Anchors - Bigger is Better ?

[estarzinger]

Originally Posted by Delfin

I would like to understand the 'why' of that performance, which is the reason I think the discussion is worthwhile.

But none of you (seem to) know (have any science) how anchors actually work even in the big picture . . . how are you going to determine if that very small feature helps.

All you have are a collection of internally dodgy anchor tests which are not cross comparable.

You are all smart enough . . .you should be willing to acknowledge that basic fact . . . and then it should shape what you can usefully discuss

If not for someone else, then by all means, change the channel.

Yea, fine. I did explain just above why I had not done that . . . hope springs eternal that you guys will suddenly start acting like the intelligent adults I am sure you are when not on the internet arguing about anchors

Edit: and a small group of you essentially derail every anchor thread. This one was supposed to be about BIB. If you want to participate in an unscientific argument about anchor design, please start a thread about that (and name it something clear) and I will be happy to put it on ignore.
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[noelex 77]

Originally Posted by Cotemar

I would have added Fortress after Spade in the above statement, since almost every cruiser has one on board as a storm 2nd anchor.

I love the tag line. Fortress is an anchor even a woman can throw.

Yes I agree the Fortress is a great anchor, in many or at least some substaites it has the highest holding power of any anchor.

It is less suitable as a bower anchor because it occasionally does not reset with a change of wind direction and is a little more sensitive to the wrong substrate (such as weed), but every crusing boat should have one.

Really it deserves a category all of its own in that it will do some things so much better than other anchors.

[noelex 77]

I wandered around the boatyard and I could not find a Delta without a convex toe. I am not saying they don't exist (most anchors I see are buried in the sand ), but they must be very rare here.

Originally Posted by Delfin

That is not a Delta. Give it up.

I took the photo of the Delta with the ruler and I can assure you it is a genuine Delta in this photo at least. As Congo notes you can see the Simpson-Lawrence name and logo.

Delta anchors do have a small almost flat area (where the name is engraved) in the transition between the convex toe and the concave rest of the fluke. ( when viewed from underneath only). This can be seen on the photo in post 1383 and may be causing some posters to conclude the delta toe is completely flat.

I agree that the degree of convexity is slight and I cannot see this having much practical effect on the anchor performance. The Excel is a bit more convex again but the differences, compared to the Delta are once again are only slight.

I do agree it is worth searching for anchor traits that improve, or at least influence performance. Anchor testing and user reports both have some limitations and if we can have an intelligent discussion on anchor design I think this adds another valuable tool in selecting better anchors.

[Cotemar]

Originally Posted by noelex 77

Yes I agree the Fortress is a great anchor, in many or at least some substaites it has the highest holding power of any anchor.

It is less suitable as a bower anchor because it occasionally does not reset with a change of wind direction and is a little more sensitive to the wrong substrate (such as weed), but every crusing boat should have one.

Really it deserves a category all of its own in that it will do some things so much better than other anchors.

I have a new anchor design that would correct the Fortress / Danforth reset, weed and rock lock issues, but will leave that for another day.

[Delancey]

Thought you might find these images interesting.

They make it look to me that soil at the bottom of the sea, that is saturated with water (think about your concrete mooring block and displacement for a minute), is in fact is a fluid medium.

Take that however you will with regards to the condition of the underside of the fluke, be it convex, concave, or flat and whether you want your anchor to dive, or lift, or drag, or whatever shapes in a fluid medium do like your sails or keel or whatever.

The first two are of course from a Bruce Claw patent now thirty five years old. The second, also from Bruce, are from what looks to me like a self righting, unballasted, convex but spade-like design from 1996. Not sure what the date on the spade is, if before or after.

This anchor looks to me like a cast shank that extends down into the tip and then has a formed plate fluke welded on. Maybe Nolex can tell us this anchors fate in the market place, I am not aware of this having been produced but it looks a lot like the Davis Talon.

[Delfin]

Originally Posted by Cotemar

WOW, even the Delta drawing you posted, shows the convex bottom toe.

Let me make it easy on your eyes.

Here is a cross section of the 3D Cad model from the same drawing you posted above.

A walk on any dock will show you that however many times you post your drawing, it doesn't conform to what a Delta looks like.

[Delfin]

Originally Posted by estarzinger

Edit: and a small group of you essentially derail every anchor thread. This one was supposed to be about BIB. If you want to participate in an unscientific argument about anchor design, please start a thread about that (and name it something clear) and I will be happy to put it on ignore.
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Thanks for the bold font. Adds a lot of weight to your comment.

Is it possible that an even smaller group arrogantly insist that all conversations about subjects they are interested in follow only along the lines that map to their existing convictions?

To the question of is a bigger anchor better, perhaps the reason the posts go on and on is because it is basically asking how long a piece of string is. The result are the kind of unscientific responses you seem to deplore, with people offering their opinions on the subject. Kind of what Internet forums are about, I guess.

[Cotemar]

Originally Posted by Delfin

A walk on any dock will show you that however many times you post your drawing, it doesn't conform to what a Delta looks like.

I have real Delta Lewmar in my lap right now that shows the Convex Bottom toe. All the Delta anchors on my dock look the same.

It really is time to pickup a new set of glasses as you are missing what 99.999999% of everyone else is seeing.

Are you sure your not Congo's brother? Your starting to talk a lot like him.

[Richard_W]

I do not care one way or another but my 2007 Lewmar DELTA 22lb bottom toe looks flat ... maybe the design has changed, or is different for different sizes?

[Cotemar]

Originally Posted by Richard_W

I do not care one way or another but my 2007 Lewmar DELTA 22lb bottom toe looks flat ... maybe the design has changed, or is different for different sizes?

A design change would explain it or it may only be on the larger sizes like 45 lbs

[Delfin]

Originally Posted by Richard_W

I do not care one way or another but my 2007 Lewmar DELTA 22lb bottom toe is flat ... maybe the design has changed, or is different for different sizes?

No, they are all flat. I believe there is a 60# on our dock I'll take a picture of. And you're right - it makes no difference other than as an example of how convinced some can be about what is clearly incorrect. Hard to have informative conversations if basic reality is elusive.

[JonJo]

Another interesting facet of anchors, and I'd restrict this to 'modern' anchors to try to retain focus, is that every anchor maker produces anchor sizing charts. Such and such a weight of anchor for such and such length of vessel. Some of these charts are really sophisticated and include factors such as the weight of the yacht and whether its a multi-hull or not. They then all shoot themselves in the foot by having some let out cluase suggesting that for a whole variety of reasons you might want to buy a bigger model. So showing real confidence in their sizing charts



But despite all the detail, and sometimes lack of it, there is very little evidence they actually know what they are talking about. Find me an anchor maker who has a sizing chart and has any information to substantiate what they are recommending.


Reiterating what I mentioned before - Delta have a sizing chart (sorry gone back to an older design) and the Rocna or Mantus one is not that much different - despite the claims of superior (in fact 2 times) holding capacity. Worse - most new gen anchor makers are suggesting heavier anchors than historically were recommended - and then adding that caveat = if in doubt go one size larger.

And to that we then have BIB which is go 2 sizes larger than you think adequate. (Depends how you look at it but this might mean an anchor 3 sizes larger than the anchor chart).

It makes me wonder how people survived on anchor before, say 1990, using puny undersized anchors, 3 sizes too small.

But it would be interesting to have an anchor maker justify their recommendations with some real data and why with this superior holding capacity we have not gone down in weight - but up.

Fortunately it is impossible to believe this is a conspiracy on the part of the anchor makers to sell bigger anchors as there is no way they would agree, on anything.

Jonathan

[JonJo]

Noelex,

This is an 88kg Excel, Not only do many yachtsmen and women beleive in the excel they are sufficiently successful that they are being used in increasing numbers on substantial vessels. This is by no means the largest - I think they go up in size to 125kg or maybe 150kg

Tell me this is not a convex sole. Tell me it looks just like a Delta sole (and for once try to substantiate your claims).

[Fortress]

Jonathan,

Thanks for your input. We stipulate:

Boat size recommendations are for boats of average windage and proportions in 30 knots of wind, average bottom conditions, and moderate protection from open seas. For storm conditions we recommend using an anchor one or two sizes larger.

So let's use an example. According to the Horizontal Loads Table that is published by the American Boat & Yacht Council (ABYC), a 40 foot boat of average beam and windage will have a force, or load, against it of 1,200 lbs in 30 knots of wind.

Now if we go to our Selection Guide, for a 40 ft boat we recommend the FX-23 which will provide up to 8,000 lbs of holding power in optimal bottom conditions (hard sand), but only 1,200 lbs in soft mud (poor holding). if the shank / fluke angle is changed from 32 to 45°, then the holding power in soft mud will double to approximately 2,400 lbs.

So in 30 knots of wind, the FX-23 should hold that boat, of average beam and windage, in those bottom conditions.

However, if the wind pipes up to 42 knots, then the load will increase to 2,400 lbs, or double. That's ok if the bottom is hard sand, but in soft mud it might break free, so a larger model would advisable.

Brian

[Hydra]

I think that in the past, mariners accepted to drag anchor from time to time: when the bottom wasn't holding well, in severe conditions, etc. The windlasses on yachts weren't really powerful, so owners chose anchors on the light side. They compensated for this by having more than one anchor and they had the manpower to deploy this. Old books are full of explanations on how to set a second anchor.

IMO, the sizing in anchor makers charts is based on this "old" concept.

But the present situation is different: cruisers don't accept to drag any more, even on mediocre bottoms, they don't have any crew to stand watches at anchor but they have a big powerful windlass. Since the quality of chain has improved, it's logical to reduce its scantling and put that weight in a bigger anchor.

Alain