Does a New Generation anchor need to be oversized?

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srah1953

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I've read through a whole pile of old threads on anchoring related topics. I'm thinking of changing from a Delta to a new generation anchor (Spade or Rocna), not because I expect to anchor in extreme conditions but getting older and more nervous every day, I want something that I can trust without worrying.
In the various posts that I've read there is generally a belief to always go bigger than manufacturers say. But I'm wondering if this applies more to old style anchors than new generation (NG) anchors (and also possibly to world cruisers, which I'm not). If the NG anchors dig in straightaway, is there any real point to bigger ones? Also, there was a post (possibly by Vyv Cox) where a comment was made on the actual strength of cleats and deck fittings (in mass produced boats) to extreme conditions, so was there a point in having an anchor stronger than the boat?
[I'm trying to leave aside cost but going from 20kg to 25 kg Spade is an extra £200+. Worth paying if necessary, but is it necessary?]
Anyway, thanks in advance for your thoughts.
Srah
 
Not for a Rocna. Their recommendations said (not sure today) that the sizing was sufficient for any conceivable wind strength. My 15 kg Rocna, the recommended size, has withstood 50 knots plus, which buried it deeply. I see no reason why it would not survive more.
 
srah1953 said:
In the various posts that I've read there is generally a belief to always go bigger than manufacturers say.
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Anyway, thanks in advance for your thoughts.
Srah
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Don't think that is the case actually. Long term , long distance cruisers quite often will go up a size on a new gen or sometimes lots bigger for a lesser hook, but that's cos sooner or later it may well help, like in a really nasty blow with nowhere to run to on a less than ideal bottom, or something like that. Just more insurance for very rare events and no options.
For the majority seems little point going up a size with a good hook.
 
Interesting question for me too Srah
I recently bought a (oversized) 15kg rocna for my 4 tonne 30ft yacht but I'm sending it back and swapping it for a 10kg following some advice from Jonathan and other various posts here. Also going to get 6mm rather than 8mm chain as the 6mm more than adequate .

It seems there was a risk of the oversized not setting correctly due to insufficient engine power. I had sort of fallen into the 'bigger is better' thing.
 
Some more details about your boat and anchoring aspirations would help.

If you and the boat can comfortably manage the extra 5kg, I would normally recommend ignoring the price difference and purchasing the better anchor, but £200 is a big price jump.

The extra 5kg means the anchor will have about 25% more ultimate holding capacity in most substrates if you believe the work of Professor Knox or about 20% if you believe the research by Vryhiof. There is long description outlining the evidence in post #15 here:
Don't drag your anchor!

This extra ultimate holding capacity will mean the wind strength will be higher before you drag. As the extra holding ability applies to most substrates and scopes this also means you can anchor in a less secure substrate or at a slightly shorter scope for the same ultimate holding capacity as the smaller anchor. There are exceptions such as rock, but these are rare. The abiility to safely use more anchorages rather than the ability to hold in stronger wind is the biggest benefits for most users.

Will you need these capabilities? That depends on how much you anchor and where etc. Personally sitting at anchor with storm Ciara on our doorstep, an extra 20-25% of ultimate holding capicity even if it costs £200 sounds like a good deal, even ignoring the greater security in poorer substrates or at shorter scopes, but most boats don’t anchor as much as we do so you need to decide this (and if you can comfortably manage the 5kg) for yourself.
 
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noelex said:
1) Some more details about your boat and anchoring aspirations would help.

2) This extra ultimate holding capacity will mean the wind strength will be higher before you drag. As the extra holding ability applies to most substrates and scopes this also means you can anchor in a less secure substrate or at a slightly shorter scope for the same ultimate holding capacity as the smaller anchor.
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1) The boat is a 40ft Sun Odyssey weighing 11 tonnes loaded. My aspirations are merely to be secure in all conditions, even if I hope never to experience them.

2) I thought the whole thing about new gen anchors is that they just dug in (see s/V Panope videos) and the more pressure the more they dig in (unlike a Delta which will plough through the ground) so how will they end up dragging?
 
How many people, when anchored in a gale of wind, have been heard to say, "Oh, I wish I had a lighter anchor"? ☺
 
srah1953 said:
I thought the whole thing about new gen anchors is that they just dug in (see s/V Panope videos) and the more pressure the more they dig in (unlike a Delta which will plough through the ground) so how will they end up dragging?
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New generation anchors are better, but they still have an ultimate holding capacity that is dependent on the substrate, scope etc.

Anchoring has become more reliable. Better equipment (and this includes a larger anchor) shifts the odds more in your favour, but it is not realistic to expect 100% security desite what is sometimes posted on the forum.
 
Interjecting with a dumb question, but is displacement or length the primary factor in ground tackle size selection? New boat isn't quite Fischer level chunky, but she's a heavy girl for her length. Looking at 20kg NG anchors by displacement, which it 50' territory.

She still seems to be in one piece after 45 years with mixed 8mm chain / rhode and a 15kg bruce of unknown date. But I am susceptible to advertising and want an NG at some point, but I figure I'll stick with 15kg.
 
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srah1953 said:
1) The boat is a 40ft Sun Odyssey weighing 11 tonnes loaded. My aspirations are merely to be secure in all conditions, even if I hope never to experience them.

2) I thought the whole thing about new gen anchors is that they just dug in (see s/V Panope videos) and the more pressure the more they dig in (unlike a Delta which will plough through the ground) so how will they end up dragging?
Click to expand...

There is no such thing as security in all conditions with any anchor but a similar sized NG will hold better than a Delta in the seabed conditions that suit it. The rest is anchor setting technique, choice of bay for the weather directions and (very recently for me) an anchor app to help sleep.
 
People who are interested enough in their anchor setup to spend money on a NG anchor are probably also quite likely to decide to increase size at the same time.

FWIW we bought a 33ft boat that came with a 10kg Bruce, we decided to upgrade to a Rocna and at the same time err on the cautious side and go for 15kg.

We took this anchor with us to our next boat, 39ft, and this has securely held us in 30kt+ winds. Not the greatest test I know, just that's all the experience we have of it so far. And despite being entirely happy with this setup, we are relegating the 15kg to a kedge, and have a 25kg Rocna to go on the bow this season.

I'm not entirely convinced by the argument that an anchor can be too big to set well.
 
ryanroberts said:
Interjecting with a dumb question, but is displacement or length the primary factor in ground tackle size selection? New boat isn't quite Fischer level chunky, but she's a heavy girl for her length. Looking at 20kg NG anchors by displacement, which it 50' territory.

She still seems to be in one piece after 45 years with mixed 8mm chain / rhode and a 15kg bruce of unknown date. But I am susceptible to advertising and want an NG at some point, but I figure I'll stick with 15kg.
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Prof. John Knox did a great deal of work on this topic. His findings, forming his expression for rode loadings, were that although the wind acts upon projected area, in practice it made no significant difference to use the length of the boat, which is more convenient.

The displacement of the boat does not play a part in his expression. Logically, once the boat is afloat the weight is supported by the water, so has no effect. Its mass presumably is significant in yawing and pitching but does not feature in the expression.
 
Anchors are mostly described by weight. But weight of anchor isn't what you really need, its holding power.

If all anchor models (across all brands and designs) were described by holding power (or the force it takes to plough the anchor in the sea bottom), then the selection of an anchor for a specific boat would be much easier. But when the difference in holding power to weight ratio is as much as five to one (best NG anchors compared to worst older designs), then specifying by weight will always be problematic.
I don't think that its necessary to "buy one size bigger", but it's hard to argue with that comment by NormanS, about no-one in a storm wishing they had a smaller anchor.
 
I went smaller - the 20kg Bruce was too heavy to bring easily onboard. The 15kg Vulcan has held well.
 
Entering the mine field that is an anchor thread ...

After cruising for some 40 000 miles with CQRs, we invested in a Kobra of the same weight as our current CQR. I wouldn't exactly call the Kobra a NG model, but compared to a CQR of equal weight, it has a much larger surface area at the business end, is weighted at the tip. Overall, it invests more of its weight in the actual business of keeping the boat in place. It certainly sets much quicker than a CQR.

To penetrate a substrate, requires a certain amount of "force per square inch". Hence, pointy (small area) and force (weight) works. All NG anchors invest weight where it counts: at the tip.

Once the anchor has penetrated, a large surface area is required to give as much holding power as possible. All NG anchors have relatively higher surface areas than the traditional types.

Consequently, I do believe that the manufacturer's claims that their NG anchors can be lighter than traditional anchors is correct.

Most anchors, traditional and NG, and when properly sized and shaped will normally hold considerably more than is required to keep the boat in place once properly set; providing a decent bottom and scope of course. The thing with the NGs is that they seem to set more easily and quickly. IMHO.
 
you started some thing now Srah no sooner Johnathan rises up he be on to it .

has a full time cruiser I think it boil down to one thing.
the type of cruising/ anchoring you going to do .full stop

if your a weekend sailor plan to anchor so short period or a cruiser who only interested in staying at anchor in reasonable winds and heading for a marina when the forecaster not looking good , a recommencement size anchor and even a small chain will do the job
but if like us and willing to sit any thing that comes our way for every day , nine months each year .
I be looking at investing in good ground gear, no matter what people write here or youtube video because at the end of the day its going to be you sitting out real blows and not some one who good at writing article and googling stuff .
you don't want you next posting here to say that you lost your boat because your anchor didn't hold.

my bet is most people here very rarely see 30 kts of wind and stay at anchor , and I can tell you that I have anchored with a few that post here and any sign of a blow and their off to find a marina or at less a mooring buoy , because they don't trust there anchor to hold and that's fine, I rather that then them dragging on me or anyone else.

when you sitting on a boat and one min your bow is facing the sky the next its dipping in the water you won't be thinking about the extra cost of a over size anchor.
the £200 extra cost is two night in a marina so in reality peanuts.

too many boats as lost each year because there anchor didn't hold or some other boat drag
 
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