I shot in a 3-D tournament with a young man 10 years ago that was continually losing or damaging his arrows. With a handful of targets still remaining, his hip quiver that had once held six shiny new aluminum arrows now carried only two badly damaged shafts. I figured he’d pack it in. But instead, to my shock, he took an arrow that was mushroomed from centering a tree branch and snapped it off an inch behind the point. He crimped the shaft closed to form a wedge tip. Without a point or an insert to provide front weight, the undaunted fellow went on to shoot at and actually hit a few more targets.

That archer’s arrow was theoretically unstable because its balance point was behind the physical center yet it still flew straight because of the large helical fletchings it carried. Had the fletchings been removed the shaft might have hit the target sideways or even tail first. That demonstration reinforced an important fact: arrow stability is related to a number of factors including fletchings, balance point and dynamic shaft stiffness. Here’s how these variables can be made to work more closely together to produce an accurate arrow.

HELICAL FLETCHING AND LOTS OF IT

As long as the tail of the arrow carries three big fletchings with a high degree of helical your arrows will stabilize quickly even if your bow isn’t perfectly tuned. Large helical fletching also reduces the affects of inconsistencies such as a slightly bent shaft or a nock that’s out of line.

All archers, but especially bowhunters, should choose their fletching conservatively. Four inches should be the minimum starting length for hunting arrows even with mechanical broadheads and five-inch fletching is even better. There is little place for straight fletching in archery – bowhunting or otherwise. An arrow needs to spin to be most consistent. It’s important to note that even arrows equipped with field points will plane if they come out of the bow other than dead straight. Helical fletching helps reduce this affect. With today’s drop-away arrow rests there is no good reason not to use fletching sporting eight degrees, or more, of helical offset.

FORWARD OF CENTER BALANCE POINT

Your arrow’s balance point will affect its trajectory – at least slightly. For example, an arrow that is “tip light” will remain a little more level in flight and will actually plane or sail along a flatter trajectory than one of the same weight but with a heavier nose. But, tip light arrows don’t correct quite as fast when they come out of the bow. The closer the center of gravity gets to the physical center of the arrow the less stable the arrow will be in flight. A slashing arrow pivots around its center of mass (balance point). The farther the balance point is from the fletchings the more leverage they have and the quicker they can bring the arrow back on line.

Here’s how you calculate Forward of Center (FOC) balance point and why you need to know this number.

Calculating FOC: Divide the overall length of the arrow by two. (Overall length is the distance from the bottom of the nock groove to the point where the shaft meets the insert. This should produce the physical center of the shaft. Now subtract this number from the balance point (with the point installed), a distance that is also measured from the bottom of the nock groove. Divide the remainder by the complete overall length. Multiply by 100 to express as a percentage.

The experts at Easton feel that an FOC value that is between 10 and 15 percent will produce the best compromise between stability and a flat trajectory for most hunting situations. The American Society for Testing and Materials have published a procedure for measuring balance point, and in it they state that a value of 9% is typical. But, they also add that the range can be as wide as 7% to 18% while still producing good arrow flight. 3-D shooters seeking a flatter trajectory often go a little lighter on the nose with many shooting arrows having FOC balance points closer to 6 percent.

The best way to achieve your desired FOC (to play it safe, let’s shoot for around 12%) is to try several different weight points until you hit the right balance. However, if you are sold on a particular broadhead that’s too heavy to permit the arrow to fall into the desired FOC range, you can change from feathers to vanes or vice versa if the head is too light. You can also change from aluminum inserts to lighter composite inserts if the FOC is too large.

DYNAMIC STIFFNESS

If your arrow is improperly spined your consistency and stability will suffer. The shaft selection charts published by the arrow manufacturers are a good starting point, but you still must experiment with various point weights to determine which one produces the tightest groups with your bow and your release technique. Changing point weight will also affect FOC balance point, so once you arrive at the proper tip weight you should retest your FOC. If it is outside the range from 10% to 15% you can add or remove weight from the back of the arrow (changing fletching length and style is the easiest method) to bring it back in line without greatly affecting dynamic stiffness.

A stable arrow will recover quickly upon leaving the bow and this makes it more consistent and more accurate. That’s a very worthwhile goal for any bowhunter.