Anchors

[IanCC]

Apologies.

Assuming an anchor has dug in and held presumably its holding power is a function of its cross sectional area.

Yet when i look through the manufacturers recommended anchors for my Nic 31, 6.5t. there seems to be a broad range of cross sectional area for tbe different anchors recommended.

From spade 20kg at 1000cm to viking at 743, via knox 690 and rocna 1030.

Currently sporting kobra 14kg but feeling underdressed.

Thoughts?

 

[Tranona]

I will kick off.

Area is just one of the variables - shape, angle of flukes, angle of shank examples of others. Empirical tests show most NG anchors of similar "weight" have similar ultimate holding power.

 

[Boathook]

Any of the new generation anchors. If you are are going to store it on your bow roller I would go with whatever fits best out of the new ones.

 

[thinwater]

Apologies.

Assuming an anchor has dug in and held...

There you go. No two anchors dig in and hold in the same manner, so there can be no such assumption. There are similarities between anchors of similar design, but comparing based on area or weight in isolation is ... pointless.

 

[NormanS]

Oh No!

 

[IanCC]

Oh No!

Thanks for all input.

 

[Dellquay13]

Oh No!

Watch out with those fisherman patterns, someone will be along shortly telling us to buy a Herreshoff

 

[LittleSister]

People used the traditional rock-tied-on-the-end of a bit of rope for millennia. In those days, though, men were men, etc. All these newfangled anchors are just a cunning ruse on the part of The Man to part the honest seafarer from his/her hard earned!

From spade 20kg at 1000cm to viking at 743, via knox 690 and rocna 1030.

Currently sporting kobra 14kg but feeling underdressed.

Never mind what the spreadsheet says, does the Kobra do the job?

As others have said, the holding power depends on a range of factors in the anchor design. Most importantly, however, those different factors, and their combination, will interact in different ways with the particular seabed, and will depend on the latter's nature. Hence different anchors will have holding power advantages in different conditions. There are none which will be at an advantage in all circumstances.

As Neeve and others have argued, too, holding power alone (even if one could devise a universal meaningful measure of it, which no one has) is not an adequate indicator of the advantage of a particular anchor.

As with boats themselves, there is no one single factor that will determine success. It's a matter of balances, compromises, and what you are trying to achieve (e.g. easy setting vs. riding out the ultimate storm, etc.).

Assigning numbers to something is often mistakenly regarded as making things more 'objective'. Oftentimes it serves merely to obscure the subjectivity involved in selecting what's measured, how it's measured, and the intervals into which measured values are divided/reported, etc.

 

[Aeolus]

My Seamaster 925, a couple of feet and about a ton shorter/lighter than yours has, so far, touch wood etc. etc. been fine with a 25lb CQR and now with a 10kg Rocna. Your 14kg Kobra seems pretty heavy to me.

In your shoes, if I decided to change anchor, I would go with the manufacturer recommendation for my boat.

 

[IanCC]

People used the traditional rock-tied-on-the-end of a bit of rope for millennia. In those days, though, men were men, etc. All these newfangled anchors are just a cunning ruse on the part of The Man to part the honest seafarer from his/her hard earned!




Never mind what the spreadsheet says, does the Kobra do the job?

As others have said, the holding power depends on a range of factors in the anchor design. Most importantly, however, those different factors, and their combination, will interact in different ways with the particular seabed, and will depend on the latter's nature. Hence different anchors will have holding power advantages in different conditions. There are none which will be at an advantage in all circumstances.

As Neeve and others have argued, too, holding power alone (even if one could devise a universal meaningful measure of it, which no one has) is not an adequate indicator of the advantage of a particular anchor.

As with boats themselves, there is no one single factor that will determine success. It's a matter of balances, compromises, and what you are trying to achieve (e.g. easy setting vs. riding out the ultimate storm, etc.).

Assigning numbers to something is often mistakenly regarded as making things more 'objective'. Oftentimes it serves merely to obscure the subjectivity involved in selecting what's measured, how it's measured, and the intervals into which measured values are divided/reported, etc.

Thanks for lengthy reply, very much appreciated. It's just the kobra doesn't sit in the bow without gouging the paint work. I bought it in a hurry as a good value anchor when i bought the boat because it only came with a very rusty cqr and i needed to move the boat a few hundred miles. Cqr now destined fir scrap.

Looks like i need new gen anchor that fits, which i think means manson supreme, perhaps 20kg.

 

[LittleSister]

Yet when i look through the manufacturers recommended anchors for my Nic 31, 6.5t. there seems to be a broad range of cross sectional area for tbe different anchors recommended.

From spade 20kg at 1000cm to viking at 743, via knox 690 and rocna 1030.

Currently sporting kobra 14kg but feeling underdressed.

Thoughts?

The Kobra recommended anchor for your boat is the 8kg, according to the manufacturers' table . You are three sizes up from that!

It would seem that, if anything, your anchor may be too large for your boat, rather than too small. While some hold that the larger an anchor the better, there is a risk that an oversized anchor will not be buried as well as the correctly sized anchor, which would actually result in a reduced holding power.

You ask for 'thoughts'. Mine are that you should stop worrying about your anchor, unless it fails to perform as you would expect!

 

[boomerangben]

Apologies.

Assuming an anchor has dug in and held presumably its holding power is a function of its cross sectional area.

Yet when i look through the manufacturers recommended anchors for my Nic 31, 6.5t. there seems to be a broad range of cross sectional area for tbe different anchors recommended.

From spade 20kg at 1000cm to viking at 743, via knox 690 and rocna 1030.

Currently sporting kobra 14kg but feeling underdressed.

Thoughts?

I think the area that really counts to an embedded anchor is the area of the shear plane within the soil above the anchor. To break out, the soil needs to fail across that area. Fluke area obviously counts but I think perimeter counts as well which split fluke (Knox, Fortress etc) seem to take advantage off. If you look at the big ship and rig anchors, they are large perimeter designs

 

[LittleSister]

Thanks for lengthy reply, very much appreciated. It's just the kobra doesn't sit in the bow without gouging the paint work. I bought it in a hurry as a good value anchor when i bought the boat because it only came with a very rusty cqr and i needed to move the boat a few hundred miles. Cqr now destined fir scrap.

Looks like i need new gen anchor that fits, which i think means manson supreme, perhaps 20kg.

Didn't see this post of yours before writing my previous reply. So you want to change your anchor anyway for non-performance reasons, Fair enough.

20kg!!! You may as well go with a rock of that weight on a string! You will have to balance the savings on gym membership with the costs of physiotherapy/chiropractor! Even Manson recommends only 16kg (twice the weight of the recommended Kobra), and that includes 'offshore' use.

 

[Tranona]

Thanks for lengthy reply, very much appreciated. It's just the kobra doesn't sit in the bow without gouging the paint work. I bought it in a hurry as a good value anchor when i bought the boat because it only came with a very rusty cqr and i needed to move the boat a few hundred miles. Cqr now destined fir scrap.

Looks like i need new gen anchor that fits, which i think means manson supreme, perhaps 20kg.

20kgs is not necessary. A 16kgs is the recommended size. Having said that the manufacturers recommend your current Kobra for boats up to 14.5m! (maybe a bit optimistic, but your boat is less than 10m and 6 tonnes). So unless you have a burning desire to spend £370 or so - why change?

 

[IanCC]

The Kobra recommended anchor for your boat is the 8kg, according to the manufacturers' table . You are three sizes up from that!

It would seem that, if anything, your anchor may be too large for your boat, rather than too small. While some hold that the larger an anchor the better, there is a risk that an oversized anchor will not be buried as well as the correctly sized anchor, which would actually result in a reduced holding power.

You ask for 'thoughts'. Mine are that you should stop worrying about your anchor, unless it fails to perform as you would expect!

Thanks for thoughts. I am struggling to find recommended. But agreed relative to loa. But tonnage wize i understand it is about recommended.

 

[IanCC]

20kgs is not necessary. A 16kgs is the recommended size. Having said that the manufacturers recommend your current Kobra for boats up to 14.5m! (maybe a bit optimistic, but your boat is less than 10m and 6 tonnes). So unless you have a burning desire to spend £370 or so - why change?

Thanks. Do you have a link for that? I am battling to find one.

 

[Tranona]

Thanks. Do you have a link for that? I am battling to find one.

Assume you mean the Manson sizing chart Here mansonanchors.com/us/anchor-calculator/ The Kobra from Force 4 quoting Plastimo.

While not everybody agrees with me size (or rather oversize) is overrated, particularly with NG anchors. These have typically twice the holding power of old style anchors like the CQR and yet the size recommendations are similar. So your Nic would have a 35lb CQR when new and a 16kg NG has twice the holding power, so why would you want a 20kg? Manson would recommend a 16kg for boats up to 11m and 8 tonnes before the recommendation would shift up to 20kgs.

All the development of anchors has been to improve the performance for a given weight (assuming steel) and yet many still think that additional weight is beneficial. There is a strong argument to go down in size/weight with a NG anchor. My Golden Hind is very similar in size to your Nic but a bit lighter at 5.4 tonnes design and had a 35lb CQR. I have just downsized to a 10kgs Epsilon and 6mm chain. I had a 10kgs Delta on my last boat which was similar displacement but much higher windage and never had any problems. Remember if you read the empirical data from tests windage is a major factor in the loads placed on anchors so low(er) windage boats like yours (compared with modern AWBs) put far less load on the anchor when wind increases to the point where you could not fully load even the recommended size, never mind the next size up.

The Kobra comes out reasonably well in the various tests and really difficult to make a reasoned case for replacing it.

 

[TNLI]

The first decision concerns the area available and how an anchor will fit. If you have a good windlass, forget about the weight and judge by size. So for example a 10KG Fortress might produce better holding in mud or sand than, my main anchor, a 15KG genuine steel CQR, BUT it's far too big. If you downsize to fit a smaller Fortress, the holding will fish up almost the same. Obviously if you recover anchors by hand, weight matters, BUT don't foget that alloy anchors seem to top the tables for bent shanks, and their lifetime warranty does not include bent anything.

If you need to anchor in a storm one day, don't forget that heavier anchors work better than light ones, AND, if you exclude finger trouble like too short a scope and stainless anchor connector failures, the main reason is the use of anchors that do not reset if they pick up weed whilst setting or dragging. The boats that dragged because they were anchored in mixed holding that included cobblestones, rocks or Gawd forbid heavy weed including kelp beds, were not using an anchor that would hold in such more difficult sea beds.
In reality no anchor will hold in every type of sea bed, that's why lunatics like myself who like to anchor in the more difficult anchorages, always use 2 anchors on 2 different rodes.

The UK's most expensive yachts, the Oysters seem to use the Lewmar Delta, as do many RNLI lifeboats. Any heavy plow anchor like the CQR also works fairly well in heavy weed, BUT they are no good in cobblestones and rocks. None of the so called new generation anchors are good inheavy weed cobblestones or rocks. That's why Herreshoff yachts, the most exppensive classic yachts around, carry a bronze 3 piece Herreshoff, and a bronze Herreshoff. Lewmar who make CQR's and Delta's really do know what they are doing, as do Oyster yachts and those companies do not sell boats with weak shanks, or dubious weeds performance. Not sure what Oyster recommend for a secondary, but it could be a Bruce, as that will work in cobblestones and rocks, BUT not in weeds.
So when you select anchors, try selecting them in pairs. My folding Herreshoff is a bad copy, but I can't afford the real 17lb bronze version as it costs over a grand, The Herreshoff is in effect a better version of a fishermans anchor, BUT they work well, (Average), in mud and not so well, (One third up from the tables bottom), in sand.

Don't forget that you might need a spare anchor for a long cruise or a lines to the beach situation, (Both bow anchors in use, with a stern land anchor in the form of a dug in Danforth, and a steel Danforth is a real good spare.
Finally you will never reinvent the wheel without making it weaker or breakable, so when you see a light weight copy that lists good figures in mud and sand, ask the manufacturer how it would do with a short rope rode, and if it's good for cobblestones, rocks or weed beds. Heavy commercial anchors are, and I tend to regard the genuine steel CQR paired with my Herreshoff as a real good pair. Also this forum is seriously good at providing duff anchor advice, Lewmar, the RNLI, Oyster yachts and Herreshoff yachts only fit the very best anchors. Oddly enough the thousands of boaters who anchor in very difficult conditions of tthe Western and North West coast of the USA and Canada can't be wrong, as it's very rare for a local boat to use anything apartfrom a CQR or Herrreshoff. Also the Herreshoff is normally a Luke copy.
CQR vs. Delta. Anchor Test Video # 124 - YouTube

Anchor Reset Tests - Practical Sailor (practical-sailor.com)

PS: All the new generation armchair boaters will now go nuts again, so ignore the advertising, the ranting and trolling, and buy the real thing!!

 

[KompetentKrew]

Looks like i need new gen anchor that fits, which i think means manson supreme, perhaps 20kg.

You're off your rocker, m8.

My 40' boat came supplied with a 15kg Bruce - in my opinion that is undersized for my boat, but nonetheless it has held me in gales, probably in excess of 50 knots.

The Bruce is an old-style anchor - just use an NG anchor of the right size. Going twice the weight that it should be is madness - I wouldn't be surprised if it caused you more problems.

 

[john_morris_uk]

….. so ignore the advertising, the ranting and trolling…

Some of the best advice for this thread. If any novice reads this thread, please go and read the INDEPENDENT anchor tests and make your choices sensibly. Steel or forged CQR anchors are no longer even in the same league as Spade, Rocna etc. Fishernan type anchors perform very badly except in dense weed but who cares.