Viking's Odin anchor vs Ultra and the original Viking anchor

[boomerangben]

Why does there HAVE to be movement to absorb the energy of the wind? When a gale of wind hits my house, it doesn't go anywhere.

Does it not creak at all when you get a howling gale? Even masonry moves a little bit but if not there’s always heat lost through friction and turbulence. But since steel and aluminium are elastic, they will move when you apply a force to them. Soil will also move when you apply a force.

 

[geem]

Does it not creak at all when you get a howling gale? Even masonry moves a little bit but if not there’s always heat lost through friction and turbulence. But since steel and aluminium are elastic, they will move when you apply a force to them. Soil will also move when you apply a force.

My house is two foot thick stone. Do you think that moves?
With regard to anchors, I can only imagine a small amount of movement left or right from a boat yawing around. I can't imagine how you can generate a twitching force when all you have in term of applied force is a chain. The chain has catenary and with a snubber fitted, there is only a cyclic force from yawing or if you have a ketch that doesn't yaw, the chain going tight and then slack as the wind gusts and lulls. If the anchor isn't dragging and the anchor is well buried, I can't imagine the load imposing itself on a well buried anchor.
Very happy for somebody to explain the physics of a twitching anchor, but at the moment, I don't see it

 

[thinwater]

Why does there HAVE to be movement to absorb the energy of the wind? When a gale of wind hits my house, it doesn't go anywhere.

Grammar. To absorb and to withstand describe two different actions, just as strong and tough describe two different characteristics.

 

[NormanS]

Grammar. To absorb and to withstand describe two different actions, just as strong and tough describe two different characteristics.

In a gale of wind, I'll be very happy if my anchor moves as much as my house.

 

[Neeves]

I did some rode tension tests at different scopes that was written up for Practical Sailor.

I simply placed a load cell between chain, with anchor at one end, load cell at the yacht end, no snubber. I conducted the test In a location exposed to the developing Seabreeze with a clean soft silica sand seabed. I was using an Excel anchor, 15kg. I power set the anchor, 2x 20hp - say 400kg of tension.

As the wind developed I recorded maximum tension with maximum wind speed, the two did not occur together the maximum tension was always after the maximum wind speed.

The maximum tension I recorded was a snatch of 850kg. At this point the snatches were frightening and I decided to terminate the experiment. It took ages for the anchor to pop free - it was very deeply set and secure.

There had been cumulative snatch loads building to the 850kg and once 400kg was passed (approx) the snatches were over and above the tension I had applied (resulting in the anchor to have been really deep set).

The tensions I recorded, or the snatch loads recorded, were the same tension being applied to the anchor and were well in excess of any tension 2 x 20hp can apply.

A conclusion was that the anchor had set more deeply (nowhere near its ultimate holding capacity of near 2,000kg). In oder for the anchor to set more deeply and for hold to increase - the anchor had to move, at least imperceptibly.

The test gave me the confidence to be able to say a 15kg Excel was good for a 38' cat with a 22'6" beam weight approx 7t and a modern AWB monohull of 45'/50' has a similar windage. There is no need to use a bigger Excel, or bigger anchor of similar characteristics, say Viing, Odin, Spade, Ultra, Rocna, Supreme, Fortress. I reserve judgement on Vulcan, I've never even seen one, and I leave a question mark over Mantus M1 as all the anchors I list, excepting Mantus, have a setting trajectory of around 30 degrees but Mantus sets at 16 degrees. Mantus may also set more deeply - but it needs twice the room to do so (room might be at a premium).

The other lesson was that if you are potentially subject to winds increasing to enable snatch loads of 850kg (shallow water, short rode, oscillating gusts (only 35 knots but building) causing yawing, you will do something to reduce the snatch loads - it is frightening - you wonder whether the yacht has been designed and built to accept such tensions. So before the snatches are 850kg - you will have set a second anchor, deployed all your chain, added a snubber or, in my case, moved. The alternative is your wife is on the phone to a divorce lawyer and/or your crew will mutiny. Imagine reversing your yacht, flat chat, into a brick wall - that's the sort of feeling. 850kg is just beyond the WLL of G30 x 8mm chain, not everyone uses rated G80 alloy shackles (3/8th" WLL of 2t)

Jonathan

 

[Neeves]

...

I never understand this approach to anchoring. Why set an inferior scope to set an anchor?
If you are in a tight anchorage and you intend to set 3:1 then fair enough but if you intend to set 5:1 then why not put 5:1 scope out before you power set the anchor? More scope provides a better angle for the chain with more of the engine power setting the anchor and less of it trying to pull the anchor up.
We see charterers reversing back with tiny amounts of scope and dragging their Deltas for fun.
One guy took 13 attempts in different parts of the anchorage everytime, as if the bottom was the problem not his technique.
We lay out the chain to suit the depth, add the snubber and power set the anchor. Job done. Currently on 4:1 scope with 30kt squalls. Anchor buried and several feet of chain.

If you do not know the seabed, and in all cases you don't 'know' any seabed, then if the depth is say 7m and you need an 8:1 scope you will need to deploy 60m of chain. If the anchor does not set you need to retrieve the lot and try again. If you deploy at 3:1 you only need to deploy 20m of chain and only retrieve 20m. I know which is quicker and easier to retrieve.

You only need look at a sandstone cliff laid down under water so see the amount of variation that is possible - sand seabeds are not perfect - they vary - and might also contain organics, seaweeds, driven into your anchorage in a recent or historic storm)

If the anchor does not hold at 3:1 scope - you know the seabed is questionable and maybe there is somewhere nearby that is 'better'.

I'd rather find out quickly there might be an issue or my Chardonnay might be warm before I can even tastes it!

Our windlass, Maxwell, retrieves metres of chain in seconds - blink your eyes and the Boomerang is at the bow roller.

Each to their own

If your technique works for you, go for it - but no need to be righteous- there is no 'one' right way.

 

[Neeves]

In a gale of wind, I'll be very happy if my anchor moves as much as my house.

If you power set your anchor using your auxiliary engine then if you are subject to a Gale you can guarantee the tension developed under a Gale will be a higher tension than the tension at which you power set. The increased tension imposed by the gale will set your anchor more deeply - it will move. Accept reality

If you are unhappy with reality - you need a bigger engine (or maybe a better prop).

But don't worry about it - you have been doing what you do for decades - not realising that in reality your anchor can and will move due to the powers of nature.

Jonathan

 

[geem]

If you do not know the seabed, and in all cases you don't 'know' any seabed, then if the depth is say 7m and you need an 8:1 scope you will need to deploy 60m of chain. If the anchor does not set you need to retrieve the lot and try again. If you deploy at 3:1 you only need to deploy 20m of chain and only retrieve 20m. I know which is quicker and easier to retrieve.

You only need look at a sandstone cliff laid down under water so see the amount of variation that is possible - sand seabeds are not perfect - they vary - and might also contain organics, seaweeds, driven into your anchorage in a recent or historic storm)

If the anchor does not hold at 3:1 scope - you know the seabed is questionable and maybe there is somewhere nearby that is 'better'.

I'd rather find out quickly there might be an issue or my Chardonnay might be warm before I can even tastes it!

Our windlass, Maxwell, retrieves metres of chain in seconds - blink your eyes and the Boomerang is at the bow roller.

Each to their own

If your technique works for you, go for it - but no need to be righteous- there is no 'one' right way.

Its so easy to recover chain with an electric windlass. I can understand somebody with no windlass, reluctant to deploy 5:1 as they might not get a set and need to pull it all back up.
As to 8:1, we would never routinely use anything like that. It would have to be storm conditions for us to consider that much chain. In most anchorages, you would swing into boats close by. Most cruisers seem to use 4:1 or 5:1
In a difficult sea bed the improved angle of the chain at 5:1 compared to 3:1 could mean the difference between the anchor setting and taking full engine revs in reverse and not setting at all. Why would we move if we can set the anchor successfully.

 

[Neeves]

Modern anchors, some if not all - Rocna, Fortress, Excel, Spade (to name a few) will set (accidentally) or intentionally at 2:1. You may need to show some patience but we have set our anchors at 2:1 as have other member(s). I would not recommend it if you have the room or your mental arithmetic might be at fault - but modern anchors are much more forgiving than Delta and CQR.

We will quite happily set at upto 10: if there is room and the forecast conditions are exceptional. But we only draw 1m and we only carry 75m of 6mm chain. With, only, 2 -3m tides (sometimes the weather seems to influence tides more than the moon) round Tasmania and 10m tides on the Coral coast - 10:1 at low tide needs a slightly different set of rules.

If we have a Storm warning we might also deploy 2 anchors in a fork and use shore lines - there is no set procedure - each anchorage needs a different evaluation (in the same way high latitudes needs different kit and different answers).

In the summer Tasmania has one Storm warning at least once a month, I've counted them , and I assume more frequently in the winter.

We also sailed in areas where we might not see another yacht for days and to get, say 4 together, would be really quite an exception.

Not every member here crosses the Atlantic (nor goes to Tasmania or Australia's Coral Coast) and what works in the Caribbean might be impossible in other locations.

Jonathan

 

[Neeves]

Modern anchors, some if not all - Rocna, Fortress, Excel, Spade (to name a few) will set (accidentally) or intentionally at 2:1. You may need to show some patience but we have set our anchors at 2:1 as have other member(s). I would not recommend it if you have the room or your mental arithmetic might be at fault - but modern anchors are much more forgiving than Delta and CQR.

We will quite happily set at upto 10: if there is room and the forecast conditions are exceptional. But we only draw 1m and we only carry 75m of 6mm chain. With, only, 2 -3m tides (sometimes the weather seems to influence tides more than the moon) round Tasmania and 10m tides on the Coral coast - 10:1 at low tide needs a slightly different set of rules.

If we have a Storm warning we might also deploy 2 anchors in a fork and use shore lines - there is no set procedure - each anchorage needs a different evaluation (in the same way high latitudes needs different kit and different answers).

In the summer Tasmania has one Storm warning at least once a month, I've counted them , and I assume more frequently in the winter.

We also sailed in areas where we might not see another yacht for days and to get, say 4 together, would be really quite an exception.

Not every member here crosses the Atlantic (nor goes to Tasmania or Australia's Coral Coast) and what works in the Caribbean might be impossible in other locations

You might want to change locations if the swell unexpectedly enters the anchorage or some neophyte anchors to closely.

 

[Neeves]

Of neophytes

We found The Whitsundays too full of people at the bottom end of the learning curve and changed from the Tropics to sail Tasmania. Sailing The Whitsundays is one of the Australian dreams.

Situation

Man struggles to anchor near us. He asks, 'am I too close', I reply 'If you can talk to me you are too close'

Man looks pleadingly at us.

We have been watching his antics and are ready.

We reply - ' you stay where you are, we will move' - having sussed out the options. Sailing is meant to be a pleasure, we know our ground tackle - we've tested it. We use our knowledge to help encourage the neophyte.

Jonathan