Tips For Increasing Arrow Speed
October 13, 2010
"Oh man, I shot just underneath his belly!"
How many times have you heard this excuse from a bowhunting buddy? Or how many times have you uttered those words yourself when describing an unfortunate encounter with a buck during bow season?
Play this crazy game long enough and you'll experience that sinking feeling in your gut as you watch the fletchings on your arrow harmlessly tickle the white hairs of a deer's underside just before the arrow plows into the earth and sends the deer scampering off to live another day. Maybe you dropped your arm. That's something only time on the practice range can fix.
But maybe your range estimation was off by a couple of yards. Maybe the deer was 33 yards from your stand, and you aimed as if he was 30. Depending on how fast your bow spits out an arrow, that's enough of a difference to cause a low miss.
So the answer is to buy a new bow, crank it up to 90 pounds and shoot a super-light arrow, right? Not exactly. You need to have a draw weight that you can comfortably pull and hold for a minute or more, if necessary. And for some of us, that might only be 50 or 60 pounds. And while a super-light arrow definitely will fly fast, that doesn't mean it has sufficient knockdown power to push through hide, tissue and bone. The best hunting arrow is one that is light enough to fly fast, yet carries enough weight to punch through a deer
Rob Kaufhold, owner of Lancaster Archery Supply in Lancaster, Pennsylvania and a bowhunting and target-shooting coach, recommends bowhunters follow the International Bowhunting Organization's minimum standard for arrow weight of five grains per pound of draw weight. If you shoot a 70-pound bow, that means you want an arrow weighing no less than 350 grains.
"And that's as low as you should go," Kaufhold said. "For maximum penetration, you're better off with something in the 425-grain range."
No matter what bow or arrow they're shooting, most of the bowhunters Kaufhold deals with could get more speed out of their setups with just a few tweaks here and there. Pay close attention to what you put on your arrows and your bowstring, Kaufhold says, and it's possible to pick up anywhere from one or two feet per second (fps), or even 10 fps or more.
To illustrate how speed can be gained and lost, we conducted a series of tests under Kaufhold's direction. And here's what we found.
"Everything you put on the center two-thirds of your bowstring -- brass nock sets, a kisser button, string silencers -- makes the string heavier and robs you of speed," Kaufhold said.
We shot a 444.8-grain arrow from a Hoyt RazorTec set at 70 pounds. For the first shot, we placed two cat-whisker string silencers on the string, along with a kisser button, string loop for the release and a peep sight that connects to the cable via a length of rubber tube.
With those common bowhunting accessories on the string, the arrow left the bow at 258 fps. For the second shot, we removed the peep sight and rubber tubing, and replaced them with a peep that is simply tied into the string and is not connected to the cable. We also removed the kisser button and the two silencers. The same arrow then left the bow at 262 fps -- an increase of 4 fps just by removing and changing some string accessories. We probably could have gained even more speed, Kaufhold said, if we had reduced the length of the serving -- a line wrapped around the bowstring at the point where an arrow is nocked so that the nock doesn't damage the bowstring.
If you're shooting an arrow that's the proper weight for your bow, the noise the string makes at the shot shouldn't be excessive, which means you don't really need any silencers. But if you feel your bow is too loud at the shot, opt for small rubber discs to employ as silencers. They weigh less than the cat whiskers and cause less drag when you release the string.
Look at a bin full of arrows at any archery pro shop and you'll see arrows with short vanes, long feathers, decorative wraps and tips weighing anywhere from 75-125 grains. All impact an arrow's weight and flight speed. To test those impacts, we took three identical, 27.25-inch-long, Carbon Express Rebel Hunter 6075 arrows and fitted them with different accessories. All were shot from a Bowtech General, with a 29-inch draw length and a draw weight of 67 pounds.
Arrow No. 1 was tipped with a 125-grain field point and a 7-inch-long decorative wrap was placed at the nock end. On top of the wrap, we glued three, four-inch-long feathers. That arrow weighed 475.2 grains and zipped through a chronograph three feet in front of the bow at 257 fps.
Arrow No. 2 was tipped with a 100-grain field point, and a 7-inch-long decorative wrap was placed at the nock end. On top of the wrap, we glued three, two-inch long Blazer vanes. That arrow weighed 454.5 grains and flew out of the bow at 262 fps. Arrow No. 3 was tipped with a 100-grain field point, and three two-inch-long Blazer vanes were glued to the shaft. That arrow weighed 444.8 grains and flew at 264 fps.
Next, we backed up to shoot those same arrows at 20, 30 and 40 yards to see how they performed at those distances, which bowhunters commonly face in the deer woods. At 20 yards, Arrow No. 1 was timed at 247 fps, Arrow No. 2 at 254 fps and Arrow No. 3 at 258 fps.
The fact that the arrow carrying feathers instead of vanes lost the greatest amount of speed came as no surprise to Kaufhold.
"Those feathers will fold flat when the arrow comes off the bow," he said. "As that arrow loses velocity, those feathers stand up and that increases the drag, slowing it down even more."
To show how much our arrows dropped as they flew, we used our 20-yard sight pin to aim at targets 30 and 40 yards away, then measured the distance from the center of the bull's-eye to the impact point. Arrow No. 1 struck the 30-yard target 7.7 inches below the bull's-eye and hit 18 inches low at 40 yards. Arrow No. 2 struck the 30-yard target 5.25 inches below the bull's-eye and hit 15 inches low at 40 yards. Arrow No. 3 struck the 30-yard target 4.75 inches below the bull's-eye and hit 13 inches low at 40 yards.
Since IBO recommends bowhunters shoot arrows weighing no less than five grains per pound of draw weight, we set up a fourth arrow near that minimum to shoot under the exact same conditions as the other three arrows, just to gauge its speed and flight performance. We took a 27.25-inch-long Gold Tip Ultralight 400, fitted it with three two-inch-long Blazer vanes and tipped it with a 125-grain field point. Arrow No. 4 weighed 362.8 grains, slightly more than the 335-grain recommended minimum for our 67-pound bow.
The arrow left the bow at 289 fps, and, at 20 yards, was covering 281 fps. Using our 20-yard sight pin at 30 yards, the arrow struck the target three inches below the bull's-eye, and hit 10 inches low at 40 yards.
"Yes, that arrow is moving faster and performing better on the target," Kaufhold said. "But it's not going to have the same penetration as one of the heavier arrows. Because it's a lighter arrow, it's going to slow down faster on impact. It's still an arrow you could use on deer, but I'd go with something over 400 grains."
Put the pedal to the metal with your bowhunting setup this season and maybe, instead of watching that arrow sail underneath the belly of a deer, you'll see it zip right through the vitals.