EDIT: Some of the info below is incorrect. Please read this thread by bundy. As explained in this post, just use 21.82 L for the VAW of BCS recipes.]
This post relates again to Brewing Classic Styles Recipes and contains an updated 'fix'. It also answers skinks question from the first post in
The Chronicles of Skink 
.
[Some of the below may be repetitive as I initially was going to post it in another thread.]
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Adjusting the Hop Bill in Brewing Classic Styles Recipes[/center]
In any BCS (Brewing Classic Styles) recipe we are dealing with two discrepancies...
1. The recipe IBU's are based on the Rager hop IBU estimate formula.
2. The recipes are essentially extract recipes with an annotation at the end that converts them to all-grain.
Number 1 above is rarely dealt with anywhere apart from here and I've never seen number 2 dealt with on any other site. The touchstone though, that no one talks about, is that all-grain recipes will require more hops than an extract recipe because the extra trub etc 'grabs' oils out of the wort and then 'hangs onto' them.
My last answer on this in this thread for BCS recipes has been to just type the IBU number into the second line of Section D of the BIABacus because the Rager formula
usually reads higher on most recipes. So, doing this would force you to use more hops on most recipes. But, I think that advice is probably wrong. It's just too much of a generalisation. Here's a screenshot from BeerSmith...
IBU Discrepancies 2.JPG
I think the last time I looked at this I used a different screenshot and nearly all recipes read higher in Rager. But, look at the above. The variations and anomalies are much greater than I originally thought. It was silly of me though to even suggest a solution based on such a strange formula as Rager. So, here is my next best guess at how to deal with this...
Latest Advice on BCS Recipes [See edit at beginning of this post.]
What we really need to be doing here is taking a guess at what no one has guessed at before (that I know of). We need to decide what percentage of hops we need to add extra to an all-grain brew compared to an extract. I've won quite a lot of Silvers just brewing BCS recipes but the majority of negative comments said, "Slightly under-hopped." In light of this...
My best guess on how to deal with this is to increase the hop bill by 12.5%.
The easiest way to do this in the BIABacus with BCS recipes is to make the first line of Section D read 20.19 L.
Note that this will affect the colour estimate of the original formula but not of the scaled formula.
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