weighing a delta

[jim99]

Much is said about one size bigger being one size better when buying an anchor, but this and other anchor guides suggest I go with the 6kg Delta for my 8.2 metre, 4.5T Vancouver. Even one size up, 10kg seems a bit small.

Searched the forum, found lots of positive comments about the Delta, but maybe owners can tell me if the ratings make sense.

cheers

 

[bluedragon]

I assume somebody has done the sums. The problem is we've all got used to heavy CQRs over the years; it may well be these smaller more efficient anchors can be smaller? I have a 6kg Delta on a 27ft 3.0T yacht, but as a second anchor. I'm going to try it on chain vs. the 25lb CQR at some point this summer. I suspect it'll hold just as well, but if buying new as a main anchor I'd probably go up to 10kg just to be sure.

 

[hylass]

[ QUOTE ]
Much is said about one size bigger being one size better when buying an anchor,

[/ QUOTE ]

I perfectly agree...

EXCEPT.. now, it is well accepted that WEIGHT has very few relation with the holding of the anchor, Holding is related mostly to the surface area of the fluke and to the shape of this fluke.

The "concave" surface is the shape which has the highest holding coefficient.

Weight for weight, they are anchors which have a much bigger surface area (and a much higher holding..)

web page

 

[snowleopard]

This table is a good guide. I have a 16kg Delta on a 40 footer and it has served me well.

 

[jim99]

bluedragon,
My main anchor has been a 35# CQR, which came with my boat, not so heavy in the grand scheme of things, but quite large for my little boat.
The beauty of where I live is the sea bottom is always sand, muddy sand or sandy mud and every anchor that has ever been invented seems to work brilliantly, everything sets and nothing drags. I don't need a CQR so heavy.
But then, of course, you move on to places that are not so perfect to anchor.

 

[jim99]

[ QUOTE ]
The "concave" surface is the shape which has the highest holding coefficient.

[/ QUOTE ]
But what shape has the highest "setting" coefficient? /forums/images/graemlins/smile.gif

 

[jim99]

Hey, you stole my table, though I'm sure I stole it from another thread and maybe from you, so no worries.

But thanks for your experience. I notice the table doesn't have any modern anchors beyond the Delta.

 

[craigsmith]

Our sizing chart: www.rocna.com/main.php?section=best&chapter=sizing&page=0

We recommend a 10Kg; 15Kg if you're really mad on security. Definitely a Delta 15Kg to be anything close to equivalent, especially in softer bottoms.

With anchors bigger is always better. If you can afford the extra cost and can carry the extra weight (and size everything else to do with ground tackle in proportion), then do so. The question then becomes how big is big enough.

 

[hylass]

[ QUOTE ]

But what shape has the highest "setting" coefficient? /forums/images/graemlins/smile.gif

[/ QUOTE ]

Good question Jim..

The shape which has the highest "setting" coefficient? is definitively not the one of the Delta:

When a plough anchor (Delta - CQR) falls upon the seafloor, it usually rests on one or the other side of the plough. At this point, the active surface of the fluke initially assumes this “putty knife” angle with respect to the seafloor. Ideally, the tip then encounters a mogul or soft spot, allowing the tip to penetrate. The plough then pivots, allowing the active anchor uper surface to assume the “chisel” angle which allows the anchor to completely embed itself. Should the seafloor be hard or covered in weed, the plough may simply scrape along the surface without penetrating. /forums/images/graemlins/mad.gif

The highest setting shape is the chisel’s sharp beveled edge designed to cut and shape a surface, usually at an angle greater than 90°, and up to 120 ° with respect to the direction of the pressure. This is, according to my common sense, an ideal angle of attack for an anchor fluke. Not shaving, leveling, scraping or spreading the surface, but actually digging in from an angle. No need for a sand dune or other unevenness to trip the fluke, no prayer for a soft area. Mixed with a sharp edged fluke or weighted tip, and in it goes.
/forums/images/graemlins/laugh.gif