By Yuma Joseph Sobkoviak

When my wife walked in and asked what I was doing, a wise answer was needed. In front of me were a number of wooden arrows in various states of construction, an alcohol burner, glues of various persuasions, broadheads, field points, a digital scale, a note book and pencils along with rulers and my beverage. Having been married most of my life, I knew she was really asking why I was working on the brand new granite counter when I have been assigned other places for glue and flame. I quickly said, “I’m working on my FOC!”

I launched into a lesson on weight front of center, not slowing down enough for her to get a word in edge-wise. Surprisingly, she said she understood the concept and would I mind moving everything off the counter and into my own workspace. I did.
When I got hold of my first wooden bow and arrows, I nocked ‘em and shot ‘em. I kept at it until I stopped improving. I realized that tuning my arrows might help. So I set up my paper and adjusted my nocking point and spine and continued. Eventually, I stopped improving again and then I discovered FOC.

Eureka! This is the answer! But is it? Is weight forward of center important for wooden arrows? After all, did the Mongols worry about FOC? Did the English longbow men worry about FOC? Did the Native Americans? They seemed to do okay without fancy formulas, and it could be I wasn’t improving because I wasn’t going to get any better. Maybe I’m just not a very good archer, no matter how much I enjoy casting arrows!

FOC is important and here’s why: proper weight distribution along the arrow can improve penetration and lengthen the life of the bow. A heavier point combined with the correct arrow weight may penetrate deeper into the animal. Also, a heavier arrow with the properly weighted point will absorb more of the force at release, unlike a lighter arrow. This could increase the life of the bow since less force will be absorbed into the limbs.

Before we tackle FOC, let’s discuss total arrow weight. The bare shaft weighs X amount, the fletching and glue weigh Y amount, and the nock and glue weigh Z amount. These weights can be adjusted by changing the length and circumference of the arrow (to certain limits), fletching with various length feathers, and using nocks of different weights. The heaviest adjustment comes with the business end of the arrow: the field point or broadhead.

I belong to the school that believes arrows should weigh 9-10 grains per pound of draw weight, and I aim for at least 10 grains or more. So my 45-pound longbow needs arrows that weigh between 405 grains and 450 grains (or heavier). The arrow in figure 1 weighs 326 grains with no point, so even with a field point weighing 100 grains I am in the lower end of the ball park.
It is the distribution of this weight that is at the heart of FOC. Wiser people than I have decided that a good weight forward of center is 10-15 percent. This means that instead of 50 percent of the weight in the front of the measured center and 50 percent in the back, up to 65 percent in the front of the measured balance point might deliver the best performance.

If I measure my arrow from nock crotch to the end of the arrow (I removed the point but it doesn’t matter, just measure to the back of the point) I get 30.75 inches; halfway is 15.375 inches. Then if I put the point back on and locate the actual balance point (using a ruler or knife to locate the physical balance), I can measure how far in front of the measured middle this is (see figure 1).

For my 31+ inch arrows (with point), the actual balance mark with a 125 grain point is 3.5 inches in front of the measured middle point. Then dividing 30.75 into 3.5, I get 11.38 percent, or 11+ percent of my arrow weight is in front of the measured middle point. And, that's how you find FOC (see figure 1).

So I asked myself: Why am I shooting 125 grain field points and broadheads if they give me a low FOC? The answer is: because this is what the local archery stores sell. I perused a national retail outlet near my home and found no broadheads or field points heavier that 125 grains and many much lower. Why they do not carry heavier ones I do not know. So, to get some heavier test points, I used mail order.

I set up four identical arrows with 190 grain points, four with 160 grain points, four with 145 grain points, and four with 125 grain points (see figure 2); all had the same fletching and nocks. From an FOC perspective, my percentages were approximately 17, 15, 12 and 11 percent.

The real test came in the field. I wish I could tell you I saw a great difference off the bow. I didn’t. But, I did see a slight difference in drop (at 30 yards). The heavier points struck slightly lower than the lighter ones. I wish I could judge penetration, but my targets are well worn and it was impossible to tell.

What impressed me the most was that the higher FOC arrows (the 190 and 160 grain points) flew as well and as accurately as the lighter ones. Since there was no perceptible difference, I believe that going heavier is the right choice.

The real question for you is: Why do you choose the arrow components that you do? This applies to the archers who make their own arrows from scratch and to those who order them custom made. Perhaps gaining some weight up front will make a difference not only to your shooting pleasure (a heavier, slower arrow might group tighter for your shooting style) but also in your hunting. A heavier broadhead of the proper design might make the difference at your next adventure. The only way to know is to experiment.

Because we embrace primitive archery as a way of life does not mean we cannot use the tools that modernity gives us. I know a number of fine archers who are very accurate without math or scales or wives. Good for them. Me, I need every advantage I can get. And any excuse to gain weight sounds good to me.

(For more detailed information on FOC, see Dr. Ed Ashby’s article, “Understanding and Analyzing FOC.” It can be found on the Internet.)