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WithoutWarning
May 13th, 2010, 11:06 AM
Can one have 'to much' FOC ?
If so, what problems does it create if any ?
My arrows are 25.5" long from nock string groove
to insert fletched with feathers and 100gr. point.
My FOC is quite high. I haven't calculated it but,
just did a quick balance on my thumb nail and it
is only 7 -8 inches from the point. . .
Thoughts folks, Thx.

cruzctrl
May 13th, 2010, 12:37 PM
If your measurements are accurate your FOC is 18% -22% depending on if it is 8 or 7 inches from tip.
If these are carbon arrows that is not an uncommon number. But more importantly, if the arrows are working for you then you have no worries. The further FOC forward you will have more stability but less distance is how I understand the impact of FOC calc works.

If your tips are not glued in you could try a 75 grain tip just to move your FOC back a bit into the "normal" range if you are concerned with it. But if you are happy with how your arrows fly, I would not even bother.

bowhunterprime
May 13th, 2010, 05:37 PM
But if you are happy with how your arrows fly, I would not even bother.

+1
A high FOC will make your arrows drop quicker out at distances like 40+ yards. Are your arrows for hunting or targets? You could either get an 85 grain screw-in point (there are a lot of broadheads in the 85 grain weight) or switch to vanes or both. But still, if your arrows are flying good and you're getting good groups then don't fix what ain't broke!! -Chris

OneidaPest
May 13th, 2010, 06:21 PM
Chris is right old saying is if it aint broke don't fix it. The thing to remember is that as long as your arrow flight is good and consistent then everything is ok. FOC is for the arch of the arrow that is being shot. The closer to the center of the shaft the more parallel to the ground it flies. Thai will create less wind drag on the arrow out at long distances. Hope this helps out.

3children
May 13th, 2010, 07:07 PM
I believe you can have too much foc. Dr Fred has stated how great a higher foc is but with todays modern equipment it doesn't work that way. He shoots recurves and long bows. I have tried many different heads to go along with my GT20 smart shafts, the weight forward is built in and if you put too much foc on them, they will not fly as well as maybe 11-15% foc. Most people shoot the 100gr head anyways and the weight forward brings the foc in at, depending on length around 12% or higher.

TN.Frank
May 13th, 2010, 11:39 PM
I'm shooting an 85gr head and just switched to Max Hunter vanes to get my FOC up a bit. Now it should be 11%, which for me is working great. I think I've finally got my arrows all worked out as far as FOC, spine, tip weight, fletching, ect. Now it's time to practice, practice, practice until deer season opens up in late Sept. . :smile:

WithoutWarning
May 14th, 2010, 10:26 AM
Thx. for the responses fella's, thats great.
I really don't want to loose distance at longer
ranges/create too much arc.... so I am
going to add small weights to my arrows nock end
and bring the weight/FOC back up and
match the arrows these new ones are replacing.

The easiest fix would be to change tips, yes.
But even with the 100gr I shoot now, they are
only 5-7grs. over IBO so anything lighter will
be too light.

gluedudeguru
May 17th, 2010, 03:26 PM
Gold Tips calculator (type it into google)

Or

This is the formula that i developed from a few of the calculators

Caution: Not for the weak at heart... In math

=(((((0.5*Nw)+(2*(Vw+Ww))+(0.5 *Al*Sw)+((Sw-1)*(Pw+Iw)))/((Ww + Vw)+Nw+Sw+(Pw+Iw)))-(0.5*Al))/Al) * 100%

Nw-Nock Weight
Vw-Vane Weight
Ww-Wrap Weight (if applicable)
Al-Arrow Length
Sw-Shaft Weight
Pw-Point Weight
Iw-Insert Weight

(Inches and grains)

Vane weight equals total weight of all 3 vanes
If no wrap, omit all Ww
Arrow length is overall length
Shaft weight is bare shaft with nothing on it, no insert
Not needed, but weight additions from glue can be added to respected glued in components (ie, Vw = vane weight plus the glue)

bowhunterprime
May 17th, 2010, 11:24 PM
This is the formula that i developed from a few of the calculators

Caution: Not for the weak at heart... In math

=(((((0.5*Nw)+(2*(Vw+Ww))+(0.5 *Al*Sw)+((Sw-1)*(Pw+Iw)))/((Ww + Vw)+Nw+Sw+(Pw+Iw)))-(0.5*Al))/Al) * 100%


You say you got the formula from a few calculators? What exactly do you mean? What kind of math are you useing to get FOC? I tried to type it in but I'm not getting anything near a right answer. What FOC do you get for my arrow set like this:

Length (shaft only): 26.5 Inches
Weight per Inch: 8.2 Grains
Fletching Weight: 7.4 Grains (per one vane)
Nock Weight: 10.4 Grains
Wrap Length: 6 Inches
Wrap Weight per Inch: 1.2 Grains
Insert Weight: 14.8 Grains
Tip Weight: 100 Grains

dwagoner
May 18th, 2010, 04:41 AM
The easiest fix would be to change tips, yes.
But even with the 100gr I shoot now, they are
only 5-7grs. over IBO so anything lighter will
be too light.

sounds like too light a GPI arrow is your problem, all your weight is at the end with the point.

gluedudeguru
May 18th, 2010, 08:57 AM
That whole formula i gave earlier is beautifully inserted in an excel spreadsheet form/calculator. i just spent 20 mins trying to eflectively post it on here, no luck. I will be happy to give anyone that would like the file it, i guess just via email instead. Message me with an email and i will send it out until i can remember how to make a web page out of it.