Stout Recap and Question

It sounds like extra wort. With some simple math you can figure out what your gravity would have been if all of your gravity points from your extra wort were in the main wort.

Or it could just be that you overestimate your efficiency. I've come to the conclusion that I can only get to the upper 60 percents. I would love to say I get mid to upper 70s but no sense in bragging. Just learn your system.

 

Can't you just change the starting volume of your beer recipes by adding 0.5 gallons, augmenting the malt accordingly so that you hit your target gravity?

 

High gravity beers require a significantly long and hard boil to avoid having your efficiency plummet.

I did a a double sparge to get ~60% efficiency for a 1.125 RIS, and that was ~8.5 gallons for a 5.5 gallon batch, so I boiled super hard (I have a wicked burner) for 2+ hours.

 

It sounds like you need to adjust the equipment settings in Beersmith to match your systems boil off rate. You probably have the estimated brewhouse efficiency set too high as well. If I were you I would go to your equipment profile in Beersmith and adjust the boil off rate until it has you collecting about .5 gal less into the kettle than it tells you to now. Then run a few of your recipes (I would use smaller and simpler ones than this imp stout) through an efficiency calculator such as this one to find a ballpark average of what efficiency your system gets. Make sure you're entering the actual volume you ended up with for each batch.

 

If you ended up with 5.5 gallons instead of 5 gallons, and an OG of 1.070, then it's simple to figure out what your OG would have been if you had boiled away that last 0.5 gallons...

((5.5/5) x (1 - 1.070)) + 1 = 1.077

If you were expecting 1.090, then your efficiency is not as high as you were expecting. (You got 86% of whatever efficiency you were expecting, i.e. 77/90) You say this is a recurring theme, but in your previous thread you said that you are getting the efficiency that Beersmith "predicts." But if this batch is representative, then you're clearly not. I suggest reading up on mash efficiency and brewhouse efficiency. Once you understand what they mean, you'll be able to figure this stuff out, or at least ask more targeted questions.

 

http://hbd.org/uchima/tech/efficiency.html
http://www.howtobrew.com/section2/chapter12-5.html
http://beersmith.com/blog/2008/10/26/brewhouse-efficiency-for-all-grain-beer-brewing/

 

You shouldn't be guessing your efficiency and putting random numbers into your software, you should be calculating your efficiency based on the gravities you've been getting and using that to predict the efficiency of your future batches.