Penetration: shaft diameter vs. weight

[Bulzeye]

I need to select new hunting arrows soon.

What affects penetration more?
The kinetic energy of the arrow, its momentum, or shaft diameter?

I've heard a number of arguments:
Some say it's KE, the guys who like heavier shafts swear by momentum, and now I've heard shaft diameter affects it too.
Which is the most important aspect of an arrow's ability to penetrate?

[BobCo19-65]

Well, I'll only dare to answer one part of your question. I think most would agree that smaller diameter shafts (as long as the spine is correct for a particular setup) will penetrate better with all else kept equal.

[Q2XLScott]

I will have to say an heavy arrow. I know a lot of game is taken with lite arrows. But I like to have complete pass throughs. I have shot spitfires for five years and grim reapers last year. I have only had one arrow that did not pass completly through. That was a doe I shot almost straight down and spine shot her. I have proved that heavier penetrates better on my target. My 3-d setup is about 13fps faster than my hunting set up with my hunting arrow about 70 gr. more. My hunting arrow will shoot through the target. So for me the heavier the better.

[AllenRead]

More is better for momentum and KE. In the case of diameter, less is better.

I hunt with the old pultruded arrows that are 15/64" (0.243") diameter and get great penetration on deer and targets. In fact I quit shooting them at targets since they either penetrate and ruin the vanes or are very hard to pull out. On the same target matt (stacked celotex), they will penetrate at least twice as far as my 2613's.

On a bag target the pultruded arrows will go all the way through. The 2613's sometimes bounce off if I have my bow turned down a little.

Like BobCo19-65 said, all else being equal, thinner arrow will penetrate much better than fatter arrows.

Allen

[Bulzeye]

I was afraid of that.

So the lightest/fastest arrows of a given spine, which, if aluminum, will naturally be larger outside diameter and thinner walled, will therefore be poorer penetrators because of their larger diameter?

So this will be another one of those trade-offs, right?
I can go big to get flat trajectory, speed, and KE, but will still sacrifice pentration?
How does this work?

[thesource]

I'll agree that smaller diameter arrows penetrate better in targets, with target points.

I have never noticed much of a difference with broadheads on game. I used to hunt with 2413 XX75 arrows, and always had complete pass throughs. Now I use ICS carbon, smaller diameter arrows and still get pass throughs.

I believe broadhead design and draw weight have more to do with penetration than shaft diameter.

[Arthur P]

I think the idea of friction on the arrow shaft is somewhat overblown. Yes, I think it does play a role but, since most of the resistance is against the broadhead blades and since living flesh naturally pulls away from a cut, it's a minor role. I'd say there is far more resistance on plastic vanes going through a wound channel than there is on the shaft itself. Another good reason to use feathers instead.

So, I'm going to say weight is more important than shaft diameter. Now, if you take a small diameter arrow and add weight to it, then it would likely penetrate slightly better than a fatter arrow of equal weight. If that smaller diameter arrow is also a good quality carbon shaft, then you've got the best of all worlds.

[Swamp Dawg]

If that smaller diameter arrow is also a good quality carbon shaft, then you've got the best of all worlds.

Hmmmm, Maybe those new ACC Super Slims are worth a look.

[dsheally]

I believe weight/momentum has the most effect in penetration when it comes to
penetrating through animals. Shaft diameter to me is less of an issue unless you
are shooting into stacked cardboard or simular materials. The smaller diameter
shaft will almost always out penetrate larger diameter shafts with fieldpoints in
this type of target, much less resistance. In hunting situations, the shaft will follow
the path the broadhead has cut through the animal no matter what it's diameter
is. (i.e.-aluminum shafts). So to me shaft size is less of an issue when it comes to
penetrating through flesh. A straight flying arrow, a razor sharp broadhead, and
the momentum to go through the animal is what is important to me.

[dsheally]

And I agree with Arthur P, 100 %. Match the added weight/momentum with a small
diameter shaft and you would have one serious penetrating arrow on both flesh
and targets.