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19-04-2018, 17:53
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#1
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Registered User
Join Date: Nov 2012
Location: Sydney
Boat: Alubat Cigale 16 16.4mt
Posts: 18
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Tandem anchors for storm conditions
Would like to hear input from those who have ridden out a storm or heavy conditions utilising 2 anchors in tandem or thought about it. Example is to have main anchor set on regular chain at appropriate scope and to have another anchor attached to that and is set first. I expect the front anchor is smaller than main anchor and is mainly to share the load as main anchor comes under strain and to prevent or slow down dragging and thereby enabling main anchor to reset. Discuss the length of chain between the 2 anchors. Is it smart to buoy main or tandem anchor My main anchor is a Sarca Excel, do I use a similar type but how much smaller? This appears to be simple to set up in a hurry and logically could provide very secure anchoring. In the past I have set 2 anchors at 60-70degs separation with some success but i think this setup is fraught with many more possible problems. Be great to hear your thoughts and perhaps someone out there has had experience.
I sail a 52' Alloy cutter on the East coast Australia, Tasmania, NZ and South Pacific. Regards popeye
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19-04-2018, 18:08
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#2
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Marine Service Provider
Join Date: Jul 2014
Posts: 6,103
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Re: Tandem anchors for storm conditions
Tandem Anchors?
Two to Tandem: Maximizing Holding Power by Tandem Anchoring
“ Most boaters should never have cause for tandem anchoring. Your primary anchor should be sized so that it is adequate on its own in practically all conditions – if it is not, then upgrade. [The tandem anchoring] functionality is provided for those more ‘extreme’ adventurers who require it.”
See the linked page and site for more opinion from Peter Smith (ROCNA)
http://www.petersmith.net.nz/about/
If you don't already know about Peter Smith, I suggest reading his bio profile, and notice the boat he built and used for travels in some hazardous areas.
Kiwi Roa
52' Aluminum expedition yacht
http://www.petersmith.net.nz/about/kiwiroa.php
______
Bottom line: I respect his experience and opinion.
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19-04-2018, 22:02
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#3
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Registered User
Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,433
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Re: Tandem anchors for storm conditions
Tandem anchors is a common practice in the offshore petroleum industry. They use a pennant between the anchors long enough to allow the second anchor to be retrieved before the primary, and a buoy and pennant from the crown of the second anchor to allow it's retrieval.
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20-04-2018, 00:11
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#4
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Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 9,569
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Re: Tandem anchors for storm conditions
Try it. Set two anchors, then change the direction of pull by 20 degrees and watch the near anchor roll-out. Look at Peter Smith pictures; you can see the anchors are not buried and are starting to lift out. He did not show a change in direction. In other words, they were staged.It only works when the bottom prevents proper burying, such as hardpan and cobbles.
Even the platform guys do NOT recommend this anymore. Note that none of the other anchor manufactures agree and that none provide holes for this. Spade has said "don't do it." Only Peter Smith seems to think it works. Think about how they claim that all of the angles are critical, and then think how much the back-tension changes all of the angles.
Try it. Set the anchors, then pull to the side, then dive and see what's up. I have, many times.
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20-04-2018, 00:38
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#5
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Registered User
Join Date: Dec 2009
Location: Bundaberg, Qld.
Posts: 2,192
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Re: Tandem anchors for storm conditions
Quote:
Originally Posted by RaymondR
Tandem anchors is a common practice in the offshore petroleum industry. They use a pennant between the anchors long enough to allow the second anchor to be retrieved before the primary, and a buoy and pennant from the crown of the second anchor to allow it's retrieval.
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That is one way we can do it but there are few easier ways, but we only use any tandem set-up for straight pulls.....
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20-04-2018, 02:15
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#6
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Registered User
Join Date: Mar 2011
Location: Panschwitz, Germany
Boat: Woods Mira 35 Catamaran
Posts: 4,235
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Re: Tandem anchors for storm conditions
Hi,
on our cat I did not do tandem, but did often set a second anchor with a slightly slack rode from the other bow, in the hope it would take a bite should number one fail.
It has worked for me on two occasions.
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20-04-2018, 08:18
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#7
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Registered User
Join Date: Feb 2017
Posts: 28
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Re: Tandem anchors for storm conditions
I used anchors in tandem In the Sea of Cortez during hurricane
"Lester" in 1992. I had a Danforth 50' of chain then CQR plow
with 150' chain and 50' of rode. We rode out "Lester" well trough
both sustained winds and gusts behind Isla Ventana.
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20-04-2018, 08:21
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#8
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Registered User
Join Date: Sep 2007
Location: Delray Beach, Fl
Boat: 1998 Rosborough 246 LSV
Posts: 563
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Re: Tandem anchors for storm conditions
I always said tandem anchors when expecting heavy weather.
In hurricane Wilma I set a 50 kg Bruce on 100 feet of chain in 8 feet of water with two bridles, my normal 5/8 bridal off of the two hills Of my voyage 43 cat, and a second storm anchor attached to the chain Rollinghitch set midships also using five eights line.
Off the trip point of the manufacture provided Bruce, I sent 8 feet of 5/16 H teaching, the same chain are used for the primary. Of my voyage 43 cat, and a second storm anchor attached to the chain Rollinghitch set midships also using five eights line.
Off the trip point of the manufacture provided Bruce, I sent 8 feet of 5/16 HT.chain, the same chain are used for the primary.
The veer of Wilma passed over my boat causing it to run down the chain and break both bridals when it reset on the secondary anchor, and FX 39 fortress.
When the second anchor sex or reset, both the shanks and the flukes back to uselessness but the anchor held.
With the 2 5/8” bridals broken The load was taken by the winless which promptly broke the mounting board. I fortunately tied an overhand not in the chain that jammed in the hwade pipe after breaking her heartpoint But the better end of the road was shackled to.
When the overhand knot jammed in the hawse pipe, The chain stretched uselessness but held.
Fortress replaced all the bent parts under warranty, I rebuilt the winless base and reattach the winless, replace the chain, and made two more bridals.
The other 50 or so Boats in the Anchorage were all lost. Or Severely damage. There is no way to determine if another way of anchoring would’ve held however the tandem anchors are used did hold and save the boat even though I clearly reached the limit of the chain ground tackle an attachment points.
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20-04-2018, 08:36
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#9
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Registered User
Join Date: Dec 2013
Location: Fort William, Highland, Scotland
Boat: Bavaria Cruiser 40
Posts: 917
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Re: Tandem anchors for storm conditions
Buy a bower anchor big enough to hold you safely in a hurricane with enough chain (or chain and rode) to set out at least 5:1 (even as much as 10:1).
Don't bugger about trying to set 2 anchors or complicate matters because when you drag in a storm you don't want to be handling more metal than you need to.
If you want to double up then set in a V with a secondary anchor capable of holding you on its own on a separate rode.
I have a 33kg Vulcan on 60m of 8mm G70 spliced to an additional 45m of 16mm Octoplait. On a 40ft Bavaria Cruiser. My old 16kg Delta is purely on board as an "oh F!" emergency lump in the unlikely event I have to drop my bower.
Never heard of any rig using tandem anchors as we normally have 8 to 12 huge Bruce anchors set out 2 or 3 to the corner. Or in deeper water we just use GPS and thrusters to maintain position.
Keiron
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20-04-2018, 08:41
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#10
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Moderator
Join Date: Sep 2014
Location: Channel Islands, CA
Boat: 1962 Columbia 29 MK 1 #37
Posts: 14,305
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Re: Tandem anchors for storm conditions
Yeah I’ll echo the others, if you want more insurance, go with a second big anchor and it’s own rode. I have had to bail out of a rough anchorage in the middle of the night, the potential hassle of tandem anchors has inspired me to never try it. If you are that concerned about the main anchor, then it’s not big enough.
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20-04-2018, 09:06
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#11
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Marine Service Provider
Join Date: Jul 2014
Posts: 6,103
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Re: Tandem anchors for storm conditions
Quote:
Originally Posted by Don C L
Yeah I’ll echo the others, if you want more insurance, go with a second big anchor and it’s own rode. I have had to bail out of a rough anchorage in the middle of the night, the potential hassle of tandem anchors has inspired me to never try it. If you are that concerned about the main anchor, then it’s not big enough.
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Well said.
_________
My preference would be to keep it simple. KISS Principle.
_____________
I will quote JIM CATE (as I greatly respect his and Ann's experience too).
JIM CATE wrote:
" The best dual anchor configuration is a better single anchor."
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20-04-2018, 09:23
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#12
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Registered User
Join Date: Sep 2011
Location: Good question
Boat: Rafiki 37
Posts: 14,145
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Re: Tandem anchors for storm conditions
Another “get a bigger (and/or better) bower” vote here. I think a tandem anchor setup is pretty much the same as the use of kellet. This has some utility in certain specific circumstances, but I don’t think it helps much with ultimate holding.
When you add in the complexity and risk of tandem anchors (and yes, I’ve tried it), the far better solution is a bigger/better bower, and perhaps a lot more rode.
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20-04-2018, 09:42
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#13
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Registered User
Join Date: Feb 2011
Location: Meandering about the Gulf of Alaska coast [NNE Pacific]— where the internet doesn't always shine... [Even Elon's...] Homeport: Wrangell Island
Boat: Nauticat 43 [S&S Staysail Ketch]
Posts: 1,671
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Re: Tandem anchors for storm conditions
Popeye,
We have tried it all over the years. [Kellets, dual anchors: inline, V, asymetrical, etc.] All approaches work to some extent.
We are firmly in the one large anchor camp, and haven't looked back. [45KG/99lb Spade- and 5 other anchors- on 43 ft 22 ton ketch.]
But that isn't what you asked about... If I had to use two anchors on a single rode, I would use an asymetrical approach as well documented by Drew in Practical Sailor.
We also always deploy a bridle on our all chain rode [and would on a rope rode too...] and if anticipating storm conditions, a back-up [lazy] bridle led to primary winches for adjusting. We also add a tertiary Hail-Mary single snubber to help avoid dealing with failures during the maelstrom.
Best wishes for success...
Cheers! Bill
__________________
SV Denali Rose
Learning every day- and sharing if I can.
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20-04-2018, 09:44
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#14
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Registered User
Join Date: Jan 2017
Location: Everywhere
Boat: Colegate 26
Posts: 1,153
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Re: Tandem anchors for storm conditions
Distant Shores has done some good videos about anchoring, both in unusual calm areas, and in dangerous places.
YouTube link to a search on their videos.
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20-04-2018, 10:29
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#15
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Registered User
Join Date: Nov 2016
Location: Gulf Coast of FL
Boat: Pearson
Posts: 408
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Re: Tandem anchors for storm conditions
I set two anchors in windy conditions or the possibility of. Main anchor first, then about 30-35 degrees the second usually 35-45’ to the side of the primary. I have ridden out four hurricanes with little problems or dragging.
__________________
Ken Z
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