When I was bowhunting both with traditional equipment and with compounds the term was never brought up. I just checked two of my three setups, my lightest bow is shooting 31" GT55/75's with 145gr Bear Razorheads and has a rough number of 5% FOC and my other bow is shooting 31" 2317's with the same broadhead and is roughly 4%. I'm having Wes Wallace build me another riser for my extra Stealth limbs which I was using the same 2317's and my existing riser but I just ordered some 75/95's , 200gr field points and some 190gr Tree Sharks to test for flight characteristics. This will obviously bring up my FOC but how much will it really affect arrow flight and penetration? Does it override arrow weight?
Shooting the weight bows you are I wouldn't worry to much about high FOC to get penetration assuming your just hunting elk and deer here in oregon?
4 or 5% is low FOC for sure but with the higher then avg weight you will be fine. I would try and get in the normal range of about 10-15% if your having any problems. I'm shooting around 14% I think with 50-52lb bows and don't have a problem with penetration on deer or elk sized game.
I like that quote from John Wayne.
Most books written by respected experts say that FOC should be under 10 and others say under 15%. It has to do with balance of the arrow.
How are you calculating that FOC? Are you doing it with the arrow itself or are you doing with with theoretical online computer calculators?
It seems that most of my FOC numbers are between 9 and 13%.
I doubt my shooting skill is good enough for it to matter. Until I am driving five arrows into an area the size of an apple then I probably shouldnt be concerned.
My hunch is that this is one of those areas where if you are in the generally accepted range then you are ok.
You might want to check to see if your numbers are within that range that would be ok. Also verify that your calculations on FOC are correct to begin with. There are so many small factors that can skew the results.
How about with stabilization, I have my bows tuned and have good arrow flight but every now and again I'll make a bad release and get some fishtailing, will the higher FOC help stabilize the arrow faster?
I used the arrows themselves and the formula in Byron Fergusons book. I was 4" and 5" forward of center which I thought it was funny my percentage basicly equaled my difference. The exact numbers are a 31" arrow so the 1/2 way point would be 15.5 and the balance point was 19.5" and 20.5".
I am with bearsfeet, Awhile back I got caught up in all the EFOC hype, then one day thought I would put an arrow together with the proper GPP total arrow weight and have never thought about EFOC since. All my bows are 60#s +. So no matter what I am going for dont worry about penetration. You do need some forward weight, you dont want the backend of the arrow telling the arrow where to go.
I find that arrows with an foc of 16 to 25% are more accurate. ymmv
Wapitirod,there are a couple different ways of measuring for FOC and none are wrong as long as you always use the same formula for comparison.The one that I use puts your FOC at 12.9% and 16%.That formula can be seen at Tuffhead's site and is the one used by OL Adcock,Doc Ashby and others.The difference in formula's is why yours sounds very low.It isn't.
You can read more about it on the Tuffhead site and probably find your answer.People who have tested it,like OL,say they found no measurable gains till they hit 19 %.I'm not good enough to see it then but can when it hits the mid 20's.I don't think you will see any gains but you can read up and see what you think.I don't think you will hit 19% with that much point weight on that shaft.
I shoot wood and my spine requirements make EFOC impossible with my bow; so I have quit worrying about it and focus on good tuning and shot placement.
Yep. Jim B is right. I get the same results. As you note, back in the day, we didn't worry about FOC. In fact, whether we knew it or not, most of our setups were pretty close to 10% because that's what a standard broadhead (most of which weighed 125-135 grains) yielded on a standard length wood arrow, say 28 or 29 inches BOP.
That's still a good FOC to shoot for, at least as much for good arrow flight as penetration. Much less than that and good arrow flight can become a problem.
I've made and hunted with a few high FOC arrows (about 25%) and I must say I'm impressed. Very good arrow flight and excellent penetration.
Long story short, you have plenty of arrow and FOC in your current set up to do the job, but it's always fun to experiment.
"How important is your FOC?"
Apparantly you can get by without knowing the ratio. I have no idea how my wood arrows work out. They have metal heads and little plastic nocks & light feather fletch so I know the C.O.G. if forward of the measured middle. ;)
Not near as important as the bangwagoneers will lead you to believe.
Matters little if you have a host of other things wrong. There's a lot more important things to worry about. I worry more about my shooting accuracy than all the nit picking folks started worrying about since the start of the internet.
Unless you are shooting long distances it's going to really be hard to see a lot of difference in arrow flight bro. Especially using a heavier draw weight bow like you do. I like to stay between 10-15% myself because i shoot out to 40 yards a lot. once you start getting above 15% FOC you'll notice your arrows taking a sharper nose dive as it gets down range.
once you get below 8% FOC you'll notice a lot more effect on flight in a side wind or any minor obstructions a lot. hitting a leaf with a 15% FOC arrow will cause a little tail wag, but continue on pretty straight. where an 8% FOC arrow will deflect easier.
With your heavy draw weight. FOC & EFOC where they are factoring in momentum vs KE will not effect penetration at all unless you are hunting Rhino's. IMO
Years ago, most of us determined our "FOC" by just checking to see if the balance point of the arrow was ahead (toward the point end) of the center point of the shaft. It was as simple as balancing the shaft on your finger and just looking to see if the length from your finger to the point was less than the length to the nock.
I'm a mathematician by training but sometimes we get too caught up with details and complicate our lives with trying for a number or % rather than just good results. KISS!
Arne
Thanks guys that helps alot. I also just received my subscription to Traditonal Archer and I ordered the past 4 issues. I finally got a chance to start flipping through them after I posted this last night and I found an article on this subject from the fall of 2011 issue. They had a formula that worked with the same numbers Jim came up with. It sounds like I'm in the ball park and what I'm trying for with my shooting is to become proficient out to 40yds for when I'm hunting the more open country of Eastern OR for mule deer and elk.
I wouldn't worry about it if I were you. I personally like a bit higher foc than what you have but have killed quite a few animals with old wooden shafts and 125 grain broadheads. Apparantly no one told those deer or hogs that a low foc arrow wouldn't kill them.
It is kind of funny, for years I've killed deer with a cedar arrow and a 125 grain head and never gave a thought to FOC.
Now I've read all the articles and question wether my setup will work, go figure.
Waipiti Rod
im not sure how you calculated FOC but by my calculations you are well above 10%
regards
Fanto
I either looked at the formula wrong or it was a different formula than the one you guys used and the one I found in Trad Archer magazine.
I don't know that anyone thinks you can't get the job done without high FOC, especially with higher poundage bows. I think high FOC helps penetration with lower weight bows like the ones I shoot. I also get great arrow flight. If I keep my overall arrow weight close to 10 grains per pound of draw, I don't see the nose dive Kirk mentioned. My RER shoots pretty flat to 40 yards, which is more than far enough to suit me.
If what you are doing is working, don't worry about it as long as you're happy with it. What works best for me, won't necessarily be the best for you or anyone else.
That brings up another question, when your figuring grains per inch on an arrow are you counting the finished weight with fletching, broadhead, etc or is it bare shaft? It's been since the early 90's I was really into shooting traditional. I started out shooting a compound instinctive and when I switched I just did the same things. I'd go by the spine charts and buy some arrows and then I'd buy whichever broadheads I was using at the time and I'd shoot. It was never anymore complicated than that but since I've gotten back into it and been on here it seems things have become more complicated.
I agree with Kirk. At short range you won't notice much difference. I shoot till 60 yards and then the difference becomes quite obvious. E-FOC gives a much less flat trajectory. Below the 8% your arrow becomes less stable. For me 10% is just about right.
On my Sitka 11/32 woodies I use 100 grains points which gives me a FOC between the 9.5 to 10%. I like a 10% FOC. I am going to develop some carbons. One of the starting points is a 10% FOC. BTW on the calculation form of Goldtip you can see that the recommended FOC is between the 8 and 10%.