My D.I.Y. Cobra Drift Anchor

In moving water, the leading edge is what causes the anchor to "hold" on the bottom.  The lip of the flat side is what drags and finds purchase on the bottom. In still water like a lake I don't think it would matter

In moving water, the leading edge is what causes the anchor to "hold" on the bottom.  The lip of the flat side is what drags and finds purchase on the bottom. In still water like a lake I don't think it would matter

is the leading edge the part of the anchor facing 1st into the current?

Imagine the pyramid anchor on its side with the eye (where you tie the rope)  facing down river (this is how they lay with a boat pulling on them in a moving river). I call the leading edge the bottom edge (of the face with the rope eye) that is in contact with the river bottom, this edge is what grabs and or plows itself into the river rock and holds the boat.

I think I am the one who needs the technical writing class

I guess that would make it not worth the effort to figure that whole angle out.   

Now, have we decided on a good weight?  Is 10lbs the magic number, provided shape plays an integral role in the holding action? 

Once I have an idea on the range of weight you want to play with, I can start constructing a mold and play around with.   I'm leaning heavy towards the tetrahedron shaped anchor as I can see it giving a wider leading edge for the same  volume of weight.   

Some designs also have a flat point (cut the top off a pyramid).  I would think this would give you an even bigger leading edge as well ...

-Allen

the small anchor is a 20lber.. it is what I use on my yak and it works fine.

the leading edge I am talking about is the edge at the bottom anchor face.. you can see in the pic how it would plow into the rocks and hold.

also the 3 sided vers the trad  4 side for comparison. 

on your existing anchors, what's the surface area [1/2 (base x height)] of the 3-sided anchor compared to the 4-sided of the same weight? length of leading edge? i could be wrong, maybe 3 sided is better for maintaining position?
(picture from http://www.mathgoodies.com/lessons/vol1/area_triangle.html)

Some designs also have a flat point (cut the top off a pyramid).  I would think this would give you an even bigger leading edge as well ...

-Allen

Wrong end Allen, unless you were referring to my first idea of reversing the anchor to still have the weight, but not as much bite. 

I guess the only upside to having movement would be in a sandy, or light gravel stream bed that allowed you to slowwly drag the the anchor down stream so you could fish while you bumbled along. 

I don't even know if this is a viable way to fish! 

Some designs also have a flat point (cut the top off a pyramid).  I would think this would give you an even bigger leading edge as well ...

-Allen

Wrong end Allen, unless you were referring to my first idea of reversing the anchor to still have the weight, but not as much bite. 

I guess the only upside to having movement would be in a sandy, or light gravel stream bed that allowed you to slowwly drag the the anchor down stream so you could fish while you bumbled along. 

I don't even know if this is a viable way to fish! 

Which end are you talking about then?

What I'm saying is that if you cut to "top of a pyramid" off (where the bottom of the pyramid is where the rope attaches), then you need to add more stuff at the bottom of the pyramid to make up for lost weight.  This effectively increases the area of the bottom of the pyramid.  Isn't that the side you are trying to increase the leading edge on?

-Allen

on your existing anchors, what's the surface area [1/2 (base x height)] of the 3-sided anchor compared to the 4-sided? length of leading edge? i could be wrong, maybe 3 sided is better?
(picture from http://www.mathgoodies.com/lessons/vol1/area_triangle.html)

I'm definitely not a math junkie, so me getting all into geometry is not a good idea.  However, just looking at say 10 pounds of lead poured into either 3 or 4 sided anchors of the same overall height, I would venture to guess that the 3 sided unit would have a wider face.  Maybe even much wider.  Whether this matters a whole lot or not, I don't really know?   
I do know that the 3 sided mold would be hella lot easier to fab up.   

Now, lets talk connection points molded into the anchor?   Mild steel, stainless steel, brass rod, galvanized chain, or other? 

bingo Pole !   you want a large "face" to plow into the river gravel and you want weight to give it enough drag for the face to bite.

Allen, I see what your saying. 
The mold itself could be formed with a flat bottom (like the one I made in the past), thus when the given amount of lead is poured it would push the leading edge to a wider point for sure.  This would all depend on how much of the point you remove, as to how much of the face will increase.   

Allen, I see what your saying. 
The mold itself could be formed with a flat bottom (like the one I made in the past), thus when the given amount of lead is poured it would push the leading edge to a wider point for sure.  This would all depend on how much of the point you remove, as to how much of the face will increase.   

I guess you'd need to be careful not to remove too much of the top, otherwise the pyramid could tip and roll.

-Allen

FYI-my yak anchor only weighs 9 pounds and it has been fine.

I guess the good thing about making molds, is that if the leading edge is too small, weight is too light, or any other factor renders the anchor less than optimal, we can fix it!      It's easy enough to melt it back down, and do something different with it. 
 
Hmmm?

Maybe I'll tinker with it a bit tomorrow?