Anchor Surface Area Comparison - Manson Supreme vs CQR

[Dockhead]

Originally Posted by SpadeAnchor USA

. . . the holding power of the anchor comes from its concave surface area.

We have been trying in vain to get some objective technical information to support the idea that a concave fluke holds better than a convex or plow-shaped one.

It's a question of soil mechanics and surely someone has done some actual research and actual engineering work on it. Can you share or point us to something? We're all sick to death of propaganda and hype and want some solid analysis.

I have personally owned a number of convex and plow-shaped anchors, as well as a couple of concave fluke anchors. In my personal anecdotal experience the concave ones worked much better. But I would like to know WHY.

[SA/USA]

My feeling is that the concave surface acts like a catch to hold on to the soil, whereas the plow shape creates a furrow in the soil much like the farmers did when preparing thier fields for planting. I don't know if anyone has done any actual research on this subject. Use the anchor that works best for you and your boat and gives you a safe and comforatable sleep, while at anchor.

[Maine Sail]

Originally Posted by SpadeAnchor USA

Yes surface area is very important when you are speaking of holding power. The weight of an anchor is also important for penatration power. That is why the Spade anchor has 50% of the total weight of the anchor in the tip of the anchor. The Spade therefore digs in instantly and the holding power of the anchor comes from its concave surface area.

If tip weight is soooo important then why doesn't my aluminum Spade A-80 set nearly as well as the SAME Spade S-80 anchor in steel?? If tip weight is really as imporant as Alain made it out to be then the A-80 and S-80 would perform identically and they often do not perform the same in hard bottoms, I own BOTH. I have one area where I can drag the A-80 30-40 yards four or five times before it finally sets. I can set the steel version, repeatedly, nearly instantly in this same spot. I think over all weight clearly has something to do with it too or two anchors of the identical size, shape & geometry would perform identically despite one being aluminum and one being steel? Tip weight is not the sole answer when I own two identical anchors that perform rather differently in hard bottoms...

[SA/USA]

Tip weight is important, but you are comparing two anchor that have the same holding power but different total weight. I agree that in this case with the type of bottom you describe, the overall weight of the S80 has better penatrating power than the A80, which is much lighter overall. 33# for the steel and only 15# for the aluminum.

[Ram]

Originally Posted by SpadeAnchor USA

Yes surface area is very important when you are speaking of holding power. The weight of an anchor is also important for penatration power. That is why the Spade anchor has 50% of the total weight of the anchor in the tip of the anchor. The Spade therefore digs in instantly and the holding power of the anchor comes from its concave surface area.

now you have me thinking I have the a140 I bought as a primary about 5 years ago and it really is not very good in anything except soft sand and great in mud- is it supposed to have a lead weight at the point? because mine does not it never has had one, it has a place where it could be filled with lead ?

[SA/USA]

Please contact me by phone so we can discuss your issue outside of the forum. I need to know where you purchased you anchor from.
My number is 321-409-5714

[S/V Alchemy]

Maine, have you considered a bridle or some sort of stem plate for the boat when using that mooring? I realize there's a limit to how much strain relief is possible when it's kicking up like that, but anything that could lower that chain and cushion it even a bit would be easier on the foredeck/anchor hardware, I would think.

[Dockhead]

Originally Posted by Maine Sail

If tip weight is soooo important then why doesn't my aluminum Spade A-80 set nearly as well as the SAME Spade S-80 anchor in steel?? If tip weight is really as imporant as Alain made it out to be then the A-80 and S-80 would perform identically and they often do not perform the same in hard bottoms, I own BOTH. I have one area where I can drag the A-80 30-40 yards four or five times before it finally sets. I can set the steel version, repeatedly, nearly instantly in this same spot. I think over all weight clearly has something to do with it too or two anchors of the identical size, shape & geometry would perform identically despite one being aluminum and one being steel? Tip weight is not the sole answer when I own two identical anchors that perform rather differently in hard bottoms...

I agree with this position, and in support I would add that my 25 kilo Delta anchor had a lead weight in its tip, just like a Spade I also owned. The two anchors could not be more different in their setting behavior. The Spade would practically rip the windlass out of the deck. The Delta never once set like that, and often wouldn't set at all.

I think it's clear from various people's experiences that total mass of the anchor is a very important factor in its setting and also holding behavior, with the Danforth-type anchors like Fortress being the only anchors which have holding power way out of proportion to their mass.

[Blue Stocking]

Has anyone thought to ask a farmer how much power it takes to plough or harrow a field. After all, these guys were the ones who started the science of digging in and moving dirt aside with various shapes of implements.
Dockhead's multiple requests got me thinking, who knows more about shapes and soil dynamics than farmers?
I bet Massey-Ferguson knows. I'm serious. And yes- I am aware that we are talking about underwater conditions.

[Kettlewell]

I know that a lot of real scientific research has gone into the development of very large anchors for things like oil rigs, though I suspect that a lot of it doesn't scale down well. Take a look here.

[Therapy]

Originally Posted by Kettlewell

In any case, I think many things about anchors and anchoring are based on seat-of-the pants engineering.

Yea, and some of it smells.

[Therapy]

Originally Posted by Dockhead

I think it's clear from various people's experiences that total mass of the anchor is a very important factor in its setting and also holding behavior, with the Danforth-type anchors like Fortress being the only anchors which have holding power way out of proportion to their mass.

That makes me think that a portion of a keel should be cut out and fitted with an anchor shape.

It could then be really heavy and reliable and no burden when sailing.

Now for a cat version one would have to have the ability to alter mass. Does Massey-Fergeson know about that?

There, I added cat vs mono. Someone else will have to add the gun part.

Seriously though - A heavy anchor that would fit up into a formed part of the hull or keel.

[Therapy]

Originally Posted by Kettlewell

I know that a lot of real scientific research has gone into the development of very large anchors for things like oil rigs, though I suspect that a lot of it doesn't scale down well. Take a look here.

I wonder how those can work with all those "blocking bars" like the bar on my Rocna??

[Kettlewell]

Seriously though - A heavy anchor that would fit up into a formed part of the hull or keel.

Some people have said that winged keels act this way when a boat is driven into the mud, and the bottom of some of these keels do look rather anchor-like to me.

[Kashmir cat]

Originally Posted by Ram

now you have me thinking I have the a140 I bought as a primary about 5 years ago and it really is not very good in anything except soft sand and great in mud- is it supposed to have a lead weight at the point? because mine does not it never has had one, it has a place where it could be filled with lead ?

Funny. Come to think of it, my first Spade anchor (A100) I bought in 1999 direct from Tunesia didn't have any lead either. I used it primarily in sand and mud as a second anchor, was thrilled with it, and apparently was none the wiser. That anchor was sold with my old boat years ago. The steel Spade (S140) on the boat I have now has lead but I guess I better double check the aluminum ones (A140, A80).