Boil volume for extract brews

Hello -

First off, thanks for making a great product. I recently tried ProMash just to see what it was like and I was baffled by it. Beer Smith is so easy to use!

I do have a problem, however. I have done a series of extract brews and have been refining my numbers in terms of boil loss and trub/kettle loss. So, I have been making adjustments as needed. I realized recently, though, that these adjustments are not factored in to the original gravity estimate--even though they are factored into the boil volume. It seems no matter what you do to the boil volume, the original gravity remains the same. I saw a post recently that explained this is because OG is a factor of brewhouse efficiency. But it seems that brewhouse efficiency is fixed at 78% for extract brews. This is a problem for me because I try to leave as much trub as I can and don't tilt the kettle to get the last drop. I have about 1.4 gallons of wort and trub left behind. This means my actually OGs are much lower than I expect.

What can I do to make my OG estimates more accurate? Is there any way to override the fixed extract efficiency of 78%?

Thanks for your help,
Chris

Chris,
  The overall efficiency and indeed the OG depends on your final volume, not the boil volume (particularly for extracts).  The effect you are describing is not necessarily a function of the boil volume, but instead the trub losses you are experiencing.  Obviously you are losing OG points to the trub loss.

  Several people have raised this as an issue (both mash tun losses and trub losses) recently.  Normally these losses are accounted for in the overall efficiency, but I am seriously considering offering an option to allow for an alternate method of estimating OG that would account for trub/mash/boil losses at each stage to give an alternative gravity estimate.  In cases where losses are substantial this would provide a more accurate number. 

Cheers!
Brad