FOC ??

[stack]

When trying to determine FOC% what is the formula you use. My arrows are 30" from nock to tip and my balance point is 2 inches in front of center.

[Friend]

FOC AMO Standard Formula

% FOC=  (( Dist. Knock throat to balance point  )   - 0.50)  X  100 /
                 ((                Shaft Length                         )    
     

         * Shaft Length – bottom of nock’s throat to end of shaft excluding insert and point (BH)


                     Normal FOC –   >0% to 12%
      High FOC -            >12% to 19%
      Extreme FOC -      >19% to 29.9%
Ultra-EFOC - 30%+

[katman]

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=000089

[damascusdave]

I simply use the 3Rivers version of the Stu Miller Dynamic Spine Calculator...that will get me close enough for my purposes...the truth is adequate FOC is not difficult to achieve

DDave

[McDave]

For a long time I measured FOC the way Friend says to do it and didn't worry about it.  But then I started using VAP's that have about 1 1/2" of outsert sticking out the end of the shaft before you get to the point.  I wonder if that should be ignored?  Does anyone know why we don't measure the whole arrow length, including the point, rather than excluding the point and adapter?

[katman]

McDave, point lengths can vary a lot, measuring to end of shaft standardizes it. Look at the VPA 3 blade and 2 blade, length can differ by .5" or more.

I think I would measure to the end of outsert.