Anchor rode bridle connection

[willbank]

So, I have a 3250kg boat on an Ultra anchor, 5m of stainless 6mm chain and 50m of 12mm rode. I want to attach my mooring bridle for over-night anchoring and am wondering:

1) use an Alpine Butterfly Loop in the rode and then shackle the bridle

2) use a spliced 5mm dyneema loop of 30mm to make a Prusik or Klemheist and shackle to that.

Advantages of (2) being it may be stronger and also, in extremis, would not add a knot to the rode which might be tricky to undo or foul the windlass on recovery.

Any advice?

 

[lw395]

Why do you need a mooring bridle on a rope rode?
Just cleat the rope, job done.

 

[greeny]

Maybe a cat?

Why do you need a mooring bridle on a rope rode?
Just cleat the rope, job done.

 

[willbank]

Why do you need a mooring bridle on a rope rode?
Just cleat the rope, job done.

Good point! Was intending to split the load over 2 cleats but that may be redundant.

 

[Neeves]

A bridle s not entirely a daft idea - it will steady the yacht a bit at anchor (in the same way a bridle steadies a catamaran). Don't give up on the idea. Other monohulls (not many I admit) used a bridle

Jonathan

 

[Catalina36]

Rolling hitch.

 

[BabaYaga]

A bridle s not entirely a daft idea - it will steady the yacht a bit at anchor (in the same way a bridle steadies a catamaran). Don't give up on the idea. Other monohulls (not many I admit) used a bridle

Jonathan

I cannot see how a bridle could be useful on a monohull.
The only time when cleats both sides will be equally loaded would be when the bow is exactly strait into the wind. But since practically all yachts sail a bit (or quite a lot) at anchor, the load will always be on the leeward cleat, would it not?

 

[LadyInBed]

1) use an Alpine Butterfly Loop in the rode

They are buggers to undo after they have been put under tension!
A figure of 8 loop might be easier to untie, but I can't really see the need for it on rope rode in normal conditions on a monohull.

 

[zoidberg]

2) use a spliced 5mm dyneema loop of 30mm to make a Prusik or Klemheist and shackle to that.

Neeves - and I - would suggest you consider a STRETCHY bridle-snubber, using a 10m. or so length of nylon or redundant climbing rope.
Why? In choppy conditions, the STRETCH absorbs most of the recurring shock loads as the bows jerk upwards, which translates into fewer jerks on your anchor, so it is more likely to remain hooked into the seabed.

That's easy to rig, adjust, and de-rig.

 

[Neeves]

With thanks to Zoidberg.

Catamaran, multihulls all use bridles for a reason - that works. Its more difficult on a monohull because the bridle will be narrow (or not as wide as on a multi) so the effects will be less - but there will still be a positive steadying effect.

But you do need to rig a bridle - not a single snubber with the rode going to the opposing cleat.

The rope rode will stretch differently to the snubber and the rode, as it incorporates some chain, will 'stretch' due to the cateneray altering with wind. You thus need to rig a balanced bridle, both arms the same type of rope, as Zoidberg states - climbing rope, and arranged so that you maximise the angle. To get 'length' - commence the bridle at the transom and run to a point where you can take the bridle outboard, trying to maximise the angle where it joins the rode and minimising chafe.

You want to be introducing as much elasticity as you can and 'thin' climbing rope 8mm is better for a small yacht than 12mm (the latter is suitable for a larger yacht (say 40'/45'). If you check and interpret you will find that climbing rope does not have the strength of your rode but it has much greater elesticity, you are sacrificing strength for stretch. But your fall back is still and always should be the rode, which should be secured, in the OPs case to a strong point, if it were all chain to a chain lock (we use a hook on a dyneema strop to a strong point). bridles and snubbers will not last for ever - so make sure you always use a fall back. If you cannot source cheap 8mm climbing rope then a 8mm 3 ply or braided nylon will suffice. We route our bridle arms through the stanchion bases, its unobtrusive, and we leave it permenanlty in place - we just attach bridle to the rode.

If your yacht yaws - check the reasons for yawing of yachts and minimise the causes (get the dinghy off the foredeck etc).

Each yacht will have different fairleads, a different arrangement for securement at the transom, different ways to maximise the bridle angle - there is no 'one size fits all'. If you anchor a lot - play around with arrangements until you find one that suits and is convenient.

One other advantage to a bridle, you can alter the angle at which the yacht lies to the wind to allow you to lie better to a swell or chop - making the yacht more comfortable.

Baba - you are correct - the bridle does not split the load evenly, it moves from one arm to the other. As the yacht passes through the eye of the wind the load will be split - but that is transitory.

The other way to reduce yawing is to anchor in a 'V' but for one night that can be a bit of a faff - better to choose a more secure anchorage in the first place. Again the two anchors do not share the load but each anchor, or the rode for each anchor, is alternately tension - but that tension is in the 'set' direction which ensures each anchor is tensioned in a direction offering its maximum hold.

As Zoidberg points out - every movement of the yacht is transmitted down the rode (perfectly for an all chain rode with no snubber) to the anchor - and an anchor will not appreciate constant tugging in a variety of random directions, up and down, side to side - snubbers, bridle and a rope rode offer a means to manage the resultant twitching of the anchor. If you do not believe this - dive on your anchor when all your chain is off the seabed and touch your anchor - it twitches all the time. Twitching reduces the shear strength of the seabed in proximity to your anchor - good anchors might dive more deeply, others might simply make a bid for freedom.


There are owners of monohulls on YBW who use bridles - they are not 'so' unusual.

Jonathan

 

[thinwater]

If you have a rope rode (the OP does) then the bridle should be non-stretch. Yes, this is the opposite of chain, and for logical reasons:

• You don't need shock absorption. The bridle would only represent a rounding error. In fact, a rode can stretch too much, increasing horsing at anchor (in the US at least, that means fore-aft motion).
• A non-stretch bridle will chafe less because there is no movement or sawing against the chock. In fact, chafe can be the best reason to use a bridle with a rope rode.
• Stability. A nylon bridle will distort when the boat yaws to one side, as the legs stretch, changing from an isosceles triangle into a leaning, irregular triangle.

I use a Dyneema bridle on my trimaran with rope rode. I used a Nylon bridle on my catamaran with chain rode. Different cases.

 

[Neeves]

We use a 12mm bridle, 30m each arm, on a 7t 38' LOA 22'6" beam, catamaran - and think the 12mm too much. I'm toying with down size to 10mm. We use lightweight chain, 6mm. We don't have 'too much' elasticity. The OP has a 3.25t yacht and rope12mm rode and I doubt it stretches much at all - but he needs the 12mm for strength (not elasticity).

He has no catenary - the chain is too short. I think he can accept more elasticity.

The bridle will distort and if long enough, helps to re- centre the yacht - as the distorted triangle 'side' returns to its undistorted length.

I don't have the maths - just usage.

Mixed rodes have been used for decades and horsing, backward and forward motion (or yo-yoing) has never been mentioned as an issue (no matter what length of rope) - possibly because the rope rode is chosen for strength, not elasticity.

Chafe is a different issue - and minimising chafe should be a focus. Chafe should restricted to the means/location by which the bridle arms (or a single snubber, or a rope rode) are taken outboard - and there are many ways to manage this, sleeves being but one example.

With such a short length of chain the big issue is 'wandering around' in light fluky winds - and then he needs a decent anchor (and Ultra fits the bill perfectly) and short rode (and/or a hammerlock)

Jonathan

 

[Neeves]

My view on 'having too much elasticity' is that there may be truth in it if your rode, snubber or bridle is too thin and you work it well beyond its WLL. This may lead to the comments of yachts horsing moving back and forth, or as I might call it yo-yoing.

I have seen it mentioned fairly regularly on internet forum but when I question those who do use long snubbers (as snubbers, so they are genuinely elastic) they have no knowledge of it themselves. If you speak to people who use a nylon rode (and our spare rode is 15m of 6mm chain and 40m of 12mm 3 ply) no-one admits to it being an issue - logical though it may sound. We have no experience of it - and we do, did, use our spare rode (occasionally) when we lost our anchor and complete chain rode (retrieved) and when the solenoid on the previous windlass locked (a number of times) and when we anchor in a 'V' - but the latter is not the same scenario.

To me its one of those truths that isn't. Like dyneema is very susceptible to UV, commonly spouted in the 80s and 90s - until someone actually tested it or, big anchors are safe at short scope (for which no data has ever been produced). These truths are made more true by their repetition. When we bought our dyneema for our X99 we were warned by Bridon not to strip the outer cover off, unless we were restricting the cover removal to the rope 'inside' the mast or boom and that this was how Rothmans had done it. How times change....

Now - if someone has experience of horsing or yo-yoing - I, for one, would like to hear the detail - and show that I am wrong and need to get out more.

Jonathan

 

[thinwater]

Based on my testing and experience with nylon I don't see why he would need more catenary. I used less chain than that for many years. It does increase the scope requirement, but that also depends on his local waters. I don't know. Chain would reduce yawing under light to moderate conditions.

Yes, 12 mm is plenty fat. No, he probably does not have too much stretch. But it can happen. I tested the yawing angles and rode tension on my boat (F-24) with 8mm climbing rope, and 3/8" and 1/2" 3-strand nylon. The loads and the yaw angle were lower with 1/2-inch nylon. This was with 100 feet of rode out, only 10 feet of which were chain. The difference was small but measurable. I doubt you would notice it if you were not specifically looking for it. It would not be there on most days, only under specific weather conditions. Only with some boats; my PDQ would show loawer loads the more I increased stretch, without apparent limit, in part because the boat did not yaw. The reason is that 100 feet of 1/2" is small enough to absorb all wave impacts, so additional stretch only increases movement, and at this point rode tension is increased more by yawing than it is reduced by more stretch. Not an internet truth, more like a rare truth, because it only happens when thin rode, the right very gusty winds (it is stretch from medium duration wind gusts that causes it, not waves), and a lively boat all combine. It is more likely if the boat has little or no keel, such as a power boat or a boat with the boards up. Yeah, it's rare.

In fact, polyester rode, woven for increased elasticity (single braid), is quite popular in the UK and Europe. They like the improved chafe resistance and feel that nylon is too stretchy. I don't agree with much of this, but you can make a case for limiting stretch. I've tried polyester a few times and the loads were much higher. I never tried in on the F-24. I should and I will. https://www.petersmith.net.nz/boat-anchors/docs/dashew-right-rode.pdf

You are incorrect about bridle distortion geometry. It has the effect of moving the triangle base to windward, which will be too narrow on a mono already. In all likelihood, however, it won't matter on a mono, because once you have single leg loading this geometry factor vanishes. It is more relevant the wider the bridle is, and my boat is a trimaran. In fact, a bridle will probably have little effect on a mono's yawing because it is so narrow. My only reason would be chafe, depending on the set-up. The other advantage of a Dyneema bridle, for me, is that you don't have to store it away; it is thin and the sun won't bother it much. Crawling out on the floats of a tri in chop is not that much fun.

 

[lw395]

AIUi, in the old days, they used a system a bit like a 'bridle' but deliberately pulled the anchor rode across to one side. Known as an anchor spring. The idea was to get better aim for the cannons...

 

[willbank]

Thanks for all the comments - interesting discussion. Just to throw this in here: I also have an 8kg ring or kellet for mooring in tight bays where you want to limit movement but maintain decent scope. Not used often but nice to have for some occasions. Def increases elasticity.

 

[thinwater]

AIUi, in the old days, they used a system a bit like a 'bridle' but deliberately pulled the anchor rode across to one side. Known as an anchor spring. The idea was to get better aim for the cannons...

Still useful, when someone anchors too damn close. A shot over the bow is certain to be more effective than a scowl.

 

[noelex]

Most boats that use an all chain rode have too little stretch in their snubber. However, it is possible to have too much stretch so some experimentation in the length and diameter of snubber is needed. In strong conditions a length of round 10-15m of appropriately sized nylon is a good starting point.

Bridles help by providing a force that helps straighten the yacht as it yaws, but on a monohull the limited separation of two legs of the bridle mean the effect is only slight. The drawback of the bridle on a monohull is that the force is moved backwards towards the centre of lateral resistance and this tends to increase the yawing. Once again, some experimentation is needed, sometimes the bridle is detrimental and often the difference between with and without a bridle is so small the prefered option (a single line over the bowsprit, or a bridle) depends on which option is more practical to rig.

Bridles provide two attachment points, so there is some redundancy which is nice, but in very adverse conditions it is worth considering rigging two completely independent seperate snubbers. This is usually simpler without a bridal, but this depends on the boat.

 

[zoidberg]

I'm revisiting the OP's question - and the answer is 'Yes'.

Beyond that, there's much wisdom.

Should yawing about in certain breeze conditions be a nuisance - and a Contessa 32 may very well be susceptible - then one simple and effective answer is a small riding sail hoisted up the backstay. There are simple designs on the 'web, and one may be made up in a couple of hours from a knackered dinghy sail.

 

[Neeves]

I agree with Zoidberg - it is better to define why your yacht yaws and take whatever measures are possible to reduce the behaviour and a riding sail is a well know and accepted technique. Historically they appeared to be more common than today - but maybe my memory is failing

Yawing can be caused by wind shear (as you see at airports in strong wind and aircraft are weaving as they come into land - gusts of wind from unpredictable directions. Common in tight anchorages with gaps in trees and valleys directing wind such that the yacht behaves like a demented cow.

Other than a riding sail (there are other methods) the common solution is chain - but we all carry finite amounts of chain and the weight of the link is fixed. You can deploy more chain, but not in a tight anchorage nor if the anchorage is crowded. Once experienced you can go home and buy more chain, bigger chain and more of bigger chain - but many yachts do not enjoy weight, or more weight in the bow - and weight in the bow does not help sailing ability - unless you own a traditional heavily (well) built yacht. Today's yachts tend to be flighty. 'Changing' chain is also expensive.

A snubber or bridle is one way (and it is the same way that a chain acts) to tame yawing (and seasawing due to chop).

Now the idea that you can have too long a snubber (because it introduces a yo-yowing effect) lacks sufficient statistical background. One reason to use a long snubber is that the energy developed by the yacht, whether through seesawing or veering, is managed by 2 times the length (say 20m) of rope rather than the suggested, say 10m. The snubber consequently will have a longer life. It is easier to add a long snubber than necessarily be able to deploy more chain (no more chain, no room) - you can double snubber length (if you have the rope) by using a purchase system down the deck and not increase rode length beyond the bow (you will need to increase the length of the lazy loop).

There are many ways to skin a cat and suggesting there is a maximum snubber length - without have tried a longer one - lacks any sense (but its common to make sweeping statement without background on the internet).

The common catamaran snubber are 2 snubbers which may be two independent ropes or one continuous system. Usually they are too beefy - and lack elasticity - but the 'V' does tame yawing. Our system now introduces a vertical 'V' but retains the conventional horizontal 'V' and we control both yawing and seesawing with one device. A further benefit of our arrangement is that the bridle hook is always below sea level which improves, significantly, the scope ratio (allowing the rode to be closer to the horizontal -if this is a focus for you). No longer do we need to add the height of the bow roller above sea level - just work on depth of water. A number of monohulls do use a bridle (maybe they will add their experiences as some are members here) and the idea they offer no benefit is contradicted by those that use them. (I cannot comment but take their experience at face value - if you don't try it you will not know). Similarly if you don't try a long snubber, bridle - ours is 30m, you simply will not know - and you are guessing (and your statements lack any credibility).

It merits comment - if you are in deep enough water then when the gust comes all your chain is off the seabed and looks 'straight' when the gust eases your chain adopts its 'catenary sag' , another gust comes through etc etc - no-one complains about yoyowing - yet the yacht is continuosly moving back and forth (in similar way it does with a snubber) as the catenary straightens and sags. With 30m x 12mm of an elastic bridle (which are two snubbers joined at a common chain 'hook', the movement on our cat is much more comfortable than with 15m and factorially better than a short inelastic bridle. We are thinking of downsize to 10mm, same length, as the benefits of 30m x 12mm are so stunning - but we have just bought the 2 x 30m lengths and there is a financial constraint just to prove a point (when the 12mm ropes work) For a smaller yacht you would not need 30m, maybe 2-3 times yacht length, and smaller rope, say 8mm.

There is a detailed article on our system, but behind a paywall, (the May 2020 issue of Practical Sailor), if anyone wants more detail - send me a message.

Jonathan