Adding water to lower ABV and IBU?

[Angell]

I want to split a 10 gallon batch of a west coast IPA. One big, and one small. One boil. Don't want to set up 2 boil kettles.

The recipe is a big IIPA like a Pliney the Elder or Sticky Hands. After the boil, one fermenter gets 6 gallons of 1.080ish og wort and another fermenter gets 4 gallons of the same 1.080 PLUS 2 gallons of boiled cooled water. I think a gravity of 1.060. This becomes a IPLager or something. Just wondering if anyone has experience or thoughts on the out come...bitterness? Beer me any concerns you might have or even an old fashion "go for it buddy".

 

[VikeMan]

Yes, you can do this. But 4 gallons of 1.080 wort plus 2 gallons of water yields a gravity of 1.053 (not 1.060).

((1.080 - 1) x 4 ) + (0 x 2)
--------------------------- + 1 = 1.053
4 + 2

Since you mentioned bitterness, you can roughly figure that the IBUs will be diluted the same way gravity was. Say the base wort produces a beer with 60 IBUs:

(60 x 4) + (0 x 2)
------------------ = 40 IBUs
4 + 2

 

[Angell]

oh yea math... Vary cool! Actually 1.053 is better.

Thanks for the reply!