The spine of an arrow measures how stiff that arrow will be. There is no straight forward answer as to what spine of arrow you will need to shoot, as this will depend on a lot of different things.
But, it is good to know that, generally speaking, the lower the number of the arrow spine, the stiffer the arrow will be. But, how do you know what spine to use?
In terms of spine stiffness, you should use a lower number of spine as the draw weight of the bow and arrow increases. There are a number of charts that you can use to calculate this, but generally it is accepted that you should work down the stiffness chart as you work up the draw weight chart.
The draw weight of the arrow will be directly impacted by the length of the arrow. If you are using a longer broad head arrow, then you should also choose a stiffer arrow, in order to ensure that you get adequate reach. If you do not have an appropriate level of stiffness, then your arrow will struggle to reach when put under the pressure of the draw weight.
So, to calculate the spine of the arrow that you need, you need to consider the length of your broad head and the draw weight of the arrow.
What happens if my Arrow Spine is too stiff?
You might be wondering what will happen if the arrow spine is too stiff. In short, if you use an arrow that is too stiff, then the arrow will not be able to do its job properly. Although arrows look like they have a very simple design, there is a lot of thought that goes into this, and a lot of technology that requires certain criteria for it to operate correctly.
One of the main criteria that an arrow needs to be correct, in order for it to work in the way that it is supposed to, is the correct arrow spine for the draw weight. This is very important because if these two pieces of criteria are not compatible with one another, the arrow will not be able to correct itself when it is in the air, meaning that it probably will not hit your desired target.
If the arrow spine is too stiff for the job, then the arrow will not be able to correct any errors while it is in flight. This will likely result in the arrow completely missing its target. The same sort of thing will happen if you use an arrow that isn’t stiff enough for the job.
This is why it is so important that you use the appropriate arrow spine, otherwise your arrow could quickly become unpredictable and difficult to control.
How do you Check Arrow Spine?
If you are relatively new to shooting a bow, then you might not be fully clued-up with all the jargon that comes along with it. One of the things that you may not know is how to tell what stiffness the arrow is. As we have said, arrow spines are all given a number. These numbers then go from highest to lowest, with the lower the number the stiffer the spine.
All manufacturers will label their arrows differently in terms of spine. Every manufacturer will provide a number for the different measurements, but these numbers might be found in different areas of the arrow depending on the manufacturer that produced the arrow.
In most cases, the manufacturer will state the spine measurement of the arrow on the arrow’s label, which can be found on the main body of the arrow. On this label, you will find lots of information about the arrow, so ensure that you look for the ‘spine’ measurement.
There are lots of different spine measurements that an arrow might be given, but some of the most common are ‘350’, ‘400’, ‘500’, and ‘600’. In this scenario, the ‘350’ arrow will be the stiffest.
So, if you want to check the arrow spine of your arrow, take a look at the arrow label to find the measurement.
What affects Arrow Spine?
As we said earlier, there are lots of different things that affect the arrow spine. Depending on different factors, you might need to use a different measurement of arrow spine. So, let’s take a look at what the main criteria that might affect arrow spine are.
Let’s start with the one piece of criteria that will affect the arrow spine, which we mentioned earlier, and that is to draw weight. Like we have said, if you are using an arrow which has a high level of draw weight, then you should also use an arrow which has a high level of stiffness. So, an arrow with a low spine rating.
But, this isn’t the only thing that will affect the rating of the arrow spine that you should use. Something else that will impact this is the length of the arrow.
Generally speaking, the longer the arrow that you use, the lower the spine rating (stiffer the arrow) you should use. The same principle works in reverse, so if you have an arrow that is shorter, you should use a higher spine rating so that the arrow will be less stiff.
So, the main things that will affect the spine rating of an arrow that you should use are the length of the arrow and the down weight that that arrow will experience in flight. Once you have this information, you can calculate the correct spine of the arrow to use in order to hit your target.
How do you stiffen an Arrow Spine?
If you find that your arrows are weaker than you require, then you might be trying to figure out how you can stiffen your arrow’s spine. Of course, you could always buy new arrows which have a stiffer spine rating.
But, this isn’t always possible. So, if you are hoping to stiffen your arrow’s spine, without having to buy new arrows, this is what you need to do.
Arrows are generally quite stiff in nature due to their design. Arrows with a stiffer spine will have less weight placed at the front of the arrow to ensure that there is a lot of force to combat the down weight that this stiffness of arrow usually experiences. So, if you want to stiffen an arrow, you should remove weight to the front of it.
Alternatively, you could also stiffen your arrow spine by adding weight from the rear of the arrow. This has the same effect as removing weight from the front, as it will weigh down the rear of the arrow, causing it to become stiffer. If this doesn’t work for you, you can also create stiffer arrows by cutting your arrows shorter to create a shorter length and a stiffer spine.
So, if you want stiffer arrows, but don’t want to buy new ones, there are lots of ways that you can adapt your arrows to make them stiffer.
What happens if your Arrows are too Tightly or Heavily Spined for your Bow?
As we have said, it is very important that the arrows that you use are perfect for the target that you are aiming to hit. If the arrows are not suitable, then your shots might come off target. So, let’s take a more specific look at what happens if your arrows are too tightly or heavily spined for your bow.
Both ‘tightly’ and ‘heavily’ spined arrows will experience the same issues while they are in the air. Arrows might look like they have a simple design, but there are specific arrows which are better suited for certain shots.
If you have a longer arrow, or a higher level of down weight, then the spine of your arrow has to be pretty stiff. But, if it is too stiff, you will experience issues.
If the arrow that you shoot has a spine which is too stiff for the job, then the arrow will not bend when it is in the air. It is very important that arrows are able to do this because the bending action will correct the shot, ensuring it hits its target. If the arrow is too stiff, it will not be able to correct the line of direction, meaning that the arrow will not hit its target.
So, if you use an arrow that is too tight or too heavy for the job, you will likely miss your target as the arrow will be working against you, rather than with you.