The Lure Of The Light Draw Bow: A New Direction In Traditional Archery
Paperback Book by Peter Laffin
This collection of essays is focused on the relationship between draw weight, speed and efficiency in traditional bows and their impact on the experience of being an archer. It also explores the role of belief systems, or paradigms in limiting creative design. It looks at alternatives to technology when solving problems of traditional bow physics. It is an adventure into a new point of view.
Measuring a Bow’s Hunt-Ability
(Excerpted from The Lure Of The Light Draw Bow)
Three men walk into an Archery shop. The first man says, “ I want to go hunting with a bow and I know that I can pull 60# to full draw.” The second man says, “I want to go hunting with a bow, what would you recommend?” The third mans says, “I want to go hunting with a bow that’s comfortable to shoot.”
The first man walks out with a 60# bow. The second man walks out with a 50# bow. The third man walks out with a 35# bow. All three men are successful hunting that fall and all three men had complete pass through shots on deer. What does that say about using a bow’s draw weight as a criterion for measuring a bow’s hunt-ability?
In the general archery community there are certain ideas and beliefs that have become so common that they are accepted as fact. Examples of some of those ideas and beliefs are; you need a minimum of a 45# bow to hunt large game (as in deer, elk, etc), more draw weight = more power = more arrow velocity, more=bigger = better, you need heavy arrows with high FOC (forward of center balance point of the arrow), high tech materials and techniques are superior, you need to have the latest innovations or you’re actually under equipped. And there are more and more and more beliefs.
People have been hunting with bows and arrows successfully for over 10,000 years. For some of those 10,000 years they didn’t have carbon fibers in their interchangeable bow limbs and yet they were successful.
What does a bow, and a bow in combination with an arrow, actually have to do to have Hunt-Ability? It has to launch an arrow of sufficient weight and speed to penetrate an animal to the point of disrupting its vital functions. Now the question becomes what is sufficient weight and speed? In real life that is gleaned from actual experience. It probably became evident early on that some bows shot arrows faster than other bows and that was a good thing. Hence a centuries long endeavor to design and build faster bows. It probably also became evident that heavier arrows, if they could be launched fast enough, were more effective than very light arrows on larger game.
Today we have the luxury of a wide array of archery equipment design and development. Many people are actually a little lost in the wide array. They don’t have sufficient actual experience to know what is required to hunt with a bow and arrow. So they rely on what others tell them, what they can find through research from magazine articles and the internet, what their friends say and what the people at the archery shop advise. Most of their ideas and decisions come from sources outside themselves. They do their best to discern the information available and then they choose a perspective and go with it. This is how a consensus is formed, it is fortified by agreement with and of others, and soon becomes accepted as the way it is. This is how we got to the belief about a minimum of a 45# bow for hunting large game etc.
Just for a change of pace let’s look at what is actually required to hunt deer. A well placed shot on a deer will be through the rib cage and into the lungs and sometimes the heart. What does that arrow have to do? It has to penetrate about 1/8” of soft skin, then go through about ½” of muscle and then it’s into the lungs and maybe the heart. If it has enough momentum it will pass through the lungs, go through the ½” of muscle on the other side, then the 1/8” of soft skin and then fly off into the great unknown (and maybe stick in a tree if you’re lucky). Of course it could hit ribs. If it’s a two blade broadhead it will probably twist as it contacts the ribs with one side sliding up and the other side sliding down to pass between the ribs as it passes through. How much power does it take to do that?
Maybe there is a place in history that can help with that. Arthur Young and Saxton Pope were two avid archery hunters in the early 1900’s. So avid in fact that they started what is now the standard for measuring big game trophies shot with a bow. It’s called The Pope and Young Club. It is the archery equivalent of The Boone and Crocket Club. Pope and Young hunted all North American game with archery equipment, including bear, mountain lion, moose and elk. Saxton Pope wrote a book, Hunting with the Bow and Arrow. In this book he describes hunting at a scale few, if any of us, will ever attain. They have a huge quantity of hunting experiences to draw on. At one point Art Young stated that you could shoot any game on the North American continent with a 50# bow. In those days there were no fiberglass laminated bows, no compound bows, no bows with carbon fibers in their limbs. The bows they were using were bows they made themselves from single pieces of yew or osage orange wood. A good wood bow in those days (and still true today) will shoot a 500 grain arrow 150 feet per second. So, what Arthur Young was saying was that you could shoot any animal on the North American continent with a 500 grain arrow traveling 150 fps. That seems like a good place to start for testing the Hunt-Ability of a bow.
How heavy a draw weight must a bow be to shoot a 500 grain arrow 150 feet per second (fps)? Wait a minute. Who says arrow speed is dependent on a bow’s draw weight?
Draw weight measures draw weight. It does not measure speed. A chronograph measures speed. There is beginning to be an awareness that not all bows are created equal. Some bows are more efficient. Bow efficiency is measured with a chronograph. The higher the arrow speed, the more efficient the bow.
It was realized that an industry standard had to be adopted if bow speed comparisons were going to be apples to apples. A formula of arrow weight to bow draw weight was adopted, the thought being that what would be measured was a particular amount of weight of arrow for every increment of bow draw weight. Nine grains of arrow weight for every one pound of bow draw weight was agreed upon. Today that is the formula used for measuring arrow speed in traditional bows. Compound bows use the formula of 5 grains of arrow weight for every pound of bow draw weight, which helps explain the velocity differences between the two types of bows. Lighter arrows go faster.
Efficient bows produce higher arrow velocities. It is not uncommon for one 50# draw weight bow to shoot a 450 grain arrow (9 grains per pound of draw weight… 50# x 9gr = 450 gr arrow) at a speed of 165 feet per second (fps) and another 50# draw weight bow to shoot the exact same arrow 185 fps. The 20 fps difference is due to one bow being considerably more efficient.
A more accurate way of judging a bow’s performance could be the arrow velocity that it produces. A more efficient bow translates more of your muscle energy into arrow speed than an inefficient bow, which uses more of your muscle energy just to move its limbs than is optimal.
Here is a chart of how many view arrow speed relative to a bow’s performance:
Arrow Speed Rating aka ASR
Acceptable standard arrow speed of 165 fps (112.5 mph) could be considered “normal”
Arrow speed of 170fps (115.9 mph) considered “good”
Arrow speed of 175fps (119.3 mph) starting to be considered “quick”
Arrow speed of 180fps (122.7 mph) considered to be “fast”
Arrow speed of 185fps (126.1 mph) considered to be “incredibly fast”
Arrow speed of 190fps (129.5 mph) considered to be “nearly unattainable”
Arrow speed of 195fps (132.9 mph) demands you “check your chronograph”
Arrow speed in the 200fps (136.3 mph) considered to be “impossible”
Some bowyers are now putting the ASR on their bow’s limb along with the draw weight to help communicate more accurately how effective the bow is.
There are a few bowyers who are focused on designing and building super efficient bows. Some of these bowyers are shooting a 500 grain arrow in excess of 150 fps out of 30# bows (those same bows are shooting standard 9gpp arrows 195fps).
That flies in the face of the general archery world’s belief system of what it takes in a bow to hunt large game…remember one of the earlier stated beliefs is that it requires a 45# bow minimum to hunt large game.
It is becoming apparent to those bowhunters who are harvesting game and investigating the actual performance of arrows in the field that arrows weighing 400 – 500 grains are a good range for hunting deer and other large game. As this, and the difference in bow efficiency becomes more widely recognized we may see bowyers not only stating the ASR on their bows, but also how fast that bow shoots a 500 grain arrow. That is what the archer really needs to know.
The bottom line here could be stated that a bow’s Hunt-Ability can be determined by how fast it will shoot a 500 grain arrow. That takes it out of the realm of opinion and theory and puts it in the realm of specific performance. Of course one might want to verify that Art Young is qualified to make the statement he did.
As one’s attention turns in the direction of bow efficiency it becomes apparent that there are bows of much lighter draw weight that produce better results than some common bows of much heavier draw weight. Now a new option presents itself. An archer can have a bow that is easier to draw that will perform as well or better than a bow of say, 10# -20# heavier draw weight. No longer does a bow hunter have to buy a bow that is at or near his limit to pull to full draw. A bow that is a challenge to draw will not be conducive to practice sessions of 50 – 100 arrows per session. Muscle fatigue will not permit it. A bow that is easy to shoot will allow unlimited practice sessions and will not induce fatigue. An archer who can shoot more will enjoy it more and will become a better archer in the process. A better archer will be a more successful hunter. If an archer has only one bow, and uses it for everything, hunting, 3D competition, stump shooting, target practice and aerial shooting he or she will become much more proficient with their one, go to, favorite bow.
The Hunt-Ability of a bow is most dramatically affected by its efficiency. Find an efficient bow and find a friend. An efficient bow is likely to become a welcome companion in your archery world.