I was wondering what the equivalent poundage of a bow pulling 50# at 31" is to one pulling 28", assuming they are shooting the same arrow.

My Hill measures 45#@29", I pull it to 31" (50#).

If my brother, who draws 28", wanted to shoot the same weight arrow as I do, at the same speed as I do, out of a Hill, what poundage would he need?

I find it varies from bow to bow at least on the one I have owned. Most are 2-3# per inch.LCH

A rough way to calculate it is to divide the poundage at full draw by the number of inches you draw the bow.  So if your brace height is 7", you are drawing the bow 24" to get to 31". 50# / 24" = approx 2# per inch of draw.  So the poundage at 28" should be about 44#. This works pretty well as long as the bow is not stacking.

EDIT:  Woops, bad math...

Linear relationship, probably around 41# @ 28".  That's not considering stacking, though.

MCDAVE is right at least thats what i was told

between 41 and 44 somewhere would be my guess.go to your local bowshop and use a draw length arrow while pulling it down on scale to 28...read scale..theres your answer.

Dan Quillian used to say that an extra inch in draw length = an extra 10 pounds of draw weight in performance.  You can't equate poundage to fps...Van

Roughly 5% per inch

Original post modified.

I would say about 56 or 57lbs. at 28" to get what your getting at 50lbs. at 31"

missed that one word.equivalent

He will have to pull more than 50# to get the same arrow speed you have, because you have a longer power stroke.  How much more, I couldn't tell you.  54-55#?

He won't be shooting exactly the same arrow, because he will want to shoot a shorter arrow to match his 28" draw length.  The shorter arrow would have to be tuned for his bow, which might require a weaker or stiffer spine, since things are changing in both directions.  But it can still be a 650 grain arrow.

Yes, equivalent. Thank you.

McDave, that's what I was thinking.

I'll stick with 56 t0 58 lbs.

So basically, a 42#@28" Hill will perform like a 56# Hill when drawn to 31", right?  Interesting. Very Interesting.

Would a 55#@ 28" drawn to 31" perform like a 70#@ 28"?

I would guess that a 55# @ 28 drawn to 31" would have better performance than a 70# @ 28" drawn to 28".  Much better.  According to Dan Quillian.  I personally don't know because I have no way to test...Van

I might have to round up a chronograph.

Approx 25#'s to even things out between the 2 draw lengths provided your with recomendes Hill bow lengths, ie: 72" bow for 31" draw 68" bow for 28" draw.

QuoteOriginally posted by looper:
I was wondering what the equivalent poundage of a bow pulling 50# at 31" is to one pulling 28", assuming they are shooting the same arrow.

My Hill measures 45#@29", I pull it to 31" (50#).

If my brother, who draws 28", wanted to shoot the same weight arrow as I do, at the same speed as I do, out of a Hill, what poundage would he need?

you can add 3# per inch of extra drawlenght to get the same arrow speed from 28 to 31".
So to get the 50# @ 31" amount of "work" (KE) you will need very close of 59# @ 28".
BUT you can probably add close to 1# more to compensate de difference in dynamic bow efficency value: if you shoot 600 gr arrow with your HHILL 50# @ 31" that means 12 grain per pound arrow for you.
If your mate is shooting that 600 gr arrow with his 59# @ 28" that means a 10.17 gpp.
Bow dynamic efficency will grow with the arrow weight for all type of bows, and particularly in D shape bows. So the bow dynamic efficiency is better @ 12 gpp compared to the one @ 10 gpp. And close to 1# is a correct value here.(for the same bow design)

Indeed your brother should shoot probably very close to 60# @ 28" with the same arrow weight to get the speed you get with 50# @ 31". (assuming the same release quality for both archer...)