I've killed several deer bowhunting because I understand how to compensate for the angle when shooting up- or downhill. I've also seen a few deer that died because the bowhunter didn't understand range compensation, but managed to find a vital area anyway. You can't beat luck, but for those who would prefer to rely on a skill set, read on.
Whether shooting a bow or a gun, the physics are the same. The formula for determining the horizontal distance vs. the line-of-sight distance is COS (degree of slope) • line of sight distance = horizontal distance. To put this into a few numbers, let's assume you are shooting at a target 60 yards away at a 20-degree slope (up or down). The formula would be COS (20) • 60 = 56.4 yards as a sight setting. I know what you're thinking, and yes, I am just going to hit the button on a laser rangefinder with a built-in compensation--
1. Throw out formula
2. Depress button
3. Violà arrow hits deer. If life were only that simple.
The reason that horizontal distances work over line of sight is simple: gravity. While this concept may be easy for most to understand, far too many stop at this point, then miss the shot. Shooting up- and down-angle shots requires an adjustment to your form accordingly. To understand this, we will need to dig into a couple more shooting concepts.
Shooting Form
Let's suppose you are shooting from an elevated treestand. The buck is 20 yards from the base of the tree, and your stand is elevated 18 feet. The compensation at this range is not going to make a huge difference either way. In an effort to minimize movement, you point your bow at the deer and draw. This works if you think of your body, at full draw, as the shape of a capital letter "T." More correct, think of your upper body as the shape of a capital letter "T." Bend at the hip, and maintain the T-shape of your upper body. This prevents your anchor point from floating and ruining an otherwise good shot.
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