Hi Gang,

So far I have 3 finished sitka spruce arrows. I built one to use as a test bed and experemented with the shaft length. At the full 32" they flew great and hit where I was looking with 175 grains up front. Total weight was 530 grains. But I decided to cut the length back a little to 29 1/2". They still hit where I look and the total weight is right around 510 grains. I did some math and came up with 17.3 grains per inch.

Is there a way to figure what the FOC% is? These are paralell shafts.

Thanks for your comments and words of advice.

Find the center point of the arrow ( this will be half the length from nock grove to BOP. Mark the arrow, now find the pivot point. measure the difference and that will be your FOC.

exampl: 30" arrow = 15" the pivot point from half way mark is 3" so your FOC is 10%

Thanks Sal can you make Whittingham?

Ok guys,

I found the center of the arrow measuring from the base of the nock groove to the very fron tip of the point. Measurement was 30 1/2" . Then found the pivot point and measured from the center point. That measured 5" . Now how do I do the math to figure out the FOC % ? I never was very good with math when I was in school.

Thanks Gang

so it would be 5 divided by 15.25 = 33% FOC

Distance divided by half the arrow length equals %FOC