Beersmith - lowered LME amount and IBU's increased?

[americancracka]

Using Beersmith:

Original= 6.6lbs Pale Malt, Maris Otter [Boil for 60 min]
IBU = 98.1

Change:
3 lbs 4.8 oz Pale Malt, Maris Otter [Boil for 60 min]
3 lbs 4.8 oz Pale Malt, Maris Otter [Boil for 0 min]
IBU = 160.4

That is the ONLY change.
Why would my IBU go up?
Thanks!

 

[Yooper]

Using Beersmith:

Original= 6.6lbs Pale Malt, Maris Otter [Boil for 60 min]
IBU = 98.1

Change:
3 lbs 4.8 oz Pale Malt, Maris Otter [Boil for 60 min]
3 lbs 4.8 oz Pale Malt, Maris Otter [Boil for 0 min]
IBU = 160.4

That is the ONLY change.
Why would my IBU go up?
Thanks!

It really wouldn't- but the Beersmith software calculates the IBUs partially based on the wort gravity. By adding half the extract at the end of the boil (a good thing, actually), it calculates the IBUs higher. It's not accurate, as it's impossible to get more than about 100 IBUs in any wort anyway, but that's why it has such a change.

 

[americancracka]

Thanks a ton Yooper. I was hoping it was a software glitch.