TandemTails
Well-Known Member
I've been trying to figure out what the heck is going on with my beersmith calculations and simply can't figure out what the problem is. In the last half dozen brews I've done I've hit my pre-boil gravity and post boil volume dead on (or slightly higher gravity pre-boil) but my OG is significantly lower than what beersmith predicts.
Here are some examples:
Imperial Brown Ale:
* Predicted pre-boil vol/sg: 8.79 gal / 1.069
* Actual pre-boil vol/sg: 8.85 gal / 1.067
* Predicted post-boil vol/sg: 6.5 gal / 1.086
* Actual post-boil vol / sg: 6.5 gal / 1.080
Belgian Blond Ale:
(if I hadn't started with a higher pre-boil grav and ended up with more boil-off, this would have been way off)
* Predicted pre-boil vol/sg: 7.98 gal / 1.043
* Actual pre-boil vol/sg: 8 gal / 1.046
* Predicted post-boil vol/sg: 5 gal / 1.068
* Actual post-boil vol / sg: 4.5 gal / 1.067
Barleywine:
(this one was slightly higher vol due to boil length issue)
* Predicted pre-boil vol/sg: 7.69 gal / 1.057
* Actual pre-boil vol/sg: 7.7 gal / 1.058
* Predicted post-boil vol/sg: 4 gal / 1.098
* Actual post-boil vol / sg: 4.25 gal / 1.086
This obviously isn't an issue with the mash. My BH efficiency is set to 68 although I do adjust it slightly down for some of the bigger beers. I don't see how that would affect the preboil->postboil gravity math though.
Any thoughts on what I can do to adjust this up correctly?
Here are some examples:
Imperial Brown Ale:
* Predicted pre-boil vol/sg: 8.79 gal / 1.069
* Actual pre-boil vol/sg: 8.85 gal / 1.067
* Predicted post-boil vol/sg: 6.5 gal / 1.086
* Actual post-boil vol / sg: 6.5 gal / 1.080
Belgian Blond Ale:
(if I hadn't started with a higher pre-boil grav and ended up with more boil-off, this would have been way off)
* Predicted pre-boil vol/sg: 7.98 gal / 1.043
* Actual pre-boil vol/sg: 8 gal / 1.046
* Predicted post-boil vol/sg: 5 gal / 1.068
* Actual post-boil vol / sg: 4.5 gal / 1.067
Barleywine:
(this one was slightly higher vol due to boil length issue)
* Predicted pre-boil vol/sg: 7.69 gal / 1.057
* Actual pre-boil vol/sg: 7.7 gal / 1.058
* Predicted post-boil vol/sg: 4 gal / 1.098
* Actual post-boil vol / sg: 4.25 gal / 1.086
This obviously isn't an issue with the mash. My BH efficiency is set to 68 although I do adjust it slightly down for some of the bigger beers. I don't see how that would affect the preboil->postboil gravity math though.
Any thoughts on what I can do to adjust this up correctly?