Why do we shoot higher than normal when shooting downhill

[Matagorda]

I've been practicing from a treestand and my first group of 3 arrows tend to always be high.  What is the cause of this? Alternatively, when I shoot from below my tank dam up to a target, it tends to be low. 

What are the physics of this?  I've heard others mention this as well. 

[MGH]

I learned this compensation shooting 3D way back when I shot compounds.  It does depend on the angle, either up or down.  It has to do with the affects of gravity on the arrow being less at extreme angles.  This depends on how high you stand is hung and how far the intended target is from the tree.  Think Trigonometry.....

[bowmaster12]

Its usually  a result in a break of form.  When shooting from an elevated position you have to keep everything the same.  By bending at the waist to keep arms and shoulders aligned.  Typically we tend to be lazy and drop our bow arm to bring the sight picture "on target" doing this changes all of our alignment and we shoot high even though the sight picture was correct. There is math aswell but for the distance most of us shoot at and the height we go in trees i think its pretty minimal and it is more to do with not bending at the waist.

[BAK]

It would seem to me to be a factor of the angle changing the horizontal distance gravity acts on the arrow.

[Crooked Stic]

If you don't bend at the waist and just lowering your bow arm them you have increased your draw length and gain more fps.

[Orion]

As already noted, gravity (very slight effect) and not bending at the waist (more substantial effect) are the culprits for most of us.  On critters, I think it also has to do with what we pick out to aim at.  Most of us tend to aim for center body height.  That's through the lungs on a horizontal shot.  It's in the back on a shot from above, or the underside when shot from below. Need to consciously aim at the bottom 1/3 of the critter when shooting from above, or raise our aim when shooting from below. 

[durp]

Try this...stand straight and draw ur bow now lower ur bow arm and ull see real fast why u shoot high...now draw again then bend at the waste and keep ur form the same...it's a form thing not gravity 😉

[McDave]

I think you can see from the replies so far, the “physics” are complex, and subject to different interpretations.  I recommend that you shoot with good shooting form, i.e. maintaining the magic T by bending/leaning at the waist so your shoulders are in line with the arrow.  It can help to keep balanced, when the downward angle is high, to move your hips backwards as you lean forwards.  Then practice taking the shots you expect to encounter while you are hunting.  If you shoot with good form and your arrows impact high, as they do for me too, then aim lower.

[Bowguy67]

Bend at the waist. That simple. Try something. Take a string and draw it as you would a bow to anchors. Stay anchored but lower your arm to shoot without bending at the waist. I bet more string pulls out.

[Bowguy67]

Need to consciously aim at the bottom 1/3 of the critter when shooting from above, or raise our aim when shooting from below.

Orion I’m sorry but either you mixed this up accidentally or you’re wrong. Animals vitals sit inside as an apple say in a wine barrel. Say it was exactly center of that barrel. By your explanation you’d aim for the bottom 1/3 of the barrel. Apple is 1/2 way up. You’re way under missing the vitals.Even if the apple was only a 1/3 up the barrel you’d still miss as youd pass through before hitting the apple. You’d need to aim/pass through high on entry. Same for animals, aim for the apple in the center so we angle through correct area.I’m suspecting it was only a misprint though. Always aim for the center, not the face of the target. Animals have depth we gotta consider that.

[Orion]

Bow Guy.  Yes, shooting for the center of the target/body is the goal.  However, when we're above the animal at a fairly steep angle, the center of the mass (we see) is closer to the animal's back than its side. Let's say a deer is standing broadside at 15 yards.  From the same level, we can see his ridge line and his belly line. Lets say the distance between the two lines is about 18 inches.  A shot to the center, between those two lines, 9 inches up from the belly line, should hit the center of the lungs. 

Now, get 15 feet or higher above the animal.  We can no longer see the belly line because the animal's body curves inward toward the belly, beginning 4 to 6 inches above the belly.  Thus, the lowest part of the animal (that we can now see) is 4 to 6 inches up the body.  At the same time, now we can see to the other side of the animal's back line, say 4 to 6 inches further off the opposite side of the critter's spine. The distance between the two visual lines is still 18 inches, but if we shoot the center of the mass (we can see now), the arrow will impact high, about 13 to 15 inches above the belly line, and it's likely to take out only the offside lung. Actually the distance between the two lines shrinks the higher one is above the animal. 

"Shoot at the lower third of the body" is not the visual image I wanted to convey.  Poorly phrased. What I was trying to say is aim a third of the way up the mass (that we see) from above.  That should place the arrow center body.  And even if we end up shooting a little high because we don't bend at the waist, we should still get both lungs.  Hope that makes sense.   

This is particularly important the higher and closer the hunter is to the animal.  The farther away the animal is and the lower the hunter is, the less the need for aiming lower than the center on the body mass (that we can see). When the hunter is on the same level as the critter, the aim is again at the center of the body/mass, unless the shooter is going for a heart shot.

I hope the parenthesis weren't distracting. Can't bold or underline so I used them for emphasis.