round, or breaking out but re-setting so quickly it is in effect rendering the Fortress at the end of the connecting line, basically redundant..? One would never know. You can't see. But never fouling one on the other in all those years might be the only evidence that might be the case.

My respectful suggestion therefore to PgiTug, is to just leave the Fortress off a few times and see how that goes. What's to lose..? Psneeld does that all the time. Marin also. In fact everyone else that uses a Rocna I know of does just that. He may be going to that extra effort for nothing, even if he has it down to a fine art. Just sayin'
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Old 07-24-2016, 03:18 AM   #209
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I have questioned my tandem anchoring method. But after talking about his loss I am now committed to using two anchors in tandem, as I have without fail for the past eight years, to insure a safe night on the hook.
The Fortress goes in the water first, on an eight foot tether, followed by the Rocna on all chain. With the boat in reverse the two anchors have never fouled each other. In mud the Fortress is the first to hold. In grass the Rocna is the one that holds the boat. In most cases both are dug in. And a good nights sleep is had by all.
Interesting that you've been doing this for so many years, but wouldn't it be simpler to just buy one anchor of double the weight instead of the hassle of two smaller anchors?
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Old 07-24-2016, 06:05 AM   #210
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Here are tidbits on tandem anchoring

Two to Tandem: Maximizing Holding Power by Tandem Anchoring

Danforth types including the Fortress are shocking and are absolutely to be avoided. They are not general purpose anchors, and have no place in a tandem rig.

http://www.sailmagazine.com/cruising...andem-anchors/

Tangs or bolt holes provided for trip lines are seldom positioned correctly for attaching a tandem anchor, and as such they shouldn’t be used for this purpose unless the manufacturer indicates it’s OK to do so. The only anchor that has a dedicated attachment point for a tandem anchor is the Rocna. If you are tempted to add a tang or hole for attaching another anchor in tandem, consult the manufacturer first.
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Old 07-24-2016, 06:43 AM   #211
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Two to Tandem: Maximizing Holding Power by Tandem Anchoring

Danforth types including the Fortress are shocking and are absolutely to be avoided. They are not general purpose anchors, and have no place in a tandem rig.

I see it's Peter Smith saying that. Don't understand why, though. In the sentence above, he rails on a bit about anchors that have trouble setting... and then switches to beating up Danforth-style anchors as not being "general purpose" anchors. Guess that might depend on where, and the typical substrate wherever there is. Anyway, we've never had any problem setting our Fortress anchors, and they seem to be reasonably well-suited to this area.

(Might not work all that well on the coast of Tasmania or wherever he cruises, but then I don't expect to be there anytime soon... which means anchors that work well off the coast of Tasmania or wherever don't necessarily hold any extra attraction for our current boating adventures.)

@Steve Bedford: Comment on tandem anchoring with the SuperMAX? Built in trip line hole, looks to positioned well enough, on casual inspection...

In any case, I think I can't get enthused about the extra work, unless serious weather threatens. I like the "get a bigger primary anchor" idea, although I'm already probably up near the limit of what I can lift manually if the windlass craps out. And my pulpit -- at least on this boat -- might not take anything much bigger anyway.

-Chris
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Old 07-24-2016, 06:51 AM   #212
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Here is yet another published "expert"...this guy totally reverses the danforth tandem concept....

Anchoring 201

*The tandem anchor rig is a quick, easy way to increase the holding power of a single anchor rode by deploying two anchors on the same rode.**Stock-stabilized, pivoting fluke anchors (like Danforths) work best in this application, particularly in mud – U.S. Navy tests show use of tandem anchors increases total holding power by as much as 30 percent over the same two anchors if deployed separately.**These tests also showed holding power in sand increased only slightly overall when setting tandem anchors, most likely because the anchors themselves were designed for use in sand – in other words, use of a tandem rig closed the holding gap a bit between sand and the poorer holding quality of mud.

Any wonder why more and more boaters are skeptical of "published" marine experts?

As to Peter Smiths comments on danforths..I have come to the same conclusion about danforth style anchors.... BEST of the best for high holding, especially the fortress..but NOT a general use, all around, every day anchor. Before the gangup...I have 2 anchors for sale on Craigslist so I can go buy a Fortress as a stern, storm, backup anchor....I believe every cruiser should have one...but along with all the anchoring experts...there is no right answer....
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Old 07-24-2016, 07:23 AM   #213
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Quote:
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Here is yet another published "expert"...this guy totally reverses the danforth tandem concept....

Anchoring 201

*The tandem anchor rig is a quick, easy way to increase the holding power of a single anchor rode by deploying two anchors on the same rode.**Stock-stabilized, pivoting fluke anchors (like Danforths) work best in this application, particularly in mud – U.S. Navy tests show use of tandem anchors increases total holding power by as much as 30 percent over the same two anchors if deployed separately

As to Peter Smiths comments on danforths..I have come to the same conclusion about danforth style anchors.... BEST of the best for high holding, especially the fortress..but NOT a general use, all around, every day anchor.
I saw the Sail article said almost the same thing about the Navy tests, although apparently without knowing the Danforth-style was used.
"How much tandem anchors increase holding power is dependent on many factors, but tests conducted by the U.S. Navy reveal that tandem anchors set in mud increase the holding power by 20 to 30 percent compared to the same two anchors deployed individually. The increase in holding power is less marked in harder bottoms, such as sand. (Note: we don’t know what type of anchors were used in this test.)"
Seems to me a good case to increase the size of the anchor, but then again I know there's a max limit to the sizes makers offer... and single larger anchors for Navy ships might well be over that limit.

I think I don't disagree with Peter Smith's opinion that Danforth-style anchors might not be "general purpose" tools... but modified by quibbling a bit over the words "general purpose." If I were sailing the seven seas, I think I'd want more anchors on board that were maybe better for non-mud bottoms. OTOH, here in the Chesapeake, "general purpose" actually means "mud/hard mud/soft mud/slime/ooze/thick mud/grassy mud/muddy abandoned oyster reef/etc." and the Danforth-style (at least the Fortress versions that I've used) are about as "general purpose" as they come.

I'm coming to think that if I had to anchor out for a hurricane, I might choose the tandem approach (or that "hammerlock" thing looks interesting, and easier), with SuperMAX 17 as primary and FX-37 as secondary... perhaps both (but at least the FX-37) adjusted to the mud setting... instead of a Bahamian-like deployment... perhaps influenced by that Navy wording (probably paraphrasing)... and certainly influenced by those being the two proven mud-capable anchors that I've already got.


OTOH, so far, my hurricane plan has been to a) move to better floating docks somewhere (twice) or b) haul-out, if possible) in the time frame and if predicted storm surge probably wouldn't float us off the blocks. I think I still like these plans better than anchoring out somewhere an abandoning the boat to its fate.

-Chris
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Old 07-24-2016, 09:30 AM   #214
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PeterB,
Perhaps the Rocna just has'nt dragged. They are after all a very good anchor.
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Old 07-24-2016, 09:43 AM   #215
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As I stated earlier. The sole reason for using a tandem anchoring system is for the off chance that your Rocna type anchor fouls on a round piece of coral or picks up a crab trap while trying to reset. And yes, I do think there are a few lost crab traps out there. So if you have an oversized anchor for insurance, you still have the one off chance of having that big heavy anchor picking up a crab trap when the wind shifts and the anchor begins it's new direction reset. I can guarantee you that if the pointy end of your anchor snags a half buried crab trap it is not going to set. And your boat is now a drift while you slumber. What are the chances of that ever happening??? It happened to my friend as previously stated. I just want to know that I have done everything to insure that it does not happen to me. Everybody for their own reasons have different anchoring methods. Tandem anchoring is mine.
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Old 07-24-2016, 09:59 AM   #216
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As I stated earlier. The sole reason for using a tandem anchoring system is for the off chance that your Rocna type anchor fouls on a round piece of coral or picks up a crab trap while trying to reset.

Fair point. We picked up what looked like a 3' x 3' piece of roof shingle a couple weeks ago, and we did drift a bit overnight, I think about 40' or so.

(Believe it didn't happen when we originally set the anchor, but during some maneuvers we tried to make while still anchored in order to aim our loudhailer at the 18-boat raft behind us, with their music turned up loud enough so everyone in the county could enjoy it. Local water police eventually solved that, probably in response to calls from everyone anchored in the creek and especially the local homeowners.)

Anyway, it was wrapped over the middle fluke and one of the outside flukes. Looked like the effect was to create a big round ball of mud, two out of the three sharp points blunted. And it seemed like we brought up about twice as much mud as usual when we weighed anchor.

I had to futz with a boathook to get the shingle (or whatever it was) to come loose.

I could see where a second anchor could have mitigated that...

-Chris
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Old 07-24-2016, 02:14 PM   #217
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Here is yet another published "expert"...this guy totally reverses the danforth tandem concept....

Anchoring 201

Ummm... that ref includes this:
When preparing a tandem rig be sure to attach the second or aft anchor rode to the forward anchor’s crown rather than its ring...
Which do we think is "aft"?

Why be attaching a secondary anchor rode directly to another anchor? Instead of to the other anchor's rode? (Except perhaps in the Rocna example, where that seems to be quite appropriate.)

??

-Chris
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Old 07-24-2016, 02:22 PM   #218
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Ummm... that ref includes this:
When preparing a tandem rig be sure to attach the second or aft anchor rode to the forward anchor’s crown rather than its ring...
Which do we think is "aft"?

Why be attaching a secondary anchor rode directly to another anchor? Instead of to the other anchor's rode? (Except perhaps in the Rocna example, where that seems to be quite appropriate.)

??

-Chris
Who knows...half of these guys are probably better writers than boaters.

I can understand the one reference that unless the manufacturer supplies a recommended hole on the anchor to attach another anchor to....then best add it to the rode.

I surmise that is so when the lead anchor digs, it doesn't change the angle of the anchor closer to the boat.
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Old 07-24-2016, 02:28 PM   #219
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Weight affects a lot of elements of performance beyond fuel burn.

Weight can have a profound effect on trim that can have positive or very negative effect on turning and ultimately boat control can be lost in certian circumstances.

Weight as an excess is always bad.
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Old 07-25-2016, 06:54 AM   #220
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"@Steve Bedford: Comment on tandem anchoring with the SuperMax? Built in trip line hole, looks to positioned well enough, on casual inspection..."

There is a "trip line" hole on the opposite end from the rode hole that could indeed be used in a tandem arrangement with the Super Max Anchor. However, tandem anchoring is just one option for arrangement when the decision is to use multiple anchors. If using more than one anchored and each anchor has its one rode terminating on th vessel, you are actually considered to be moored.

Rudy and Jill Sechez, in their excellent book (no affiliation), Anchoring, A Ground Tackler's Appentice advocate, and I agree, state that the ground tackle for each anchor should be based on the "Big 5." These are size of the anchor, the design of the anchor for its intended purpose, the strength of the components, the desired scope, and chaife protection.

Whatever method of multiple anchors the captain chooses, one should not "assume" that two anchors with marginal specs regarding the "Big 5" will be sufficient. Instead, each anchor and its accompanying ground tackle should be sized sufficiently to safely hold the vessel under normal conditions. Remember, if one anchor gives way, you are on that one remaining anchor. If it is undersized, you may have a serious issue.

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