What weight NG anchor for a 20ft yacht?

[GHA]

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Oversized anchors are a recipe for a slipped disc or worse when your windlass fails, and actual weight in the anchor is irrelevant compared to the weight of a decent amount of chain deployed. It is the surface area of the anchor, how well it is set, and its tendency to break out under load that is important, and none of these factors are directly proportional to weight. I agree 100% with Jumbleduck - an appropriately sized NG anchor is all you need.

Round the coast near home very likely all you'll need, but you'll find very few experienced long distance cruisers who don't prefer to go up a size or maybe even 2. Most years there will be boats on the rocks from surprise thunderstorm with huge winds - people like to get the odds in their favour as much as possible. When it really kicks off the chain will be off the seabed so anchor weight/size is all you have left.

All you need almost but maybe not all of the time....

Been done to death over the years on the forums.

A few hours will should sort out an emergency retrieval system from gear already onboard with leap frogging on halyard winches or whatever which doesn't involve extreme manual labour, good idea to think it through before the windlass fails (as it likely will..)tv

 

[webcraft]

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Alain Hylas (Spade inventor) lived on his boat and knew I intended extended cruising on mine. If he said 10Kg was plenty I was happy with that. 15 years have not proved him wrong.


- W

 

[GHA]

.
Alain Hylas (Spade inventor) lived on his boat and knew I intended extended cruising on mine. If he said 10Kg was plenty I was happy with that. 15 years have not proved him wrong.


- W

Sounds like a small boat from their sizing chart
Anchor SpecificationsWeight - 10Kg (22lb)
Surface Area - 600cm²
Material - Galvanised Steel
Dismantleable for easy stowage
Boat Specifications
Monohull
Length <25' (<7.5m)
Displacement <2T


Long term cruising where's the downside? Unless you are on some lightweight cat there just really isn't one, whats another hundred quid over five or ten years?

When another 80kt gust hits not many will be wishing they had a smaller hook...

 

[thinwater]

So long as we are all being silly...

Not so many years ago windlasses were not common, hence the desire for "lunch hooks." Many smaller boats do not have windlasses. If you add the weight of a windlass, cabling and solenoids, and all chain rode, the impact is hundreds of pounds near the bow. Not sensible in many cases, money aside. A windlass made sense on my cruising cat, but not on my tri. Not by ANY stretch on the OP's 20-foot boat. So let us consider the case of no windlass.

Vow not to use your windlass for 1 week of anchoring and tell us what you learn about the merits of proof coil chain and up-sized anchors. Just sayin'. The primary anchoring kit on my F-24 weighs about 30 pounds, rode and all. The kit on my 34-foot cruising cat weighed 300 pounds, including the windlass (which I MUST include). Both will hold in the same wind, though the cat was set up for slightly deeper water.

 

[RichardS]

I just picked up a few anchors and decided that the heaviest I could carry without giving myself a hernia was 25 kg. Once I had confirmed that it would fit on the bow it was a done deal.

I've never once thought that I should have bought a smaller one... But I now have another 25kg one. You can't have too much of a good thing.

Richard

 

[noelex]

So long as we are all being silly...

This is not being silly, That is a very sensible post, Thinwater.

The largest anchor that you can comfortably handle (both boat and crew) may be a small anchor (relative to the boat size).

In this case it is simply a matter of managing within the limitations of the equipment. You can still cruise and have a great time. I know because my first yacht fell into this category.

The mistake I see on the forum is posts trying to pretend there are no compromises involved: “Small anchors have the same holding power as larger anchors”.

 

[webcraft]

Sounds like a small boat from their sizing chart
Anchor SpecificationsWeight - 10Kg (22lb)
Surface Area - 600cm²
Material - Galvanised Steel
Dismantleable for easy stowage
Boat Specifications
Monohull
Length <25' (<7.5m)
Displacement <2T


Long term cruising where's the downside? Unless you are on some lightweight cat there just really isn't one, whats another hundred quid over five or ten years?

When another 80kt gust hits not many will be wishing they had a smaller hook...

The Vega is 8.3m and about 3 tons. Hylas sold his interest in Spade and the manufacturer obviously wants to both cover their arse and make more money by selling the larger models.

I don't have a windlass, and can't find one for a hundred quid. And I would rather have a 10Kg Spade, Knox or Rocna than a 20Kg CQR or even Delta on any weight of boat. I will often leave the boat all day on the hook and go touring without worrying, and regularly sleep through F7 or worse with an occasional glance at an app on my phone to confirm we are still in the same place. We always are.

It's whatever makes you feel secure. I am happy with my solution, and experience so far has proved me right. My second boat is 5 tons and at the moment I have a 9Kg Knox as the primary anchor, with a 15Kg CQR as backup. If I fit a windlass I may go up to a 15Kg Knox or Spade as a primary as she is a slightly heavier boat, though the windage is very little more than the Vega and that counts as much as tonnage IMO.

To get back to the OP, my experience has led me to believe that a 6Kg Spade or Rocna on 6mm chain would be pretty bombproof for the OP's boat. Putting out more chain is more important than weight, whatever the size queens say.

Doncha just love anchor threads?

- W

 

[thinwater]

... Putting out more chain is more important than weight, whatever the size queens say....
- W

But puting out more chain IS weight. A LOT of weight if all chain.

My feeling is that there are three SEPARATE jobs to be done:
1. The anchor must set and have holding capacity. A chain does not hold anymore than a pulley holds a rope.
2. The rode must keep the pull relatively low and buffer gusts and waves. Any anchor is weak when lifted or we would not be able to recover them. Catenary and scope are the tools.
3. The boat must hold still, not yawing or hobby horsing. Any anchor is weakened by wiggling. Bridles, removing windage from the bow, and adding a riding sail are possible tools.

You can size the anchor or the rode to make up for a deficiency in the others, but the most elegant solution will separate the three functions.

 

[JumbleDuck]

Gradually, with time, you will come to the realisation, just by looking at the two anchors, that in any sort of normal substrate the 40kg Rocna will hold a higher force than the 5kg Rocna before it starts to drag. It’s truly an amazing revelation, magic in fact.

But that's not what he's saying. He is saying, correctly, that holding power is only a potential figure. Actual tension in the anchor cable comes from wind and water forces on the boat..

 

[MM5AHO]

I'll be at kip and I'm in the market for a 9kg Knox. Will there be any deals?

Yes

 

[noelex]

He is saying, correctly, that holding power is only a potential figure.

I agree. The maximium holding power cannot be measured until the boat starts to drag (or more correctly just before it starts to drag). As we want to avoid dragging, we hope the figure remains a “potential figure” rather than actual known value for the particular substrate and conditions we are anchored in.

Actual tension in the anchor cable comes from wind and water forces on the boat..

This is also correct. The only relevant point is an otherwise identical but larger anchor will hold a higher tension before it starts to drag than an smaller anchor, if all other things are equal (assuming the substrate is not unusual such as rock).

 

[Neeves]

This is also correct. The only relevant point is an otherwise identical but larger anchor will hold a higher tension before it starts to drag than an smaller anchor, if all other things are equal (assuming the substrate is not unusual such as rock).

Why do you think the smaller anchor is inadequate in the first place.

The smaller NG anchor is that size recommended by the manufacturer.

The manufacturer has increased the safety factor by 2 times for his anchor cf the previous generation, call them Delta/CQR/Bruce

Insurance companies have made no moves to have the old gen anchor spread sheets changed.

The Classification Societies allow, I think its a 30% reduction in size/weight for SHHP anchors v HHP anchors

Yet you recommend everyone buy a bigger anchor even though there is no history of dragging NG anchors (some of which are sized based on manufacturer's spread sheet).

Survey Officer - working to Classification Society, legally enforced, rules can reduce anchor weight by, I think its 30%, for SHHP anchors (call them NG) vs HHP (call them Delta/CWR/Bruce).


Currently there is no consistent history of the NG anchors dragging. Nothing that says anchors dragged because they were undersized.

NG anchors are reported to drag, re Morgan Cloud, but the failure has nothing to do with inadequate size but inadequate choice of substrate and/or operator error.


Yet the consistent mantra is 'buy big' and as far as I can ascertain there is only a very subjective basis for this recommendation.

Why any one individual think they know more than manufacturers, insurance companies, Classification Societies and reported histories is very questionable.

Jonathan

 

[Neeves]

To illustrate

If the recommended sized anchor, Delta, CQR or Bruce (copy/clone), which are HHP anchors, for your yacht was 30kg then CMP/Manson/Anchor Right, who sell SHHP anchors (with twice the hold of HHP anchor), would recommend the same size Rocna, Supreme, Excel. This is average - there are specific variations. Spade tend to recommend slightly lighter models. However the Classification Societies would allow a 30% smaller anchor if SHHP endorsed - so assuming RINA/LR/AMSA certification still in place - a 20kg model.

If your yacht has been inspected by a surveyor for insurance purposes the surveyor would accept the CS requirements, of 20kg. If your yacht is in survey your 20kg anchor, where requirement for safety equipment are more rigorous than privately used vessels, would be accepted.

The buy bigger camp here would suggest buying at least the next size up, preferably 2 sizes up on the manufacturer suggestions, which may be a 35kg or 40kg model.

So you would replace a 30kg Delta, CQR with a 35kg or 40kg Rocna (and some would suggest even heavier).

Do not forget - the insurance company will be quite happy with your 30kg Delta - and it is they who will pay out when your yacht is a right-off.

The weight difference is not much, between 30kg and, even, 40kg. But the weight difference between 20kg and 40kg is significant, with commensurate differences in cost - and this without any quantitative justification, no industry support, no history of failure - nothing.

The 40kg anchor will demand better chain (why anticipate needing more hold if you do not upgrade the chain). The chain can be better because it bigger or because it is stronger (G40 rather than G30). You are now thinking about a bigger windlass, heavier duty cables (which would be wise as a 20kg Rocna filled with mud is chickenfeed compared to a 40kg Rocna filled with mud). And all this on recommendation counter to professionals in the field.

Yes - I love anchor threads - fear to the forefront.

It is easier to fool people than to show them they have been fooled (Mark Twaine)

Jonathan

 

[noelex]

Yet you recommend everyone buy a bigger anchor

No, to be clear my recommendation for the primary anchor is to buy the largest anchor both the boat and crew can comfortably manage.

This general recommendation is a good starting point in my view. I sugested exactly this to Chris in my first post in this thread. This advice is only for cruising boats that intend to anchor overnight reasonably frequently.

Chris has pointed out in the first post of this thread how inconsistent and flawed the anchor tables are. On his boat if he chooses the very capable steel Spade, the manufacturer recommends a 10kg model. On the other hand, if he chooses the (in my view much less capable) Delta, the manufacturer recommends a 4 kg model.

 

[JumbleDuck]

No, to be clear my recommendation for the primary anchor is to buy the largest anchor both the boat and crew can comfortably manage.

For my Hunter 490 (1000lbs + crew displacement) that would be a 25kg aluminium spade, which the makers say is suitable for monohulls up to 30 tonnes.

 

[noelex]

For my Hunter 490 (1000lbs + crew displacement) that would be a 25kg aluminium spade, which the makers say is suitable for monohulls up to 30 tonnes.

You need to consider not just weight of the anchor, but the physical size. A 25kg aluminium Spade is a very long and wide anchor. The aluminium construction makes it much larger than the same weight steel version. I cannot imagine it could fit on your sized yacht, let alone fit comfortably.

Despite the fact it is an aluminium anchor, even the weight is a lot to manage and stay within the definition of “comfortable”, especially with only a small foredeck. Do you lean out of the foredeck hatch to deploy the anchor?

But you are the owner and know your boat. If you believe such an anchor could still be managed comfortably, I agree with your point that fitting the largest anchor you can comfortably manage would not be sensible in your case. I suspect the rule breaks down on other very small, and probably very large cruising vessels as well.

PS I admire you for cruising and anchoring overnight in a small yacht such as this. I almost purchased a Hartley T16 when younger, which is a plywood yacht of a similar size to yours. In the end I bought a slightly larger yacht in which my girlfriend (now my wife ) and I managed many extended cruises and had a great time.

 

[ghostlymoron]

I've only had OG anchors: Danforth, Bruce and CQR and experienced no problems holding on the Welsh coast. I always anchor in areas with known good holding shown in pilots and almanacs. Having said that, I now have a Guardian which is a Fortress lite which, being aluminium, is very easy to handle.
I've never used reversing to set the anchor but have relied on the wind to set it, often anchoring 'on the fly' with Genoa set and rode flaked out.

 

[NormanS]

I've only had OG anchors: Danforth, Bruce and CQR and experienced no problems holding on the Welsh coast. I always anchor in areas with known good holding shown in pilots and almanacs. Having said that, I now have a Guardian which is a Fortress lite which, being aluminium, is very easy to handle.
I've never used reversing to set the anchor but have relied on the wind to set it, often anchoring 'on the fly' with Genoa set and rode flaked out.

Oh! The present generation of motor boaters with auxiliary sails won't like that. Their NG anchors can tell whether the load on them is applied by the wind or the engine.

 

[webcraft]

r
I've never used reversing to set the anchor but have relied on the wind to set it

Then IMO you have been a very lucky boy if you have never dragged . . .

Why on earth would you not use the engine to set your anchor? What do you do when you anchor in a flat calm but the wind is forecast to get up to F6 overnight?

- W

 

[RichardS]

Then IMO you have been a very lucky boy if you have never dragged . . .

Why on earth would you not use the engine to set your anchor? What do you do when you anchor in a flat calm but the wind is forecast to get up to F6 overnight?

- W

I'm not recommending it as a method ..... but surely the anchor will set progressively as the wind increases in strength?

Richard