At our recent club shoot (Briar Rose Field Archers) in July, we made the decision that we wanted to run speed checks on compound bows and crossbows, so we set up the club chrono.
For those of you unfamiliar with a chrono, it measures the speed of an arrow and under the NFAS the maximum speed allowed is 300 FPS (feet per second) as per the shooting rules. There is a 3% allowance for variance in chronograph equipment being used. This means a bow reading 309 FPS is still legal.
The chrono has a sensor at either end between metal V rods that are used to offer a guide to the archer as to where to shoot. The archer shoots over the top of the chrono, crossing the 2 sensors between the two V with their arrows. The archers shoot a few feet from the chrono into a boss as shown in the picture below, where you can see the chrono mounted on a tripod and the target boss beyond. It’s important that the chrono is set up level and there is sufficient light for the sensors to register the arrow passing above.
Anyone over the speed limit would be asked to slow the bow down or not be allowed to shoot.
There were a few interesting observations
- All compounds and crossbows we tested were legal i.e. speed less than 300 fps.
- The reaction and feedback from the attending archers were very positive, not just from those who were shooting compound or crossbows, but traditional archers shooting recurves or longbows. These were curious to see what speed their bows were producing.
- It generated lots of discussion with some about how they might increase their speed. How the weight of arrows affects speed. How shooting light arrows increases speed but can damage bows and so on.
- Several had never seen or were even aware of what a chrono is or why it’s important. Possible because they were shooting styles other than compound or crossbow.
The latter point is worth revisiting as unless you frequent national championships or 3Ds it’s unlikely you will have encountered one. Few clubs have them or if they do I haven’t seen them often at shoots. This raises the question of whether there are bows out there being shot that are exceeding the speed limits through no fault of the archers.
For those interested you can see the results of the Briar Rose shoot on the club website. Also wanted to say a special thanks to Rich Clarke who manned the chrono. You might know Rich from Archery Geek outdoors Podcasts.
Anyway, thanks for reading.