How To Set Two Anchors
Two to Tandem: Rigging Dual Anchors to Maximize Belongings Ability
An outline of the theoretical & practical aspects of tandem anchoring
The concept of tandem anchoring is very popular amongst the boating customs. On cyberspace message boards, the topic seems to be raised virtually as often as discussions on anchors themselves. This article is intended to provide an overview of tandem anchoring and to address the more common queries.
Using multiple anchors on boats is fairly mutual, and various well recognized arrangements exist for handling particular situations. For example, a bow-and-stern arrangement may be used to concord a boat into a bang-up in order to minimize rolling, or a Bahamian Y moor may be used to deal with frequent 180 degree veers such as when anchored in a tidal expanse.
"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 weather condition – if it is not, then upgrade. [The tandem anchoring] functionality is provided for those more than 'extreme' adventurers who require it."
– Rocna Anchors User'south Guide
A tandem anchor gear up-up is intended to simply maximize holding ability. It does not deal with circuitous situations for which another rig may be more advisable, and works best at dealing with strong winds from a single direction. There is i point that should be strongly emphasized, and that is the fact that any multiple ballast rig introduces a complication to an anchoring set-up that is undesirable. Your master anchor should be sized to exist good enough on its own for most all situations – if it is non, reconsider your choice of that ballast. Tandem anchoring is for farthermost situations, in which a unmarried anchor large enough alone would not be practical for daily use.
Allow'south suspension to reiterate this. It is a mistake to think to tandem anchor regularly. You must have a primary ballast of a good size and blazon for your boat. If not, get one.
A Presupposition
Throughout this commodity, nosotros are assuming that a single anchor on its ain, for whatever reason, is inadequate. Clearly there is no point in using a tandem rig if a single pick will do the job. While this might seem obvious, information technology is important to point out, as information technology implies that a unmarried anchor of any multiple anchor rig volition drag if all the load on the gunkhole is applied to that 1 anchor. This is a situation which frequently needs to be considered.
Overview and Terminology
A tandem anchor rig is where two anchors are somehow connected in line with each other, on a unmarried rode which is deployed from the boat. "Rig" refers to the entire arrangement deployed in the water, i.e. anchors and rode, including shackles and/or swivels.
There is no standard for this, just for this article the terms will exist defined every bit follows. The primary ballast is the aft-most anchor, i.e. that closest to the gunkhole. The tandem anchor is the forrad most, i.east. that out in front end of the primary.
The rode is split into two sections, the primary rode and the tandem rode. The tandem rode is either attached to the forepart of the chief anchor or is simply an extension of the chief rode.
Figure one: Basic elements of a tandem ballast rig
The Alternative
A modified Bahamian moor, where 2 anchors are deployed from the gunkhole in the form of a V or Y shape and the boat can hang on both simultaneously, is ofttimes considered an alternative to a tandem rig. It has some advantage in that information technology can assist reduce swinging or "sailing" at ballast as the 2 anchors both exert some lateral restraint on the gunkhole.
Effigy 2: Modified Bahamian moor
However, in the interest of maximizing holding power, it offers a false security. It is almost impossible to get the load on the gunkhole distributed as on both anchors, fifty-fifty while the air current is in the verbal direction for which the anchors were fix. Rather, the stress tin oscillate from 1 anchor to the other, and if the stresses are enough to justify the utilise of dual anchors in the get-go place (otherwise why bother with the 2d at all?), the two anchors may simply exist "walked" downwind.
This set up-up is also completely incapable of dealing with veers in the current of air direction. If it survives such a veer at all, the two anchors will be out of rank, and the now windward ane will have to elevate back into line with its contrary number. At this indicate, the two anchors will be closer together than before, and such a process continued could run into the two anchors see and foul each other.
A further disadvantage is the requirement to utilise two identical anchors, or else have a total reduction of the capacity of the rig to the everyman common denominator. For instance, if one sets a Bahamian moor with a twenty kg anchor and a xxx kg anchor of the same type, the maximum capacity of the rig is defined by the point at which the 20 kg will elevate, whereupon the entire system fails and the extra size of the xxx kg anchor is wasted.
Theoretical Considerations
Once the determination has been made to use a tandem anchor rig, there are certain rights and wrongs. Unfortunately there exists little material on these issues, and much misinformation is distributed based on hearsay and poorly conceived notions. Grouped here are some basic rules, together with the theory on which they rely.
Never attach the rode of the tandem anchor to the front of the primary anchor…
…Unless the master ballast is designed for it, i.e. has a dedicated attachment betoken intended for a tandem anchor.
Effigy 3
Above: CQR, Bruce, and Delta crowns – these holes are not for tandem anchors!
Beneath: Defended tandem anchor attachment bespeak on a Rocna (lower hole)
Most anchors have a hole near their crown. All the same, this is not an attachment point for a tandem rode! Information technology is for a trip line. Never apply it for the tandem anchor, equally it volition unbalance the primary anchor when load is practical. It is also frequently not strong enough, intended only to take the weight of the anchor itself. From one cruiser: "I've torn the trip pigsty out of a 110 lb CQR. Mexican panga caught the float and pulled it at nigh 25 knots. No corrosion, but ripped the shackle right through the steel of the ballast."
Anchors which cannot take tandems attached directly to them include the CQR, Bruce, Delta, Spade, and Danforth types.
The only anchor which has a tandem attachment point, designed and tested specifically for this purpose, is the Rocna. This is considering the designer wished to be able to use a tandem fix-up when cruising in Patagonia and Antarctica, and made certain to include such functionality on his new development.
Defective such a defended attachment point, the tandem rode should be connected to the primary rode at the same place equally the primary. In do this ways that the tandem rode will probably really be the primary rode, with the principal attached a distance upwardly information technology. The disadvantage with this is that the rode leading from the chief to the tandem must laissez passer alongside the shank of the primary, which could interfere with it.
Figure 4 – Left: The importance of the attachment point. In this freeze-frame of a testing video, the tandem rode has been deliberately attached to the wrong place on the main, which has simply pulled out under load. Right: The same anchor in the same location, now with the tandem rode shackled to the right point
It is ideal to utilize anchors of identical types
This relates to the practical issue equally described below that it is difficult to fix both anchors later deployment. Unremarkably one must gear up the primary, and trust the tandem will set itself in one case the primary begins to drag. To have reliable knowledge that this will happen, what improve exam than an identical anchor having set only a few meters abroad?
The two anchors practise not accept to be of the same size, although a great disparity is undesirable.
"The tandem ballast technique is a very good technique with Fisherman anchors, and I personally did some experiments when the Glénans' boats merely had this blazon of anchor onboard.
"However, I began 1 day to have doubts when seeing tandem anchored boats dragging. I thus carried out a serial of measurements of holding with a powerboat. Most all the tests gave the aforementioned results: 1 required 200 RPM to drag two anchors in tandem (CQR or Fluke anchors), less than only 1 of these anchors alone. I investigated what had occurred with smaller anchors on the dry embankment of Pen Maryse in the Glénans, pulling by hand.
"Start problem with the CQR: it has no hole to attach the 2nd anchor (that should take been reason sufficient for not using this technique). I tested the shank, the trip line hole, and the elbow of the shank. On these three points, the effect is the same – the articulation has a bad effect; the plow cannot dig in. In that location remained the extremity of the shank, just information technology was not better. Almost each time, the chain came to obstruct the plow. The whole organisation depends solely on the about afar ballast. If this ane is smaller, it holds less than the large anchor alone. I noted as well that an anchor holds very badly in the furrow of another.
"With the 'fluke' anchors [Danforths]: again the same trouble of defended attachment, and at that place is nothing which can exist used except sometimes the trip line rings which are unremarkably not strong enough. However, from fourth dimension to fourth dimension I obtained results comparable with the property of just 1 ballast."
– Jean-Louis Goldschmid of the Nautical Heart of Glénans (translated from the original French)
Never use an anchor unreliable at setting as the tandem
In addition to using identical types, one should never utilize a type which is known to be unreliable at setting per se. Information technology is no good dragging your primary plow for x meters before getting a set, and hoping that the plough tandem volition perform similarly. The reality is it may drag 100 meters earlier setting, and that may be likewise far.
Most older "traditional" types are non terribly reliable at setting. Articulated plows such as the original CQR tin can crave multiple attempts to get them to bury. Fixed shank plows such as the Delta are meliorate. Claws like the original Bruce are ameliorate than the plow, but not necessarily in difficult sand, where they tin can lie on their back and neglect to right themselves.
Danforth types including the Fortress are shocking and are absolutely to be avoided. They are not full general purpose anchors, and take no identify in a tandem rig.
New generation anchors which have been demonstrated to set reliably are the best bets. These include the Spade, Bulwagga, and Rocna. Having said that, many new anchors promise everything yet deliver little, and then cheque carefully for credible examination results and other users' experiences.
Ever employ the larger anchor as the main
If there is a size deviation, use the larger anchor every bit that closest to the boat. The reason for this is that while the primary anchor must deal with simply its share of the horizontal pull, it is subjected to 100% of the vertical load (the load on the tandem is parallel to the seabed). The heavier anchor of the two will better handle this.
Ever employ concatenation for the tandem rode
While cipher is perfectly rigid in the scientific sense, equally much rigidity should exist between the ii anchors equally possible. This is and so when load is applied to the principal ballast, the tandem is immediately made to share its portion of the brunt, rather than allowing the primary to shift.
The best way to do this is to utilise only chain between the two anchors. Never utilise any course of rope. This also has the do good of ensuring the rode is resistant to any abrasion suffered from being on the seabed, which may comprise coral or stone.
There is no do good to be gained from the ambit of the chain's weight between the tandem and main. Accordingly, the chain tin be as light as possible, subject to strength requirements, which would make high tensile grades attractive options for this purpose. Yet, practical considerations such equally availability of existing lengths, and compatibility with windlass/capstan wildcats, will probably overshadow this signal.
Use an acceptable length of chain for the tandem rode
A rode the length of the boat is a adept rule of thumb. A few meters is not enough, as enough slack is required to let the primary to gear up earlier the tandem. As well, a greater length will improve permit the organization to bargain with a veer in the pull management. A sharp reversal may involve the master dragging back by the tandem, and the anchors should not be too shut together lest they foul each other.
Figure 5: Tandem and primary setting simultanously.
While possible, this is very difficult to do from a boat
Always prepare the primary anchor offset
This topic is expanded on below, but in that location is a theoretical element to information technology likewise. For an ballast to set properly, the pull on it needs to be linear and close to horizontal. The primary anchor volition not easily fix with the tandem already buried, regardless of how information technology is fastened to the rig.
If this rule is non followed, the tandem will apply a negative horizontal strength, which will crave greater overall loading in order to set the primary, which volition introduce a level of vertical strength which would not otherwise be necessary. This may preclude the primary setting at all.
It is theoretically possible to set both anchors simultaneously, but doing this in practice is all but incommunicable.
Accept that doubling holding ability volition require doubling telescopic
By no means must scope exist doubled, just information technology should certainly be maximized. In theory, if information technology is not doubled, it will not be possible to attain the full potential of the anchors.
For example, if one sets a 20 kg anchor on a scope of vii:i, this system volition offering a certain maximum capacity for holding. Add some other 20 kg anchor in tandem, and the holding capacity should double, right?
Figure 6: Illustration of the increased vertical pull on the primary. The situation is like fifty-fifty if the rode is attached to the master ballast's crown. The only solution is to deploy more telescopic to compensate.
Wrong. Equally mentioned in a higher place, the principal ballast has to handle 100% of the vertical load – it is not possible to distribute the vertical component of the load between the ii anchors, and, unless the anchors are assault a dry embankment horizontal with the boat, there will e'er exist such a vertical component.
The only style to deal completely with this actress load is to increment the scope. The maximum angle of pull on the primary ballast must be minimized. The more than scope, the better – although, in practice, whatever scope ratio past about viii:1 brings less and less benefit. Farther, do non imagine that heavy concatenation is a good thought; catenary in a tandem rig's rode will always exist negligible, as the rode will spend nigh of its time bar-tight regardless of the weight of the chain (assuming the tandem anchor is required in the first place). It is more important to ensure that the chain and rope in the primary rode is adequately specified and is strong enough. For more on ambit and scope, report the article "Ambit & Scope In Anchor Rode".
Don't bother with kellets (AKA anchor angels or buddies)
Kellets are supposed to increment the holding capacity of an anchor system by holding the rode low and hence keeping the angle of pull on the anchor closer to the ideal of parallel to the seabed. In practice, their issue even when deployed in an optimal point on rode (close to the anchor) is very minimal and the high loads which must exist expected on a tandem rig volition straighten the rode very quickly. They accept negligible effect on ultimate anchor performance in a regular anchoring prepare-up, and even less when tandems are deployed. For more than on kellets, study the commodity "Anchor Rode Kellets".
Figure seven: Simulation of a big kellet added to an all-chain rode. Fifty-fifty at this insufficiently depression tension, it makes virtually no difference to the angle of pull.
Source: "Mixed Rode Calculations" spreadsheet by Alain Fraysse
In the context of overall efficiency, the kellet is a bad investment also. The weight of the kellet used instead in the form of a larger ballast is a far more than sensible tactic. Figure 7 shows an anchoring system with 35m of 10mm chain, a 10 kg kellet at the square symbol, and a load of 500 daN (equivalent weight forcefulness of 510 kg) applied to the rode. An appropriate anchor for this organisation might counterbalance fifteen kg, and such an ballast on its own, let alone with a tandem, could be expected to agree far greater loads than in this example. Increasing the ballast's size to 25 kg and losing the kellet would maintain the same overall system weight, but massively increment the holding power.
Kellets are useful in other contexts, and have an application in containing swing radii in low-cal weather condition. However, in the context of a tandem ballast rig, they are pointless.
Your tandems may offer betting holding than a single anchor of the aforementioned full weight
This is no "do" or "don't", just rather an interesting point to add together to the theory. The belongings power of an anchor is determined by the volume of soil information technology displaces, and thus its mass. However this relationship is not quite exactly linear. Rather, when calculating the holding power of a larger anchor based on its weight and some performance factor, the equation for most ballast types raises the mass to the ability of something just over 0.9 (rather than ane). This ways that two anchors can in theory hold slightly more than one large 1 of the aforementioned summed weight, but the difference is small.
Reality bank check: this theory is not perfectly consequent with modest anchors, which are the involvement of nearly readers of this commodity. One counter-argument to this is the fact that seabeds are typically layered, and a larger anchor may be able to get its tip downward into a harder substrate than two smaller versions could, negating the theoretical benefits.
Figure eight: Drag furrows. Other anchors, dragged into these, tend to immediately coffin in the softer substrate.
A Misconception
A common piece of misleading advice is that tandem anchors are to be avoided because the tandem volition not concur well in the trough of the primary. The statement relies on the fact that the principal has plowed the seabed, and that this sand, mud, or clay will be loose and offering poor holding.
This is a logical fallacy. If both anchors have dragged far plenty that the tandem has entered the furrow of the primary, assuming an acceptable length of rode betwixt them as discussed above, then the rig has failed in any case and the point may be considered moot. An acceptable length of tandem rode will ensure that the tandem will always exist a safe distance away.
Furthermore, the assumption that the ploughed seabed offers reduced property is not necessarily true. In fact, in harder seabeds, it may offer better holding, as the ballast tin bury more deeply into it.
Practical Considerations
This section is shorter than "Theoretical Considerations", but only considering the theory applies direct to the practice and much applied material has been covered already. Here are listed some points which apply exclusively to the real world, which no computer or mathematical model can simulate.
Consider advisedly these issues. Deployment and retrieval are far more difficult with a tandem rig, particularly if the gunkhole, and its roller assembly and foredeck, is not designed for it.
Deployment
Presented hither is a recommended method for arranging and deploying a tandem rig. In that location are no hard and fast rules concerning this, and you may exercise what makes sense to you.
At that place are some requirements for the technique described hither, but such requisites should non be considered unreasonable if one seriously intends to make use of tandem anchors in the beginning place. Dual bow rollers is a necessity unless the tandem anchor is very light (information technology shouldn't be, as this would imply the primary anchor could be upgraded to an adequate size which would yet exist manageable). Cleats on the foredeck are besides required, port and starboard, plus preferably a windlass with both rope and chain gypsies.
Before deployment, install both anchors in their respective rollers. If they practice not fit alongside each other, the tandem (beginning to be deployed) could be hung just over its roller. The tandem rode should exist in place, either shackled to the appropriate attachment signal on the primary or being an extension of the main rode. This length of chain should be exterior the pulpit, ready to become overboard.
Figure ix: Proficient foredeck system. Note the twin rollers, port and starboard cleats, and horizontal windlass with rope and chain gypsies
A floating retrieval line is going to exist used betwixt the two anchors to facilitate deployment and particularly retrieval of the tandem. This line should be a few meters longer than the tandem rode, and if it floats there will be no possibility of information technology fouling the anchors (regular retrieval lines fastened to a beacon should not float, as their slack will collect on the surface and exist an obstacle for the boat's prop to foul).
Attach one end of this line to the rode attachment point of the tandem, and the other to that of the primary (or a bit farther upwards the chain, closer to the gunkhole – this is for ease of accessibility).
The tandem anchor itself is for the time beingness kept on the boat with its retrieval line, which is cleated on the foredeck. When ready to deploy, dump the tandem rode over the side. With the boat drifting aft slowly, let out the tandem until its chain rode takes up and it is hanging from the primary (in practice information technology will hit the lesser first unless y'all are in deep water). Abandon the retrieval line at this point.
Now launch the chief anchor. Brand sure the gunkhole has drifted dorsum far enough that it cannot land too close to the tandem, merely not so far that the tandem rode is nearly straight. A niggling space is required in which to gear up the primary. Finish the deployment past letting out as much scope every bit you can.
Setting the anchors
An aside: do not ready whatever anchor with reduced scope. It is common to do this, only to let out more scope once "finished". In practice, this may result in a poor set.
After deployment every bit in a higher place, back down and fix the primary in the normal mode. Do this hard and make certain it is set well. In harder bottoms, you will probably not be able to drag the primary in contrary, unless you accept a powerful engine. It is important to know the tandem will gear up itself when required, and the behavior of the principal at this point will ostend this.
In soft mud, you may exist able to drag the primary, in which case you should, until the tandem sets in turn. At this betoken your tandem rig is deployed.
Figure 10: Properly ready tandems. These two 10 kg Rocnas held more force than the test vehicle could exert, even using a 2:i purchase on the rode!
Current of air veers
In some conditions which you may wish a tandem rig to handle, such as hurricanes, veering winds are likely. Changes of direction of pull take the result of "raising the bar" for the considerations discussed so far, such every bit ensuring advisable types are used and with an acceptable tandem rode. A mistake or shortcut is more likely to be exacerbated and the consequences felt.
Assuming the presupposition in a higher place remains true (that a single anchor is inadequate), the principal anchor volition always need to be straight betwixt the tandem anchor and the gunkhole. This means that if the direction of pull alters, the primary must elevate into line. An anchor which is roll-stable, i.e. can elevate without popping out, and one which which will remain embedded whilst existence twisted around, is critical. Such types are not necessarily mutual, and most older types such as plows and claws suffer from a lack of these characteristics.
It should also be noted that while scope should exist calculated based on the primary anchor'south rode length, the boat's maximum swing circumvolve volition exist determined by the total rode length.
Retrieval
This is where the floating retrieval line will play its role. Pull upward the primary anchor until the retrieval line of the tandem is accessible. Bring this line to the other roller, and booty up the tandem. The maximum weight being pulled in this pace is that of the tandem plus half the length of the tandem rode – y'all may be able to practise this manually. If not, place the rope on the windlass.
One time the tandem is home, secure it on the roller past cleating the retrieval line. From this point on, the procedure is deployment in reverse.
Rode and equipment force
Tandem anchoring by definition places more than strain on everything. In theory the main rode may be dealing with twice the load which the primary anchor on its ain could handle. This means that all associated equipment needs to be carefully considered, including the rode itself. Is the safety working load of the concatenation still college than the strain expected?
Consider also shackles or swivels as these tend to be the weakest links. Concatenation stops on the foredeck are recommended, fifty-fifty if a bridle or rope snubber is to be used.
Use snubbers or other shock absorbing solutions as yous would normally. Consider also however that the forces on everything will be higher than normal, and that longer lengths of nylon may be a skillful idea. Abrasion protection should similarly be of an actress high standard.
Swivels
While swivels are often recommended, and would exist a practiced addition to other dual anchor rigs, they are unlikely to be useful with tandems. Swivels are useful for two reasons: they permit a boat to practise multiple 360s effectually its anchor without kinking or twisting the rode, and they facilitate retrieval if a section of the rode deployed is rope (as the anchor is not likely to come up the correct way to mate itself with the roller, every bit information technology would if the concatenation'south orientation on the gypsy is maintained).
The disadvantage is one of increased complexity and an boosted failure point, peculiarly if care is not taken to select a well built and solid design. Lateral loads are the most unsafe, and information technology is suggested that swivels are just ever installed "in line" with the rode, i.eastward. with a few links of chain between the anchor and the hinge and then that the practical strength can only ever be along its axis.
Since a tandem rig is not intended to handle multiple 360s in the first place, the swivel has little functional benefit. With regard to retrieval, it may be of some assistance for each anchor, although since retrieval is complicated and likely to involve more than work than normal in any case, it is hard to see any big reward.
Case Written report of a Failed Tandem Rig #1
Commensurate with the note at the starting time of this commodity, that tandem rigs are to be avoided unless absolutely necessary, is this instance study involving the United kingdom Marine Accident Investigation Branch (MAIB). The following is from the MAIB Safety Digest, March 2006:
A 10.7 thousand steel-hulled sailing yacht was beingness used for a 5-day training class on the westward coast of Scotland. Potent winds were being forecast for the coming night then it was decided to discover a sheltered anchorage.
A bay was chosen that the skipper had used several times before and the yacht was anchored in 2.vii 1000 charted depth. A 16 kg Delta ballast was prepared with chain and warp, and a seven.5 kg Bruce type ballast was fastened to the trip line eye of the Delta with four metres length and a trip line and float fastened. These were deployed as one unit, smaller outset. This is a technique known equally 'tandem' anchoring. In add-on, a 5 kg 'angel' [kellet] was rigged at twenty m length of chain, and nylon warp increased the overall scope to 36 m. The nature of the bottom was fine sand with some weed.
The anchors were set for a SW current of air and were tested with the engine running astern while transits were observed. Everything appeared to be secure and the GPS alarm was set to 0.03 mile (about 55 g). The barometer had been falling steadily all afternoon and, as the skipper and coiffure were turning in, was observed to exist falling more rapidly. At this point the wind was observed to exist SW strength 6.
Just before midnight the GPS alarm woke the skipper. He jumped out of his berth and saw that they were 0.04 mile out of position. He started the engine and donned a lifejacket, telling his coiffure of four to do likewise. By the time he was on deck, the depth sounder was showing minimal depth, and almost immediately the keel touched the bottom.
Attempts to motor off failed and the yacht soon listed by 20° to starboard, with the wind and sea on the port bow. A 'Pan Pan' was sent and best-selling by the local coastguard. The local lifeboat was dispatched to the scene but had some distance to travel.
It was before long established that the yacht was on a reef and was existence driven on by the weather. The bending of heel increased to 30°. The coiffure managed to recover the anchors during this time so that they could be deployed once more when necessary.
By the time the lifeboat arrived, the skipper had established that the tide was on the rise and that the depth would exist sufficient for them to float off. After more movement and pounding, they eventually came clear and were able to motor north to safely re-anchor. The yacht was lifted out to inspect for impairment, but was found to be unscathed.
Analysis
It is stated how the tandem (the Bruce) is fastened to the Delta (the primary). This method of attachment is likely the primary cause of the organization failing when the wind veered, assuming the Delta was always set properly in the get-go place.
In improver to this, find how the tandem rode was of but 4 meters length.
These ii fundamental flaws were exacerbated by other minor mistakes. Can yous identify them?
Case Written report of a Failed Tandem Rig #2
Alain Poiraud, French designer of the Spade anchor, dislikes the concept of tandem anchoring and relates his experiences as follows:
"Attaching two anchors to one rode, known as tandem anchoring, should be avoided.
"The double approach attaches a 2nd anchor with effectually 15′ of concatenation in front end of the first anchor. I personally near lost my boat trying out this idea. At the time, my first ballast dragged. Needless to say, it was an sometime generation model, so I decided to try something new. I added a smaller anchor in front end of the large ane. This worsened the holding ability as opposed to doubling it, drifting swiftly on the smaller anchor while the larger one couldn't grip at all.
"When an anchor has dragged, a trench formed behind it and this speedily backfilled with loose un-compacted sand. These areas can be nonetheless visible after several tides and may explicate why some pop anchorages are criss-crossed with patches of poor holding. And then, if the virtually proximal ballast prepare, they are very good chances that the [far] anchor will fall down in this loose lesser, with, equally a consequence, a poor belongings!
"I have done a series of approximately 70 tandem anchorages in the clear waters of the Med, diving on virtually all of them. In 62% of the cases, but ane ballast was prepare. During bad atmospheric condition, you lot will not have the possibility to dive to check your anchors, and you lot only have to 'trust' your anchors, which is what I call 'the Russian Roulette' anchoring.
"At showtime, I tried to attach the smallest flat anchor (a 16 kg Brittany) with v meters of chain to the hole at the back of the shank of the CQR (20 kg), and I noticed that it will more or less modify the equilibrium of the CQR.
"So I move the five meters chain and attach information technology at the shackle of the CQR (the extremity of the main chain) but I didn't notice any divergence."
Assay
Poiraud'due south commentary seems to indicate he routinely uses "around 15 feet" of chain for the tandem rode. While his set up-up is never described in great detail, what other possible flaws tin can you detect in his method of tandem deployment?
Conclusion
Before attempting to apply a tandem anchor rig, it is critical to empathize the theory. The bar is raised very high, higher probably than well-nigh sailors accept the experience for. By the fourth dimension a error is realized, information technology is oft too tardily, the weather condition non permitting any correcting action. Examples of scenarios that can arise from misunderstandings are presented above in the instance studies.
In add-on to studying the theory and properly planning your rig, it is suggested that yous do deployment, setting, and retrieval in manageable conditions before having to depend upon it for existent.
References
- "Boosted Notes On Cruising In S Republic of chile" Andy O'Grady and Ian & Maggie Staples (Royal Cruising Club Pilotage Foundation), Chile: Arica Desert to Tierra Del Fuego 2004
- "Tuning an Anchor Rode" Alain Fraysse, alain.fraysse.gratuitous.fr
- "Avis au sujet des « ancres duelles »" Jean-Louis Goldschmid, Nautical Heart of Glénans, June 2007
- Rocna Anchors Tandem Testing, Rocna Anchors, July 2006
- "Case Study 22" Marine Accident Investigation Co-operative, MAIB Safety Digest March 2006
Source: https://www.petersmith.net.nz/boat-anchors/tandem-anchoring.php
0 Response to "How To Set Two Anchors"
Post a Comment