[Redbarren]

What is the formula for let off percentage, anybody?

 

[GMorel1916]

From Hunter's Friend:

"To compute our percent let-off, all we need to know is the bow's peak weight and it's minimum weight (at full let-off). But when you measure the peak and minimum weight, you'll get slightly different numbers depending on if you're in the process of drawing the bow back or letting down. Here's an example. Let's say you draw the bow back and the peak weight is 60# and the minimum weight at full let-off is 15#. But when you measure while letting the bow down, the peak is only 52# and the minimum at let-off is 13#. If you compute the let-off using either set of figures (15/60 or 13/52) it's easy to compute that at full let-off you're holding back 25% of the peak weight. So this bow must be a 75% let-off bow, right? AH-HA!!!!! Finally!!! Here's where the technical snafu comes in.

Some manufacturers play a little trick when computing their let-off percentage. Instead of using the matching set of numbers, they choose the high figure from one test (drawing back) and the low figure from the other test (letting down). And if they use the 60 from one test compared to 13 from the other, the math comes out a little different. If we compute the let-off with 60 vs. 13, we get just over 78% let-off. And since let-off is usually listed in 5% increments, round-up and viola! 80% let-off! So in our example, the bow would have an advertised or "Effective" let-off of 80%, but it's "Actual" let-off would only be 75%. Tricky, eh? And of course, one could argue that the extra 5% really doesn't matter. But if that's the case, why fib about it in the first place?

So be aware. You may not be ACTUALLY getting as much let-off as you
think."

Greg

 

[Redbarren]

let off

GMorel1916,
Thanks for more than an equation, very insightful and helpful. Just what I needed to here. I didn't know that some manufactures do that but doesn't surprise me.