Anchor size vs Chain weight

SolentSnowgoose

SolentSnowgoose

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Hi All

I know that there is a huge debate about "what is the best anchor" but I plan to update my anchor and chain prior to more extended periods of cruising and time at anchor and would appreciate some advice.

We sail a 37ft Snowgoose Cat and currently carry

Main anchor : 20Kg CQR + 10m x 10mm Chain + 50m x 18mm Octoplat ( we often lay with 5x depth of rope and hence have a large swinging circle)
Secondary : 45lb Fishermans + 25m x 8mm Chain + 40m x 16mm Octoplat ( acquired as a "Rock Anchor" for Scillies but rarely used )
Kedge : Fortress FX 11 + 10m x 6mm Chain + 40m x 16mm Octoplat ( Bought for smaller boat but AMAZING holding in mud/ sand)

I plan to replace the secondary with : Fortress FX 37 + 10m x 10mm Chain + 50m x 18mm Octoplat

For the main I plan either a new generation SHHP anchor ( Spade/ Rocna / Manson ) with extra 10mm chain & warp

However I don't want to add too much extra weight ( bad at the bow of a cat) so the trade off is either :

a) 20Kg SHHP Anchor with 25m x 10mm chain or
b) 16Kg SHHP Anchor with 30m x 10mm chain


Question ...

Given the advantage of SHHP anchors over the CQR is it reasonable to go down a size in order to have a bit more chain so that we can lay to all chain and reduce the swinging circle

Or is it better to put the weight into the anchor and lay to a bit more rope ... This is the way I am tending at the moment on the basis that the ultimate holding power depends on the Anchor once the chain is bar tight and the rope will then be more effective in dealing with snatch loads

Dare I ask on comments on the 3 potential SHHP anchors ... I like the Spade but its very expensive, I like the Rocna but am just a bit irritated by some of the comments by those promoting it and hence am now tempted by the Manson based on price / value.

All experience, comments and advice appreciated
 
There are others on here much better qualified than me to answer your question (particularly a guy called Neeves who might see your post). As regards anchor choice I can comment on the Rocna which for us works amazingly well in sand but in our experience is not so good in soft mud. We have 20kg on 36' heavy-ish monohull - I would not want a smaller one. We have an original NZ one so if I was getting another anchor I am not so sure I would go for a Rocna now. Have you looked at the Sarca which looks very good ?
 
Chain, chain, and more chain. You want to put 50-60m of chain on your main anchor. A fortress of a Delta will both do a good job as far as the anchor is concerned, but you need more chain.
 
Hi Bobc

Given no restriction in weight then I would happily put on lots more chain but with a Catamaran its really easy to overload them particularly with weight up front given the bow shape of the Snowgoose.

Hence I was looking for the trade off between chain weight and the holding power of the new generation SHHP anchors.

My understanding has been that the chain weight is great at creating a nice caternary and hence avoiding shock loads on the anchor BUT in the ultimate it was the anchor that does the holding and that the new SHHPs had much higher Ultimate holding power than the older Plough types like the Delta

Do you see no difference between the Delta and the new SHHP's

Mind you I agree 100% on the Fortress .... have just got my new FX37 ...its a thing of beauty !!
 
Given that the SHHP anchors claim 5 times the holding power of your CQR, then a 15 kg one should be adequate. As for chain, do you really need the weight of 10mm? OK you carry it already, so no need to change it.
My own philosophy is to drop two anchors and rodes (V mooring) when I think one, on a 5:1 scope, might not be up to it.
 
Chain does far more holding that you give it credit for. With enough chain, you could hold your boat in most things with almost anything you care to stick on the end. Most anchors work well whilst the shank is lying flat, it's when it gets lifted and anchors break free. If you've got 30m of chain sat on the sea bed and another 10m up to the boat, the loads needed to get you to the point where the anchor shank starts getting lifted are pretty huge.

I do get your point about weight in the boat though. If there nowhere you can store the chain closer to mid-ships?
 
I would not compromise on Anchor weight and go with the recommended size of the new types.

As for chain, we carry (Westerly Oceanlord) 80 meters of 8mm chain. I am told by Bradies chain that the strength is fine for a 12 ton 40ft boat. But to avoid the shock loadings when it's really blowing, you should use 20 meters of 16-18 mm nylon line with a chain hook, allowing a large loop of chain to hang down. You would be amazed at the amount of stretch in that amount of nylon! Far far better combination IMHO than 10mm chain.
 
Chris_Robb said:
..... But to avoid the shock loadings when it's really blowing, you should use 20 meters of 16-18 mm nylon line with a chain hook, allowing a large loop of chain to hang down. You would be amazed at the amount of stretch in that amount of nylon! .....
Click to expand...
Totally agree - we have a few metres of octoplait as a snubber and it is extraordinary how much it stretches when it has a large load on it.
 
RAI said:
Given that the SHHP anchors claim 5 times the holding power of your CQR, then a 15 kg one should be adequate.
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The SHHP certification is for 4x the holding power of a stockless anchor. As Sockless anchors hold so poorly in the smaller sizes used by yachts it is a pretty meaningless standard.
Another accepted definition is 12x the mass. A 35 lb anchor is required to hold a measly 420 lb ( at 10:1 scope) to pass the standard.

The better same size anchors will hold over 10x this or 5,000 lb (@ 5:1) in independent tests. The standard sets a very low bar in terms of holding.

If you make some assumptions about windage etc the SHHP requirement test to about 26knots of wind and that is being generous assuming an oversized anchor etc

So forget about the SHHP certification meaning what is says. I would not let it influence your anchor choice. However, the three anchors you have listed are all excellent and will do much better than your CQR. I think the Rocna/MS is just slightly better than the Spade, but others feel the opposite. If your bow roller will fit the Rocna/MS they are cheaper than the Spade and can be re galvanised.

To the main question:
The maximum holding for the lightest weight is with as much weight concentrated in anchor and as little as possible in the rode. In practice a chain rode is often needed because of chafe resistance and make your boat swing like others around you, but the goal of maximising weight in the anchor is a good principal especially for a cat.

G7 chain is an option to consider, you can usually reduce the chain size by one step and keep the strength identical.
 
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Bobc said:
Chain does far more holding that you give it credit for. With enough chain, you could hold your boat in most things with almost anything you care to stick on the end.
Click to expand...

I really wish people would stop writing this nonsense on the internet where inexperienced people can read it. Chain will not hold your boat. An anchor will hold your boat. The chain is there to connect your boat to the anchor, if you remove the anchor the boat will move. Try it!
 
SolentSnowgoose said:
Hi Bobc

Given no restriction in weight then I would happily put on lots more chain but with a Catamaran its really easy to overload them particularly with weight up front given the bow shape of the Snowgoose.

Hence I was looking for the trade off between chain weight and the holding power of the new generation SHHP anchors.

My understanding has been that the chain weight is great at creating a nice caternary and hence avoiding shock loads on the anchor BUT in the ultimate it was the anchor that does the holding and that the new SHHPs had much higher Ultimate holding power than the older Plough types like the Delta

Do you see no difference between the Delta and the new SHHP's

Mind you I agree 100% on the Fortress .... have just got my new FX37 ...its a thing of beauty !!
Click to expand...

Until recently I had a Snowgoose 37. We had 20kg spade, 30m of 8mm chain and 30m of anchor plait. This set up worked very well. I liked the Spade that much I have just acquired a 30kg one for my next yacht so have to sell the 25kg Rocna I am taking off?
The spade stowed well on the roller. We had total confidence in it as an anchor. Not as convinced with the Rocna hence the change.
 
FWIW we have had both Spade and Fortress FX37 on our 10 ton Rival. Both worked to spec. After 10 years of carrying 100m of 12mm chain for the bower we replaced it with 30m of chain and 70m of octoplait. Didn't notice any difference in holding power but did notice less hobbyhorsing due to lower wieght in anchor locker ....
 
lustyd said:
I really wish people would stop writing this nonsense on the internet where inexperienced people can read it. Chain will not hold your boat.
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+1 (unless you have a few miles of the stuff, but the other boats will not be impressed with your swing circle:))
Even if the chain is on the bottom it is still the anchor that is holding the boat in anything other than very light wind. The chain weight ensures the pull on the anchor is parallel to sea bed where the anchors holding is maximum, but even this effect disappears in moderate/strong winds and the fluke angle becomes primarily based on scope.
 
Another vote for the spade We have a 20kg on 50m 8mm chain and 50m octoplat (I like to fish in deep water sometimes!) for a 37' monohull (Westerly Typhoon). We sailed around Britain and Ireland this year anchoring >80% of the time and never dragged. We did move onto a mooring at Helford the night it blew F10 but have confidence enough to anchor most of the time on any seabed type. I also use a 10mm 3 strand nylon snubbing line of about 8 metres. This really does stretch and keep the snatch loads off the ground tackle, but is strong enough (about 1.6 tonnes IIRC).
 
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typhoonNige said:
Another vote for the spade We have a 20kg on 50m 8mm chain and 50m octoplat (I like to fish in deep water sometimes!) for a 37' monohull (Westerly Typhoon). We sailed around Britain and Ireland this year anchoring >80% of the time and never dragged. We did move onto a mooring at Helford the night it blew F10 but have confidence enough to anchor most of the time on any seabed type. I also use a 10mm 3 strand nylon snubbing line of about 8 metres. This really does stretch and keep the snatch loads off the ground tackle, but is strong enough (about 1.6 tonnes IIRC).
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I forgot to mention on the cat, we had a 12mm polyprop bridle with chain hook. The polyprop stretched like crazy and did a great job of keeping the cat head to wind. The mast located aft on the snowgoose also helps to put the windage where it helps. With this set up she would stay pointing into the wind very effectively. I also think this helped to reduce snatch loads
 
Wow this is great stuff

GHA said:
Actually, they're not really. in more extreme conditions when you really want the chain to be on the sea floor it won't be.
Check out this site..

http://alain.fraysse.free.fr/sail/rode/static/static.htm
Click to expand...


Thanks for this link I really appreciate being able to put some numbers to the problem ....( when I get time)

Thanks to all for the various advice ..my preliminary conclusions ( before running the numbers are )

1) Go for weight in the anchor not the chain ...(probably 20kg Spade)

2) Have a bit more chain (probably 25m) so I don't have to put out too much rope and be a pain in a crowded anchorage

3) have lots of Octoplat for deeper anchorages where there are potentially less boats around

and 4)

When it really blows up find a nice shallow river and dry out among the reeds :)

Oh ...yes just for clarification...

Agree 100% about use of bridle on Cat ....it makes the whole thing much more civilized at anchor, we still swing but don't "kite"

The only reason not to change down from 10mm to 8mm is the cost of a new Gypsy for my Lofrans windlass ....more than the chain !!!!
 
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lustyd said:
I really wish people would stop writing this nonsense on the internet where inexperienced people can read it. Chain will not hold your boat. An anchor will hold your boat. The chain is there to connect your boat to the anchor, if you remove the anchor the boat will move. Try it!
Click to expand...

I'm not suggesting that the chain holds your boat. I'm suggesting that chain has a big influence not only on keeping the anchor at a good angle to the sea bed to keep it dug in, but also that to has a big effect on damping out gust and swell loads. It's certainly not just "a way of attaching the anchor to the boat", otherwise why would anyone use it, and why would the MCA require a minimum of 60m to be carried on a charter boat?
 
Bobc said:
I'm not suggesting that the chain holds your boat. I'm suggesting that chain has a big influence not only on keeping the anchor at a good angle to the sea bed to keep it dug in, but also that to has a big effect on damping out gust and swell loads. It's certainly not just "a way of attaching the anchor to the boat", otherwise why would anyone use it, and why would the MCA require a minimum of 60m to be carried on a charter boat?
Click to expand...
Once the forces get up, when you really want a catenary, it does little.
 
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