EFOC

[Kegan]

I was reading a couple Ashby articles, and it seems that EFOC affects more than anything else when it comes to penetration (he got better penetration with a 40# recurve and EFOC arrow than an 82# bow and normal/high FOC). I have a pretty high FOC (about 22%), but I really didn't think that made such a difference?

Thoughts by those who have actually killed stuff with primitive and traditional gear  ?

[Mechslasher]

efoc increases momentum, thereby increasing penetration.  the benefits to efoc are numerous.  another is better flight and a more forgiving arrow.  it's like throwing a steel rod and then throwing a dart of the same weight.  a dart has efoc and flies, will like a dart while the steel rod will tumble and rarely hit anything but the floor.

[zenmonkeyman]

With EFOC, there is very little shaft ahead of the center of gravity, which means much less penetration-robbing shaft vibration on impact.

[Barrage]

efoc increases momentum, thereby increasing penetration.  the benefits to efoc are numerous.  another is better flight and a more forgiving arrow.  it's like throwing a steel rod and then throwing a dart of the same weight.  a dart has efoc and flies, will like a dart while the steel rod will tumble and rarely hit anything but the floor.

That wouldn't be quite right (I'm splitting hairs ).  Momentum would be the same (at least initially), but a high foc may maintain it longer due to better flight.  But if you had two arrows with good flight, then you could have identical momentum at impact.  High FOC still may be better in this case too; if you have indentical momentum at impact, the high FOC may penatrate better because of the higher mass at the tip.  This would be especially noticable if you hit something and had a change of direction.  The tip of the arrow would be trying to go a different direction that the center of gravity of the arrow.  With a high FOC arrow, the center of gravity is closer to the tip...

[FlintWalker]

With EFOC, the weight of the tip pulls  the shaft through the animal allowing for less oscillation or flexing of the shaft, increasing penetration.
 With a low FOC, the shaft is pushing  the point through and will flex more while it's trying to do it.  More flex = less penetration.
  That's just my way of thinkin.


  I shoot a GT 55-75 carbon with 300 grains of tip weight from a 50# glass recurve.  I guarantee it'll out penetrate the same mass weight arrow with say...a 125 grain tip.

[skyarrow]

ok what is EFOC ? so i can understand this

[zenmonkeyman]

Skyarrow,

It's Extreme Forward Of Center -- It refers to the center of mass, or balancing point of an arrow being much closer to the front than the rear. 

[Kegan]

Thanks everyone . As I mentioned, I have 22.5% with a 250 gr point on a stiff shaft with big feathers (which would go up to about 23.5% if I went to smaller ones). I just didn't realize that it was more of an impact on arrow or bow weight.

But I have a little of all three, so I guess I shouldn't worry?

[skyarrow]

thanx zen now i think i understand what yall are talkn about so the more the COB is to the front with a heavy head the more the penatration of the arrow currect me if i am wrong ttyl         sterling

[zenmonkeyman]

Skyarrow, yes you've got the gist of it.  One thing to remember is if you're drastically increasing the weight of the point, you should go with a heavier-spined arrow because it's lot's harder for your bow to get it moving and the shaft will want to flex more on release.

[skyarrow]

sounds good i will not forget thanx for the info