Bare Shaft Accuracy Testing
Now that you have the nocking point installed properly, the right brace height determined, and your arrows centered, we need to take a look at how your arrows are flying and how they hit the target to determine if further tuning is necessary, and if you should get different arrows for optimal performance with your setup.
To do that, you will need a few fletched arrows, as well as few bare shafts – the arrows without the fletchings. You can get some cheap bare shafts online, or you can just get regular arrows and remove the fletchings manually, thereby making yourself a bare shaft.
This is the first thing we’ll be looking for. Porpoising happens when the arrow alternates between rising and “submerging” relative to its intended flight path.
It’s called “porpoising” because the arrow behaves mid-flight almost like a porpoise (a mammal from the dolphin/whale family) does in water. If your arrow behaves as shown on the image above, this means that the location of your nocking point needs adjusting. Here is how to carry out the bare shaft test to solve this issue.
Step one: place a target 20 yards away and, aiming for a certain location, shoot two or three fletched arrows.
Step two: standing at the exact same distance from your target and aiming for exactly the same location as before, shoot two or three unfletched (bare shaft) arrows.
Now approach the target and take note of where your arrows landed exactly. There are two things to consider:
- If the bare shafts landed higher than the fletched arrows on the target, this means your nocking point is installedtoo low on the string. You will need to move the nocking point a little higher (start with 1/8″), and then repeat the two-step bare shaft test described above. Keep adjusting the height of your nocking point and testing until both your fletched and un-fletched arrows land at exactly the same height on the target.
- If the bare shafts landed lower than the fletched arrows, then the nocking point is positioned too high, and you will need to move it down the bowstring until both your fletched and un-fletched arrows land at exactly the same height on the target.
For this test to work, it is imperative that you always aim for the exact same spot when shooting the fletched arrows and the bare shafts; that you stand at precisely the same distance from your target each time you shoot; and that you use the exact same draw/aim/release technique.
The goal is to make sure both the fletched arrows and the bare shafts (unfletched arrows) land at exactly the same horizontal plane.
Important Note: at this point, you do not need to worry about both your fletched arrows and bare shafts landing right next to each other. You simply want both of them to land in the same horizontal plane, as this will mean you have successfully tuned your bow to avoid porpoising. For both fletched and unfletched arrows to land right next to each other, however, you also need to make sure that they are not fishtailing.
Fishtailing is kind of the opposite of porpoising, where rather than the arrow dipping up and down mid-flight, it will turn right and left. The image below illustrates this (pay attention to image caption):
To diagnose and fix fishtailing, do the following:
Step one: as before, place a target 20 yards away, aim for a specific location and shoot two or three fletched arrows.
Step two: using the exact same distance and aiming for the exact same spot on the target, shoot two or three unfletched (bare shaft) arrows.
Approach the target and take a look at where your arrows landed.
#1: If bare shafts hit the target noticeably to the left of the fletched arrows, it means your arrows have a stiff spine. Do one of the following, depending on your options:
- Reduce the tension on the plunger spring or move the rest assembly closer to the riser, thereby re-centering your arrows and moving the arrow points closer to the string.
- If your do not have a plunger or a rest assembly, you can address the issue by using heavier arrow points than what you are using. Say if yours are 100 grain, you can try 125 grain.
- Try increasing the brace height a little and see if that helps.
- If none of the above options seem to help, it likely means that you need to get arrow shafts with less spine/stiffness than your current ones.
#2: If your bare shafts hit the target noticeably to the right of where the fletched arrows impacted, it means your arrows have a weak spine. Do the reverse of what you did above:
- Increase the tension on the plunger or move the rest assembly further from the riser so as to re-center your arrows and move the arrow points further away from the string.
- If the above is not possible, get slightly lighter arrow tips and see if that helps.
- See if decreasing the brace height of your bow by 1/8″ – 2/8″ will help.
- If none of the above tweaks help despite your efforts, it means that you must get new arrow shafts with more spine/stiffness than what you have right now.
For left-hand bow, everything will be reversed; unfletched arrows landing too far to the left will indicate weak arrow spines, while unfletched arrows landing too far to the right will indicate a stiff spine.