Forward Of Center

[Critter]

I was reading a bowhunting magazine the other day, and I came across what I thought was a very easy way to determine the FOC of your arrow.
For some of you new hunters who don't know what FOC is, it's a way to determine what weight tip you should be shooting with your arrows.(Broadhead, or fieldpoint)
First, take your total arrow length, including nock and point. Take that number and divide it by two, and mark a spot on your arrow at that point. For example, if you had a 28 inch arrow, you would mark a spot in the center of your arrow at 14 inches.
Next, find something to lay your arrow on so that you can balance it perfectly. I slid the center drawer out on my desk and used the side of it. When you have it balanced, mark that spot on your arrow also. Take a measurement between the two marks on your arrow and divide the total length of your arrow by that number. For example, if the difference between your two marks was 3 inches, you'd divide 3 into 28 and end up with 9.3%. The author goes on to say that normal accepted ranges of FOC are between 7 and 10 percent. Mine ended up coming out to 13%.

Hope this might have helped a few of you out.
CRITR

 

[moosehunter]

OK, that part is easy enough to to but what does the percentage mean? If say, mine comes out to 9%, what weight does that relate to?

 

[NWBuck]

I'm guessing that they would suggest to goof around with the weight of the head until the balancing point is as near the center mark as you can possibly make it. For example, I just went out and measured mine and the balancing point was 2" ahead of the center mark with a 100 grain muzzy. This was an error of about 6% with a total arrow length of 33". However, since the balancing point was ahead of the center mark, the only way to bring it back would be to lighten the head. I doubt I'll make a change, but I may see how a 75 or 85 grain head flies on this setup. Kinda interesting really....

NWBuck

 

[Critter]

I think the whole idea is to have the proper percentage of total arrow weight a certain amount forward of center so the arrow follows the point when it's flying through the air. The way I invision it is in the same way you would tape a paper clip to the front of a paper airplane to get it to fly straight. I'm definately not an expert in this area, but I find it kind of intersting because a friend of mine dramatically changed the accuracy of his bow just buy increasing the weight of his broadheads. My FOC doesn't fall into the recommended percentage either, and I'm not going to change anything this fall, but I'm going to try a little heavier head after the season is over just to see the what the difference is. Maybe RUDD will read this and give us a some insight.

CRITR

 

[Rudd]

I have never messed around with this....seems pretty logical though. Any guineah pigs want to do some field testing?

 

[iabow]

CRITRGITR 13% I wouldn't worry about. From what I read 7-10% is for target shooting and I think it was like 8-13% for a hunting arrow. Mine is sitting at 11%. I have heard OLY shooters use this alot to change their point of impact, use diff heads to do diff things.

 

[203ntyp]

Check out bowjackson.com. You can calulate your arrow wieght, speed, kinetic energy & front of center.

 

[Guest]