Yawing at anchor

[Neeves]

Most of us when we buy a yacht buy an AWB, or in the context of the thread a plastic fantastic. These yachts come from Benny, Jenny and Bav and in general are pretty lightweight. They have interiors that would put an inner city apartment to shame (which is one reason people buy them). There is a decreasing number of well presented old designs which are heavier have long keels, sometimes full length and have, dream of dreams, solid wood furniture with dovetail joints. The older yachts have a much more solid layup (might even be timber) and the new yachts will have much foam and thinner layup. The newer yacht might have a bulb on the keel - much less likely on the older yacht.

I wonder if those that have had both and have spent some time on both at anchor whether these different yachts yaw differently. I'm not specifically referring to a natural propensity to yaw, as a result of 2 headsails on furlers or keeping the dinghy on the bow - but that might be part of the background - but if you are in an anchorage where winds gust from different directions does the AWB yaw (and faster) more than the older yacht.

I'm think of the occasions where a gust comes from the side and both yachts, will move with this new side gust, does the heavier one move sedately and the new one take off like a scalded cat - and at the end of the yaw does the slow yaw but heavy yacht appear less 'snatchy' than the flighty lightweight wonder.

Yawing and snatching at anchor is, one reason, anchors drag but basically does the lightweight vessel yaw more than the older heavier one and does the lightweight one yaw at a greater speed. The snatch is the combination of weight and speed, do the higher weight of the old yacht balance off with slower speed and the fast speed of the flighty yacht balance the lighter yacht - and the final snatch is 'similar' for similar sized yachts.

I've not anchored in a traditional long keeled yacht. My background is all lightweight yachts (though today my idea of a lightweight yacht is a bit dated .

To me logic suggests the older yacht will be more comfortable - is this correct - or just a romantic dream.

If the older yacht is more comfortable (in anchorages with williwaws) then snubbers will tend to have a more limited market for that sector and anchoring experiences should be 'better'

I'm looking to be educated - I might be able to better explain, or qualify what my 'question' is - but basically I don't know nor have an opinion.

Jonathan

 

[prv]

We had a 24’ long-keeled gaff yawl, followed by a relatively light 34’ fin-keeled sloop. The yawl was certainly better-behaved at anchor - though part of that might also have been the all-chain cable (that boat needed weight in the bow to correct the trim) versus the mostly rope rode in the larger boat (fine bow and the reverse problem).

Pete

 

[thinwater]

Define "snatch." Actual slack in the rode? A quick turn at the end of the swing? Tension X% above the base (no yawing) load?

Since I do not believe actual slack exists (if it does, post a picture--I've never seen actual slack on any boat I have watched yawing--the rodes remains relatively snug, too much so to hold in your hand, for example, though the tension certainly varies), then we need to determine and then define what we are talking about.

If there is no actual slack then there can be no "snatch" in the common meaning of the word, since the bow of the boat is describing a semi-circle that reverses. The dictionary says "abrupt," but what does that mean in this context? The catenary coming out of the chain can feel pretty abrupt, but that would only happen in relatively light winds. There is certainly no slack as the boat moves across the swing. There can be noise, as the chain snaps from one side of the roller to the other.

Definition of snatch

intransitive verb: to attempt to seize something suddenly


transitive verb: to take or grasp abruptly or hastily. Snatch up a pen. Snatched the first opportunity. Also to seize or take suddenly without permission, ceremony, or right. Snatched a kiss

 

[Neeves]

My experience differs

I anchored and measured tension in the rode at different scopes. I measured peak loads as a Seabreeze developed - this way I could start of with low loads and low windspeed and the tensions increased as the Seabreeze developed from very light winds to a maximum gust of 35 knots.

I also measure the variation of wind and yacht direction.

At times the yacht (catamaran) would be at 90 degrees to the wind.

I was anchored where these was little chop, no swell, but subject to a gusting wind which would be gusting either side of e hill directly ahead, so the wind would be coming from one, or both sides, alternately.

The rode must have been slack as the yacht would 'sail' at anchor and the maximum loads were snatches - as the yacht 'hit' the end of its tether.

There was no snubber being used - but a Dyneema bridle - I was looking for worst case, maximum tensions.

A snatch is a sharp, sudden and catastrophic increase in tension from 'nothing' to 650kg - like motoring into a brick wall.

I have had the same 'hitting a brick wall' in tight anchorages and deployed shore lines to restrict the movement. In the worst case - and this was before I learnt about the evils of swivels and developed my Boomerang - The snatches were such I bent a swivel. What was interesting (or not). Our cat was swinging, yawing, caused by willwaws and was sailing at anchor - the snatches were sufficient to bend a swivel - but when we were rigging the shore line it required little strength to hold the the shore line. So the wind gust applied to the cat could be held but once the cat started to move it developed sufficient energy to bent the swivel.

In terms of THE definition, not like snatching a kiss . More like stealing a necklace and discovering the chain we too strong? or a dog chasing a rabbit but restrained in full flight by its leash.

This means the rode is slack until you reach its maximum length. The rode is not allowing the yacht to travel in a semi-circle, its moving freely until restrained. Hence the use of the word 'Snatch' - the yacht is 'snatching' at the anchor.

Jonathan

I would post a picture - but it is not something you think about at the time . Again in watching other yachts - they are 'sailing' not tethered. They are not swinging - like a horizontal pendulum and describing the arc of a circle (which I only see in very benign conditions) - but 'freely' sailing.

 

[Daydream believer]

Both my long keel Stellas were kept on a mooring. The first for 10 years at Burnham on Crouch & was anchored on a trot very close to others. It sat there very nicely. Although it would have clashed it it had come out of alignment with the others, it never did. The second in open water , sat nicely. When I bought my Hanse 311 I had to keep it on my open water Stella mooring for 3 months whilst I waited for a berth to become vacant at Bradwell.
During that time, I would walk down to the shore during rough weather & watch my Hanse complete full 360 degree pirouettes on the mooring.

 

[Supertramp]

Most of us when we buy a yacht buy an AWB, or in the context of the thread a plastic fantastic. These yachts come from Benny, Jenny and Bav and in general are pretty lightweight. They have interiors that would put an inner city apartment to shame (which is one reason people buy them). There is a decreasing number of well presented old designs which are heavier have long keels, sometimes full length and have, dream of dreams, solid wood furniture with dovetail joints. The older yachts have a much more solid layup (might even be timber) and the new yachts will have much foam and thinner layup. The newer yacht might have a bulb on the keel - much less likely on the older yacht.

I wonder if those that have had both and have spent some time on both at anchor whether these different yachts yaw differently. I'm not specifically referring to a natural propensity to yaw, as a result of 2 headsails on furlers or keeping the dinghy on the bow - but that might be part of the background - but if you are in an anchorage where winds gust from different directions does the AWB yaw (and faster) more than the older yacht.

I'm think of the occasions where a gust comes from the side and both yachts, will move with this new side gust, does the heavier one move sedately and the new one take off like a scalded cat - and at the end of the yaw does the slow yaw but heavy yacht appear less 'snatchy' than the flighty lightweight wonder.

Yawing and snatching at anchor is, one reason, anchors drag but basically does the lightweight vessel yaw more than the older heavier one and does the lightweight one yaw at a greater speed. The snatch is the combination of weight and speed, do the higher weight of the old yacht balance off with slower speed and the fast speed of the flighty yacht balance the lighter yacht - and the final snatch is 'similar' for similar sized yachts.

I've not anchored in a traditional long keeled yacht. My background is all lightweight yachts (though today my idea of a lightweight yacht is a bit dated .

To me logic suggests the older yacht will be more comfortable - is this correct - or just a romantic dream.

If the older yacht is more comfortable (in anchorages with williwaws) then snubbers will tend to have a more limited market for that sector and anchoring experiences should be 'better'

I'm looking to be educated - I might be able to better explain, or qualify what my 'question' is - but basically I don't know nor have an opinion.

Jonathan

I have a 36ft, long keel, 10 tonnes displacement ketch with the main mast mounted several feet further forward than comparable sloops and ketches. Plus it has a large pilothouse. My experience is limited in terms of number and severity of anchoring experience with it.

However experience so far with chain/rope or all chain rodes is that there is less yawning or sailing at anchor even when tide rode than any bilge or fin boat I have sailed. There was a previous post about using backstay mounted scoops or sails at anchor and having the mizzen up helps by reducing swinging further. I also use a V bridle with the chain giving 2-3m of rope attached to cleats each side of the bow which also helps. But I don't know yet what full gale conditions would show.

My instinct so far is less sailing around on the anchor with weight and long keel but this might be offset in a rough or rolly anchorage by higher pitching and wave induced forces. I suspect the shearing around will still happen but at a much higher wind strength than for lighter fin keel boats. A side benefit is much less shearing when dropping and raising the anchor especially when the mizzen is up and sheeted dead centre.

I hesitate to contribute to more anchor threads but for those of us who routinely cruise using anchors rather than marinas understanding the problems and options when choosing anchorage location and deploying anchor, rode, bridle, steadying sails etc is useful. The whole point is to learn with the experience and knowledge of others. Life is too short to be expert at everything.

 

[KeelsonGraham]

Chartered a Jenny 36 in Croatia and was moored to a swinging buoy during 60kt winds. She yawed and rolled all over the place, through about 30-40 degrees either side of the wind.

The tender with outboard attached was flying horizontal from the transom. So maybe this isn’t a completely typical example of yawing.

 

[Neeves]

I hesitate to contribute to more anchor threads but for those of us who routinely cruise using anchors rather than marinas understanding the problems and options when choosing anchorage location and deploying anchor, rode, bridle, steadying sails etc is useful. The whole point is to learn with the experience and knowledge of others. Life is too short to be expert at everything.

Don't hesitate - if you are out there doing it - you have real experience, share it. I don't have and cannot aspire to (and most do not have) your experience.

Thank you for posting, thank you for mentioning your hesitation.

Jonathan

 

[Stemar]

We spent far more nights at anchor in Jissel (24ft Snapdragon with bilge keels) than we did in marinas, and we'd swing a bit, but she was generally pretty well behaved. Little or no snatching, though whether that was because we had a mixed rode and put plenty of octoplait out in any breeze.

We haven't anchored with Jazzcat (8m X 4.5m Catalac) yet, but with a polysteel bridle, she's very well behaved on her mooring compared with the monohulls around us, swinging a lot less than them, and no snatching. The other advantage of a rope bridle compared with chain is the lack of graunching of chain in bow roller.

 

[JumbleDuck]

Mine (long keeler, high bow) is rock steady up to F3, sails to and fro like nobody's business in F4 and is rock steady again by the top of F5. That's at anchor. On a mooring she's steady all the time.

 

[BobnLesley]

I've no science that I can offer you, only opinion based on observation during 10+ years full time aboard, with 95% of that anchored on a 35' heavy displacement long keeler: We reckoned that the more modern/lighter designs 'danced' around there anchors far more than we did and moved around/changed direction far more quickly than we did, we also held that their generally being held on 8mm chain rather than the 10mm we used added to those difference. That difference in motion increased with the wind strength, so if the wind was forecast to get lively we would be more concerned about an AWB being anchored close to us than another long keeler.

 

[dunedin]

No.

 

[RichardS]

A riding sail is the answer.

Richard

 

[Daydream believer]

A riding sail is the answer.
Richard

With wind over tide??

 

[Neeves]

There are lots of answers - bridle, elasticity, more/heavier chain, riding sails (stay at home) reduce windage on the bow.

But if the yawing is due to williwaws then a riding sail may (any feedback?) exacerbates the answer.

I don't for the life of me think there is one answer but as Thinwater asked 'what are we talking about'. I don't want to restrict the answer - I'm interested in what actually happens - I'm here to learn. Maybe later we can each take lessons from what other people relate.

In the interim - thank you for the first hand experiences - and please, please do not feel because there is an anchor involved (if you were not at anchor then the question does not arise ) you should feel potential for threats.

Take care, stay safe

Jonathan

 

[JumbleDuck]

Very occasionally, my boat lies at anchor the wrong way round, so the chain goes over the bow roller and heads back under the boat to the anchor somewhere astern. She's perfectly stable and comfortable like that, but I have never been able to work out what combination of wind and tide does it. It seems odd whatever force is strong enough to move her in one direction isn't strong enough to swing her round as well.

 

[Neeves]

I've no science that I can offer you, only opinion based on observation during 10+ years full time aboard, with 95% of that anchored on a 35' heavy displacement long keeler: We reckoned that the more modern/lighter designs 'danced' around there anchors far more than we did and moved around/changed direction far more quickly than we did, we also held that their generally being held on 8mm chain rather than the 10mm we used added to those difference. That difference in motion increased with the wind strength, so if the wind was forecast to get lively we would be more concerned about an AWB being anchored close to us than another long keeler.

I'd have said the same (and still do). But that does not mean our observation are typical - hence the thread.

Jonathan

 

[prv]

Very occasionally, my boat lies at anchor the wrong way round, so the chain goes over the bow roller and heads back under the boat to the anchor somewhere astern. She's perfectly stable and comfortable like that, but I have never been able to work out what combination of wind and tide does it. It seems odd whatever force is strong enough to move her in one direction isn't strong enough to swing her round as well.

Mine does that regularly in a certain spot that I like to anchor. It's a concern because with rope rather than chain it can easily result in getting the warp wrapped around the keel. As well as the possible risk of cutting it (the aft edge of the keel is quite sharp) that also puts us beam-on to the current with corresponding massive increase in load on the anchor.

Pete

 

[JumbleDuck]

Mine does that regularly in a certain spot that I like to anchor. It's a concern because with rope rather than chain it can easily result in getting the warp wrapped around the keel. As well as the possible risk of cutting it (the aft edge of the keel is quite sharp) that also puts us beam-on to the current with corresponding massive increase in load on the anchor.

I'm glad to hear I'm not alone. Have you any idea why it happens?

 

[prv]

Not really. It seems to be when the wind and the tide are about balanced in their effect on the boat. The tide controls the boat's direction - she faces up into it, and the rudder will steer her side to side - but the wind from astern seems to push her forwards over the tide and past the anchor. Sometimes the warp points right off to port or starboard, but more usually it will be running tight down the side of the hull. Whether it eventually ends up coming free or wrapping round the keel depends which way we roll out of that situation when the forces change.

I've tried trailing a bucket to help the tide win the fight, but it didn't have enough drag. Maybe I should get some sort of larger drogue...

Pete