What Is Arrow Spine and How Do I Know What Is The Right Spine For My Bow?
Monday, April 20, 2015
Spine is the amount of stiffness in the arrow's shaft as it flexes when it leaves the bow. This is called the dynamic spine. To achieve good patterns the spine should be consistent throughout all of your arrows. An arrow that is too weak of spine could break upon firing from the increased strain being placed upon it. Stiffer arrows aren't as critical, but will not give you ideal patterning. So, it would be much better to have an arrow that was too stiff versus too weak.
Inconsistent spines can create lots of lefts and rights when you are patterning which is why it is very important to number your arrows and shoot them in the same order every time. I have my arrows numbered with either electrician's wire numbers or I write on the shaft with a marker. I have archers that number their arrows by writing on the index vane. However you do it is fine. What you are looking for is patterns for each arrow. As an example: my number 4 arrow consistently patterns low. So, I need to turn my nock to see if I can compensate for the spine.
As arrows get older—their spine can and will start to break down. So, if you are like me, and shoot indoor spots after years and years of shooting the same arrows we can expect to see some inconsistencies in arrows over time. A pro shop will be able to figure out what the correct spine would be for your bow setup. They will consider your draw length, draw weight, tip weight and what type of bow you are shooting. Be sure to inform the staff what you will be doing with the arrows. Hunting for large game would require an arrow that would give you the best kinetic energy and penetration possible while shooting indoor spots would require something totally different.
One more tip... if you change your draw weight you may have to change your arrows to a more rigid spine too. Keep this in mind especially if you are just getting into archery and as you get stronger drawing your bow back.