Anyone brew Brown Porter from latest BYO?

[ChiechiBrouw]

I brewed the "Brown Porter" from the latest BYO (I don't have the issue in front of me, but the cover is of the head brewer from Brooklyn Brewing). When I plugged the recipe into BeerSmith, the IBUs came up short--way short. The target was 28, but the as-written recipe came up around 18 (30 g of 5% @ 60 min). Anyway, I compensated by adding more at 60 min such that BeerSmith said the IBUs would be 28 exactly (and left the late addition alone).

I'm curious if anyone else has tried this recipe, and if they found the same IBU mis-match... Is it a type-O, or am I stupid? BeerSmith has yet to let me down, but neither has BYO...

 

[Piratwolf]

Did they talk about whirlpooling in the recipe? I wouldn't think so for a brown, but apparently it's an increasingly common practice at craft breweries to get more IBUs from the so-called aroma hops...and some software doesn't calculate that at all.

 

[ChiechiBrouw]

I didn't see anything special like that... Just a "normal" BYO recipe.

 

[zgoda]

It depends on how they calculated bitterness units - either Rager or Tinseth formula yields different results (higher yield with Rager).