discrepancy in O.G. readings

Hey guys,

I just brewed a Bavarian Weiss beer today and had a few weird numbers and was hoping I could get some help.

I had a target O.G. of 52 with an estimated preboil volume of 6.75 gal. and post boil 5.5 gal.

After lauter, my preboil O.G. was 49 at 6.75 gal. I boiled for 60 minutes and I boiled off 1.75 gallons to get down to 5, but only with a post boil O.G. of 52. I hit my target O.G. exactly which is cool, but I'm not sure how after boiling off 1.75 gallons the gravity only changed 3 units. Based on my calculations from "Designing Great Beers" I should have had a post boil O.G. of 66.

All gravity readings were corrected for temperature, so there's not an issue there. So is this normal, I'm not sure what happened, so any help would be great.

I wonder if what's going on here is the accuracy of the correction formula you're using. I've read other threads that suggest that correction is only accurate close the the hydro's calibration temp (usually 60F)

Hex23 said:

I wonder if what's going on here is the accuracy of the correction formula you're using. I've read other threads that suggest that correction is only accurate close the the hydro's calibration temp (usually 60F)

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possibly, I also have the iBrewmaster app on my phone and it calculates the O.G. at 60 post boil, with an O.G. of 50 preboil. So either way there is something missing. I appreciate the response.