Could I get some math help?

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tlarham

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I'm an English/Theatre teacher...numbers and I have a fundamental communication flaw; if there is anyone for whom the gift of arithmetic is strong, I would be most appreciative of some assistance.

Since I started using a heatstick with my boil, I've enjoyed a more vigorous bubble...and suddenly my fermenter is not filling to the level it should.

Beersmith (awesome!) is set for 11% boiloff...for a 5.5 gallon batch, it says I should be starting with 7 gallons. I followed it to the letter and ended with exactly 5 gallons (accounting for .5 gallons left of trub).

Question #1: To what should I set my boiloff to end with the correct final amount. My guess is around 13% using the genetically bad math.

Second issue...I have Beersmith set for 70% efficiency -- with my recipe, I was supposed to have a original gravity of 1.045 (5.5 gallons). My measured OG was 1.058 (at 5 gallons...which is more than can be accounted for by the increased boiloff, correct?)

Question #2: What is my efficiency?

Any help is greatly appreciated.

-- T.

EDIT: Fixed FG/OG error
 
ill take question #1 for $500. probably no one here can tell you your exact boil off. it is dependent on many variables including your equipment and environmental conditions. trial and error is the best way to determine the value.
 
Not that you asked, but..
I think you have some nomenclature off. The Original Gravity (OG) is before you pitch yeast. The Final Gravity (FG) is after it is done fermenting.
Cheers, Jeff
 
Not that you asked, but..
I think you have some nomenclature off. The Original Gravity (OG) is before you pitch yeast. The Final Gravity (FG) is after it is done fermenting.
Cheers, Jeff

you need to change you gender Jeff:D. Unless Jeff is the new Jessica
 
Not that you asked, but..
I think you have some nomenclature off. The Original Gravity (OG) is before you pitch yeast. The Final Gravity (FG) is after it is done fermenting.
Cheers, Jeff

Bugger -- thanks for catching that. Fixed now.
 
I would say that you could do the math on both of these. but I would determine them with careful notes (which it sounds like you do take).

After a batch I just raise the efficiency in my software til i get to my original gravity. It might not be the best (most exact) way but, after about 2 brews I can now predict pretty well.

same with boil off. It *is* a lot of factors, so just turn up the rate until you see the numbers that you got this time and see if they work next time. then adjust again.
 
Beersmith (awesome!) is set for 11% boiloff...for a 5.5 gallon batch, it says I should be starting with 7 gallons. I followed it to the letter and ended with exactly 5 gallons (accounting for .5 gallons left of trub).

Question #1: To what should I set my boiloff to end with the correct final amount. My guess is around 13% using the genetically bad math.
Your actual boiloff was 1.5/7 = 21%. That's a lot... However, if it happened to be a 90 minute boil, it would be a more reasonable 21/1.5 = 14%. Note, however, that it doesn't matter all that much if you over-boil, because you can always add top-off water to get back to your desired volume. Better to end up with too little than too much.

Second issue...I have Beersmith set for 70% efficiency -- with my recipe, I was supposed to have a original gravity of 1.045 (5.5 gallons). My measured OG was 1.058 (at 5 gallons...which is more than can be accounted for by the increased boiloff, correct?)

Question #2: What is my efficiency?

1.045 at 5.5 gallons would translate to 1.050 at 5 gallons (5.5 x .045 / 5), so yes - your efficiency is greater than 70%. Looks to me more like 81% (.058 / .050 * .7).
 
I'm an English/Theatre teacher...numbers and I have a fundamental communication flaw...

Don't think for a minute that you need to be a math wiz to make great beer. A lot of the rhetoric on the forum is presented by people. and for people who are good at that type of thing and want to "accurately quantify" the process.

Basicly from the results of your previous batch, if your final volume was say a 1/2 gallon low, you therefore know that on subsequent batches that your preboil volume should be increased by the amount you were low.

Same basic principle can be applied to your gravities as well. If on the high side, just cut back your base malt accordingly to get closer to your goal. With practice, it will become second nature.
 
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