This is for you if you have never heard the term Kinetic Energy concerning bowhunting before. When going after game animals you need to know which compound bow is able to take them down properly. This depends on a few factors you simply should know before starting to hunt.
Kinetic Energy For Hunting
Is Kinetic Energy really the most important factor when it comes to bowhunting? The discussion around this question seems to be as old as bowhunting itself. A lot of bowhunters see it as a relic from the old days when game was hunted down with traditional bows and wooden arrows.
Back in the day they did not have the high-tech compound bows available like we have nowadays. So the question of Kinetic Energy as a factor for hunting is still an important question that keeps popping up all the time in forums and discussion groups. Because of that I decided to give you a brief overview of the topic that might affect your choice when it comes to buying a compound bow for hunting.
For calculating the Kinetic Energy for hunting you need to know the speed and the weight of your arrow. The formula to do it goes like this:
Kinetic Energy (KE) = Weight X Velocity Squared /2 X Acceleration of Gravity
So if you shoot 425 grain arrows with a speed of 310 fps the KE is calculated like this:
KE=[(425)(310²)]/450,240 KE= 40.842.500/450.240
KE = 90.71 ft-lbs
As you can clearly see Kinetic Energy depends on the speed of your arrows. This speed, on the other hand, depends on the poundage of the compound bow and the weight of the chosen arrows. A simple relation between speed and weight is the following: As arrow mass increases, its speed decreases. It’s as simple as that. But the power of a compound bow, by the way, is transfered more efficiently into a heavier arrow than into a light one which is quite interesting. Therefore heavier ones produce a deeper penetration because of the higher Kinetic Energy that can be achieved with them. So for bowhunting, heavier ones seem to be quite handy.
What Is The Best Arrow Weight For Hunting
If you asked what is the best arrow weight for hunting I would answer as I would most of the times concerning questions about something that is best – that there is no one best arrow. The discussion nowadays about using lighter ones for accuracy or heavieones for better penetration seems to be going on forever and choices are often made based on experience and advice of seasoned bowhunters. There are pros and cons for both.
Lighter arrows will fly more quickly resulting in holding their trajectory better. So simply said they fly more straight, which makes it easier to shoot at longer distances, thus making them more forgiving concerning distance estimation. A disadvantage of lighter ones is that they will produce more noise when shot. So you will need to compensate that with silencers or stabilizers, because sound travels faster than an arrow so the game animals might get warned.
Heavier arrows will result in more knock-down power and deeper penetration. On the other hand they tend to nosedive more quickly so you need to be good at estimating distances. A lot of bowhunters still prefer heavier ones (400-425 grains). So it will be a lot harder to hit your target at longer distances (think 30 yards + ).
The argument against Kinetic Energy is that most of the available high-tech compounds will have enough power anyway and that you can take down a deer even with a 30 pound bow if you hit it in the right spot. Which pushes the responsibility of hunting in a humane way back to you and your skills of shooting. Because even a 60 pound compound won’t be able to penetrate the shoulder of a whitetail to get to the vital organs in every situation – instead a well placed hit of a lighter bow will.
The decision to go with higher Kinetic Energy or faster arrows for hunting will also depend on the game you are after. Simply said: Small game is doable with lighter ones, large game requires heavier ones.
Just look at Easton’s field chart to get an idea what Kinetic Energy is recommended for what type of game.
When buying a modern up-to-date compound bow you will find speed ratings (mostly by the IBO; International Bowhunting Organization) for all the available models on the boxes. These ratings assume some standard values like a draw weight of 70 lbs, a draw length of 30″ and an arrow weight of 350 grains, so take’em with a grain of salt. Because as soon as you change just one factor it will affect the speed and therefore the Kinetic Energy immediately.
For example 70 lbs is a hell of a lot to draw. Many bowhunters adjust the poundage down to 60 lbs. A lot use heavier arrows than 350 grain, often 400-425 grains for a higher impact. Some have a smaller draw length etc. etc. All these changes result in a lower KE. So don’t forget that when choosing a compound bow for hunting.
What affects the Kinetic Energy as well are weather conditions, being in the field and, of course, the travelling length of your arrow. Expect to subtract 1.7 ft-lbs of KE for every 10 yards traveled.
How Much Kinetic Energy For Starting Out With Bowhunting
So if you still are unsure about what is good kinetic energy for a hunting bow I would recommend – for starting out in bowhunting – to go for a compound that has a draw weight of 60 lbs (maybe get one that is adjustable like the Infinite Edge Pro by Diamond Archery, so you can experiment with different poundages later when you have gained experience) together with arrows that weigh around 400-425 grains (to choose the right arrows for you read our guide here => Choosing the Right Arrows).
Over time you will find a good compromise between accuracy and knock-down power that works for you. But for starting out in bowhunting the recommendations above are quite good. Just don’t forget that KE won’t matter if you don’t hit the vital organs. So shooting well is the most important factor when going hunting.
Coming back to the question if Kinetic Energy is the most important factor when choosing a compound bow for hunting:
The answer still seems to be rather subjective. For me a very important point is to be able to hunt in a humane way. So I certainly would go for heavier arrows and a compound bow with at least 60 lbs. And as I know that these will only come into play like they should if I hit vital organs I will concentrate on my shooting skills rather than to rely on the power of my bow alone.
I hope I was able to shed some light on the topic of Kinetic Energy for hunting and that you got something out of it as well.
Thanks for reading and shoot straight!