Anchors, Guns and Strippers!!!!

[Izikalvo]

Originally Posted by noelex 77

Some anchor companies like to recommend small anchors. The anchor buying public tend to assume when a smaller size is recommended, this must be because the anchor has exceptional performance. For boatbuilders, an anchor company that recommends small sizes is particularly beneficial. The boatbuilder can then supply a smaller anchor and importantly a smaller windlass, bow roller etc, which will add up to considerable savings and it looks nicer in the photos . High volume sales to large boatbuilders are dominated by companies that are prepared to recommend small anchor sizes.

I think this trend started with the Delta anchor, but Lewmar at least make it clear (providing that you read the fine print) that their recommended size is only suitable for quite modest wind strengths.

Izikalvo, I don’t think your anchor size recommendations are realistic.

Viking recomend a 8.2 kg (18.1 lb) steel anchor for a 15 m (49 foot) sailboat, and claim this will be fine up to 42 knots of wind.

In addition, the website points out “We measure our anchors holding power in a very conservative way, meaning, they will hold better than what shows on the charts.” “If you are not sure, go one size lower according to your boat size and weight, you will still have very good holding power”.

One size lower would be a 5.2 kg (11.5 lb) steel anchor for a 49 foot boat!

Unfortunately, those new to boating and anchoring will read these recommendations, and considering they have been made by the anchor manufacturer are likely to be persuaded by what in my view is very inappropriate advice.

i understand what you are saying here, we have these questions all the time,
I do admit we have a marketing problem here, it is kind of like offering commuters to buy a car that uses one gallon of fuel per 500 miles from a young and unknown company, but the facts are facts and we cannot argue with them.
We are measuring our anchor's holding power with very strict rules.
doing it in the same beach spot over and over again using accurate loadcells.
According to our measurements, following the ABYC recommendation chart (can be found here) we recommend the size of boat to anchor.
We always recommend using anchors to fit the "heavy storm" level so by saying "If you are not sure, go one size lower according to your boat size and weight, you will still have very good holding power” we mean that.

there are many factors that determine the anchor's holding power, such as the size of the fluke, the angle of the fluke to shank and shackle hole, angle of the fluke to the seabed and so on, but weight is not one of them, see aluminum anchors for example.

So yes, we stand behind our words, and we truly believe in our product and its characteristics.

[GRIT]

OK, I'm in.

First off, we believe bigger is better, and we don't have a "planned" weak link. I don't know anyone who does.

I've read the Viking site, and didn't see much with which to agree. I could counter just about everything I read in that site, by pointing to anything ever written by Steve Dashew. I think the success of his sundeer and deerfoot designs, which seem to go off the beaten track more than most, give his opinion some credence.

We are full time cruisers, and can't always anchor in the perfect spot.

We've always used oversized, genuine, Bruce anchors. But they don't make them any more, so we had to choose a new brand. Presently, we have a Spade S200, ( because we can ), 80m of 10mm chain, 1700w windlass, 10mm thick solid glass backing plates under the 12 inch cleats, on a 15m catamaran. Max displacement of 10 tonnes. I'm hoping the weak link is the front 2 meters of the bows being ripped off.

I don't care that someday I might have a windlass breakdown, I'll deal with that if it happens. But every day we're at anchor, I know if we drag, it isn't because I cheaped out on ground tackle.

Cheers all.
Paul.

[Lodesman]

Originally Posted by Mike OReilly

But again, in the real world of actual anchoring, a heavy anchor will set easier than a lighter one (for a given design).

Within a given design, and assuming the same material (ie both steel rather than steel vs aluminum) I'm not sure how you figure a larger anchor should set easier? The new-gen anchors use geometry or extra weight in the tip to put the pointy-side down. I'm assuming then that the amount of weight at the tip over the contact area at the tip determines the digability (if that's a word) of the anchor. I don't know if any anchor makers give the contact areas of their various anchors lying on a flat surface. My gut feeling is that the "buoyancy" that any given seabed will provide to any anchor that lands on it is the same in terms of weight/area. That said, any size anchor of a given design should have equal ability to set.

[wsmurdoch]

Originally Posted by Lodesman

How does one determine the safe holding limit of their cleat, even with a nice thick backing plate? Given the alleged holding strength of new-gen SHHP anchors, the weak link could very well be the fibreglass around the cleat.

The best testing that I know of is https://www.boatus.org/findings/16/

[GRIT]

If you lay an anchor on the ground, it it's setting position, and put your hand, palm down, under the tip, you'll see how a 55kg anchor digs harder than a 15kg anchor. Not all substrates are soft sand.

A new generation anchor, pivots as soon as tension is applied to the chain, so that the weight is on three points. The shank end, the tip and the heel. That is the position that counts; what I called the setting position.

I would suggest you watch some of the anchoring videos kindly made by "panope".

Cheers.
Paul.

Originally Posted by Lodesman

Within a given design, and assuming the same material (ie both steel rather than steel vs aluminum) I'm not sure how you figure a larger anchor should set easier? The new-gen anchors use geometry or extra weight in the tip to put the pointy-side down. I'm assuming then that the amount of weight at the tip over the contact area at the tip determines the digability (if that's a word) of the anchor. I don't know if any anchor makers give the contact areas of their various anchors lying on a flat surface. My gut feeling is that the "buoyancy" that any given seabed will provide to any anchor that lands on it is the same in terms of weight/area. That said, any size anchor of a given design should have equal ability to set.

[Lodesman]

Originally Posted by GRIT

If you lay an anchor on the ground, it it's setting position, and put your hand, palm down, under the tip, you'll see how a 55kg anchor digs harder than a 15kg anchor. Not all substrates are soft sand.

No. You'll see that the 55kg anchor is heavier. Soft sand, hard sand, mud, whatever - the anchor dropped onto it will sink until the upward force equals the downward force, which for a semi-liquid (which is what the bottom is, for the anchor to be able to dig in) we can call that buoyancy. Anchor of same design and same material should have equal density, so the buoyancy should be equal.

A new generation anchor, pivots as soon as tension is applied to the chain, so that the weight is on three points. The shank end, the tip and the heel. That is the position that counts; what I called the setting position.

The Spade also employs a lead ballast, I believe - you should know.

I would suggest you watch some of the anchoring videos kindly made by "panope".

.

Why? Does he compare different sizes of the same anchor on the same bottom? Got a link?

[GRIT]

It's not often I hear anyone say a light anchor will set as well as a heavier anchor, of the same design. I have seen the differences first hand, and that has never been the case.

Sometimes theory and reality don't jive. Perhaps if bottom buoyancy was the only factor to consider, you'd be correct.

But, I respectfully suggest, your theory is flawed.

I'm not sure how the lead ballast fits into my comments, but yes, I'm quite aware of the attributes of Spade construction.

I see you're "out there, doing it", so I'm going to end my discussion with you.
I'm no more likely to change your mind, then you are to change mine.

Good luck.

Cheers.
Paul.

[slug]

Originally Posted by Lodesman

Within a given design, and assuming the same material (ie both steel rather than steel vs aluminum) I'm not sure how you figure a larger anchor should set easier? The new-gen anchors use geometry or extra weight in the tip to put the pointy-side down. I'm assuming then that the amount of weight at the tip over the contact area at the tip determines the digability (if that's a word) of the anchor. I don't know if any anchor makers give the contact areas of their various anchors lying on a flat surface. My gut feeling is that the "buoyancy" that any given seabed will provide to any anchor that lands on it is the same in terms of weight/area. That said, any size anchor of a given design should have equal ability to set.

To work an anchor needs a chisel leading edge and enough weight to push this chisel edge into the substrate

Once buried into the substrate the anchor needs enough fluke surface area
To generate sufficient bite

It’s as simple as that .....

How you accomplish this could be a 1000 entry blog

When choosing a lightweight anchor...kedge, utility ...choose the anchor with a very distinct chisel leading edge ...fast bite

[Mike OReilly]

Originally Posted by Lodesman

Within a given design, and assuming the same material (ie both steel rather than steel vs aluminum) I'm not sure how you figure a larger anchor should set easier? The new-gen anchors use geometry or extra weight in the tip to put the pointy-side down. I'm assuming then that the amount of weight at the tip over the contact area at the tip determines the digability (if that's a word) of the anchor. I don't know if any anchor makers give the contact areas of their various anchors lying on a flat surface. My gut feeling is that the "buoyancy" that any given seabed will provide to any anchor that lands on it is the same in terms of weight/area. That said, any size anchor of a given design should have equal ability to set.

I'm really not sure what you're trying to argue. A heavier anchor will more easily penetrate the substrate than a lighter one. Indeed, part of this is simply getting to the bottom through weeds, bottom debris, gravel, etc. So a larger anchor gets to the set position easier than a smaller one.

Once set -- which means being in the set position, with the tip and fluke beginning to dig in -- the anchor needs to be dug in to do much of anything. This is where anchor design comes in, but a larger anchor will always have a greater holding capacity than a smaller. Weight is the simple proxy for this factor (again, comparing apples to apples).

[Lodesman]

Originally Posted by GRIT

It's not often I hear anyone say a light anchor will set as well as a heavier anchor, of the same design. I have seen the differences first hand, and that has never been the case.

see below

Sometimes theory and reality don't jive. Perhaps if bottom buoyancy was the only factor to consider, you'd be correct.

But, I respectfully suggest, your theory is flawed.

Without data, theory, wild-ass guess to offer up? Have you done a side-by-side comparison of the same-design in different sizes?

I'm not sure how the lead ballast fits into my comments, but yes, I'm quite aware of the attributes of Spade construction.

That was a response to what appeared to be your patronizing dissertation on the mechanics of new-gen anchors. I referred to it as geometry, and understand the mechanics thank you. Some new-gen anchors also ballast as well as depending on geometry.

I'm no more likely to change your mind, then you are to change mine.

Good luck.

Well certainly if you're not willing to try and make your case with some sort of cogent argument. I'm willing to be convinced, but I don't take anything just on faith - I'm not much for religion.

From above - this is a clip from Spade's website:

The Manufacturer of the SPADE anchor never refers to an anchor's weight, but rather to its effective surface area. The remarkable efficiency of a SPADE anchor is due to the size and shape of its effective surface: SPADE anchors of the same surface area will have the same holding power, no matter the material of which they are made.

[Lodesman]

Originally Posted by Mike OReilly

I'm really not sure what you're trying to argue. A heavier anchor will more easily penetrate the substrate than a lighter one. Indeed, part of this is simply getting to the bottom through weeds, bottom debris, gravel, etc. So a larger anchor gets to the set position easier than a smaller one.

As I asked of Paul - you base this belief on...?

Once set -- which means being in the set position, with the tip and fluke beginning to dig in -- the anchor needs to be dug in to do much of anything. This is where anchor design comes in, but a larger anchor will always have a greater holding capacity than a smaller. Weight is the simple proxy for this factor (again, comparing apples to apples).

I refer you to the Spade website - surface area and design are factors and weight has nothing to do with it - according to them.

As the Viking site suggested - in "setting" the anchor you pull it, be it with horsepower, wind-power, current and momentum, whatever - some amount of force is used to plow the anchor into the substrate. We both (maybe all) agree that the amount of "hold" that comes from that set is dependent on the surface area of the buried fluke - not the entire surface area of the fluke, just what is buried. Viking suggested that if that buried section is just the pointy bit below the shank, then the anchor is more likely to become unset with a change in direction, and therefore take longer to reset. This seems like a reasonable theory, so it does suggest one limit the size of the anchor to that which will bury most of its fluke with whatever method you use to set the anchor.

[Mike OReilly]

Originally Posted by Lodesman

I refer you to the Spade website - surface area and design are factors and weight has nothing to do with it - according to them.

As the Viking site suggested - in "setting" the anchor you pull it, be it with horsepower, wind-power, current and momentum, whatever - some amount of force is used to plow the anchor into the substrate. We both (maybe all) agree that the amount of "hold" that comes from that set is dependent on the surface area of the buried fluke - not the entire surface area of the fluke, just what is buried. Viking suggested that if that buried section is just the pointy bit below the shank, then the anchor is more likely to become unset with a change in direction, and therefore take longer to reset. This seems like a reasonable theory, so it does suggest one limit the size of the anchor to that which will bury most of its fluke with whatever method you use to set the anchor.

As I asked of Paul - you base this belief on...?

I base it on my experience, on the experience of most cruisers, and on basic physics.

Once again, weight is a factor for initial setting. But what really holds is the force generated by the buried flukes. This is a factor of design and surface area. A larger anchor of the same design produces more force than a smaller when buried to the same degree. Weight is a proxy for these factors.

You seem to want to fight. I keep stating that burying the anchor is key. And if you cannot get the anchor sufficiently buried, this could be a problem. This is why you need to size your anchor such that it can be managed by the crew, and the boat's systems, without undue effort. Boat systems could include engine size, although experience (mine, and most other cruisers) is that this latter factor is less of a concern.

[GRIT]

I'm not sure what you found condescending, but it wasn't intended that way.

I have indeed had two of the same anchor. We cruised 6 years with a Bruce 15kg, and 8 years with a Bruce 30kg. The 30 kg certainly dug in much better in grass, and other difficult substrates. I did not test them side by side, but I hope you'll agree that 6 years experience with one anchor would give me enough insight to know if the second anchor sets better in different substrates.

I also feel your posts have had an aggressive tone; such is the way with the written word. I may have misinterpreted your meaning as well.

I'm of the firm opinion, that same design anchors set better as they get heavier/larger.

I'd be interested in measuring the volume of the little point on the end of my spade, to see if it's volume goes up in parallel to the anchor's weight.

Cheers.
Paul.

Originally Posted by Lodesman

Well certainly if you're not willing to try and make your case with some sort of cogent argument. I'm willing to be convinced, but I don't take anything just on faith - I'm not much for religion.

From above - this is a clip from Spade's website:

[Dockhead]

Originally Posted by Mike OReilly

I'm really not sure what you're trying to argue. A heavier anchor will more easily penetrate the substrate than a lighter one. Indeed, part of this is simply getting to the bottom through weeds, bottom debris, gravel, etc. So a larger anchor gets to the set position easier than a smaller one.

Once set -- which means being in the set position, with the tip and fluke beginning to dig in -- the anchor needs to be dug in to do much of anything. This is where anchor design comes in, but a larger anchor will always have a greater holding capacity than a smaller. Weight is the simple proxy for this factor (again, comparing apples to apples).

I agree and I would add to this that bigger anchors seem to set and hold DISPROPORTIONATELY better than smaller anchors. I have no idea why -- maybe the weight goes up out of proportion to the surface area or the pressure at the tip goes up, or something -- but in any case, I think most experienced sailors know this from experience, and it is also fairly well known that some kind of magic occurs over 100 lbs. This is particularly noticeable in bad bottoms and short scope. Note that sizing recommendations are based on ideal bottoms -- do you always have one?



Dashew writes extensively about this, and what he writes corresponds to 35 years of experience of my own. Dashew writes what most experienced sailors on here say -- put the weight into the anchor, not the chain, and make the anchor as big as you can possibly handle. When people laugh at it, you know you're getting close to the optimum size.


If the chain is not stronger than the max holding power of the anchor, then get a smaller anchor? What? No, get a stronger chain.

If your cleats are not stronger than the chain, then get a smaller anchor? Jeeze, reinforce the cleats or add a proper samson post.

Belay the chain with something as strong as the chain -- don't rely on the snubber for this.

This is not a joke -- your life my depend on getting all this right.

[rslifkin]

Originally Posted by Dockhead

I agree and I would add to this that bigger anchors seem to set and hold DISPROPORTIONATELY better than smaller anchors. I have no idea why -- maybe the weight goes up out of proportion to the surface area or the pressure at the tip goes up, or something

This is almost certainly the case, at least with some designs. I was recently deciding between a 55lb and 73lb Rocna Vulcan for my boat (decided to go with the 73 in the end). The 73lb anchor has 20.2% more fluke area than the 55lb according to Rocna's numbers, but it's 32.7% heavier (and I'm sure not all of that difference is in the bigger shank).