One thing that you’ll notice right away on a pack of 3-vane arrows is that there’s almost always one vane that’s colored differently from the others. This is actually important on modern arrows.
Why is one vane on an arrow a different color? The odd colored vane on an arrow is used to index the orientation of the arrow on the bow. The vane needs to avoid contacting the arrow rest in a way that will alter the arrow’s flight path or cause damage to the equipment.
This odd-colored vane is called an index vane or cock vane. For traditional arrows with feather fletching, you might also hear it referred to as the index feather or the cock feather.
Depending on the style of the bow and arrow rest, this vane could be placed in different positions. Most commonly, the difference in vane orientation depends on whether you’re shooting a compound bow or a traditional bow.
Which Way Does the Index Vane Go on a Compound Bow?
For a compound bow with a whisker biscuit, the index vane goes up.
You’ll notice on your whisker biscuit that there’s a section of the “whiskers” on the bottom that’s a different color than the rest.
This is because those whiskers are stiffer than the other ones. They take the brunt of the wear and tear since the arrow rests primarily on them. That’s why they need to be stiffer.
If a vane travels through these stiffer whiskers, there will be uneven forces across the vanes that will mess up the arrow’s trajectory.
With the indexing vane up, all three vanes will be positioned so that the pressure from the whisker biscuit is even on all sides, resulting in a reliable arrow flight.
One thing to note is that if you face your indexing vane down when using a whisker biscuit, one of your vanes is going to line up with the cutout where you drop in your arrows.
This will pretty well ensure a skewed flight path.
Basically, all three vanes will have uneven forces applied as they go through the biscuit. The bottom vane will be going through the stiffest whiskers, one of the upper vanes will go through the regular whiskers, and the last one will pass through the nearly open cutout.
For accurate shots, that can’t happen.
If you’re not using a whisker biscuit, your index vane will have a different position.
Another thing that you might see on a compound bow is a launcher-style arrow rest. These used to be the most common style, although they’re becoming less popular and more outdated.
A launcher-style arrow rest is usually just two prongs that hold up the arrow. They don’t automatically fold down, and they don’t fully enclose the arrow like a whisker biscuit does. This is probably why they’re not as common anymore. They’re the best of no worlds.
For a launcher-style of arrow rest, the index vane will point down instead of up.
Launcher-style arrow rests usually come as either a two-piece prong that supports the arrow or a single, thin single blade that contacts the shaft of the arrow in two places.
Which Way Does the Index Vane Go on a Traditional Bow?
Instead of pointing up, the index vane on a traditional bow typically points to the side, away from the bow.
So if you have a right handed bow, the index vane will generally point to the right, and vice versa for a left handed bow.
This is how it should look:
Which Way Does the Index Vane Go on a Crossbow?
A crossbow bolt’s orientation will generally depend on the number of fletches. Some bolts use two of four bolts, but many use three.
For three or four vane crossbow bolts, the index vane typically goes down into the rail. You should know right away if this is correct since there should be a channel that allows the bolt vane to pass through without interference.
When There Is No Index Vane
Some people, especially those that fletch their own arrows, might not use an index vane.
Generally, this is because they have an arrow rest that doesn’t require the arrow to be indexed.
A drop-down arrow rest literally drops away when the bow is fired, meaning that there is nothing remaining that could interfere with the arrow fletching as it shoots out of the bow.
Alternatively, a few very traditional archers prefer to use feather fletching and shoot with their thumb acting as the arrow rest. You’ll see these on very simple longbows and horse bows. These often don’t use an index vane.
One of the main reasons why they can get away with this is because feather vanes are much softer than rubber or plastic vanes. If the vane contacts something as it’s being launched, it will not affect the trajectory nearly as much as something more rigid.
All that said, most people have an index vane on their arrows whether they use it or not. This is how most arrows come when you buy them new anyway.
Why You Should Use an Index Vane Anyway
Even if your arrow rest doesn’t require the use of an index vane, it’s a good idea to use it anyway.
The reason for this is that you can dial in each arrow individually to help keep your groupings tight. Keeping the index vane in the same location means that you can identify if the arrow tends to pull to one side or spin inconsistently.
You can fine-tune all your arrows by adjusting your fletching. Basically, just remove the vane that you think is the culprit and reattach it until you’re happy with it.
One of the things that I like to pay attention to is if all my arrows are landing with the index vane in the same orientation.
For example, I’ll set up at 10 yards and launch 6 arrows, one after the other. Then, at the target, see if the index vanes are clocked consistently. If they’re all timed more or less the same, then I know that I’ll get a good shot regardless of which arrow I choose.