[Robert]

Thanks, Big Monk, I'm looking at that right now.

I just PM'd you my sheet that I modified. It is expanded to include the Novotny equations as well and reworks some of the Attenuation and Alcohol calcs as well to more accurate versions.

Hands down, your sheet is the best thing I've seen yet.  Comprehensive and clear.  Thanks much!

[Robert]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

[Big Monk]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.

[klickitat jim]

Which Terrill would also be known as "linear"? That's what the Refractometer Calc app uses... Which I use too

My typical attenuation is 75-80%

[Robert]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.

Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

[Big Monk]

Which Terrill would also be known as "linear"? That's what the Refractometer Calc app uses... Which I use too

My typical attenuation is 75-80%

If you download Sean’s excel sheet, he has them labeled. It’s essentially the Cubic equation with the squared and cubed terms left off.

[Big Monk]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.

Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.

[klickitat jim]

I can only think of a few possible reasons. If you do a mid fermentation temp change. If you are tracking rate of fermentation. If you just have morbid curiosity and can't help but fiddle with things. Personally, I've done them all but they aren't really vital, at all

[Robert]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.

Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.

I check mid fermentation because, fermenting lagers with 34/70, I let the temperature start to free rise at about 50% apparent attenuation.  But honestly, I don't use a gravity reading as my cue.  With countless batches behind me, I know by the number of hours from pitching when to cut attemperation.  But I do take a sample and check gravity just because if it were much higher or lower than expected at that point in time, that would indicate a problem with yeast, and I wouldn't repitch.  But for that purpose I can easily live with an error of +/- 0.5°P.  Or a bit more.

[Big Monk]

Hydrometer: 1.012.  Refractometer WRIf: 6.  OG: 12.4°P.  Correction factor: 0.97. New Cubic wins again: sg1.0119.

I find new Cubic to be the most accurate for me. I typically have Attenuation in the upper 80s and new Cubic seems to favor high Attenuation. New linear seems to work well for Attenuation in the low 80s.

Checking back through my numbers, Novotny would overshoot on every batch.

Derek, it's looking pretty clear to me that new cubic is most accurate for FG.  But do you have any insight yet into whether Novotný is closer on partially fermented beer, or is that jury still out?

Honestly I don’t. I have to question whether there is even any utility in knowing mid fermentation gravity. When we spund, we are typically doing it with 4 points or so remaining and that’s close enough to final gravity that Terrill’s equation are bang on for me and most of the rest of the LOB crowd.

Maybe I’m being a bit short sighted? Is there a reason why we would even care about mid fermantion gravity? If not, then that gets rid of one of the major selling points for the Novotny equations. Add that to the fact that, for my beers at least, it’s wildly innacurate (estimated a correlation far lower than actual).

I do plan on entering data into my modified sheet over the next 10 batches or so and seeing how it turns out.

I check mid fermentation because, fermenting lagers with 34/70, I let the temperature start to free rise at about 50% apparent attenuation.  But honestly, I don't use a gravity reading as my cue.  With countless batches behind me, I know by the number of hours from pitching when to cut attemperation.  But I do take a sample and check gravity just because if it were much higher or lower than expected at that point in time, that would indicate a problem with yeast, and I wouldn't repitch.  But for that purpose I can easily live with an error of +/- 0.5°P.  Or a bit more.

The good thing is, if you track across a number of batches at different points and check with a hydrometer, you will then have a data set that are let’s you tell yourself which correlation works for which stage in fermentation.

[Robert]

^^^^
Really, I'm thinking I can just start using a refractometer for the midway check and learn a new benchmark.   If the refractometer regularly reads x °P at y hours, that's all I need to know to track consistent yeast performance.  The "real" number is irrelevant. But knowing the right correction would be nice.  Maybe just a little anal.

[Robert]

FWIW made one more actual comparison with hydrometer on another batch at FG today.  Terill new cubic dead on.  Done with this.

[Big Monk]

FWIW made one more actual comparison with hydrometer on another batch at FG today.  Terill new cubic dead on.  Done with this.

For me it’s New Linear in the 78-82% AA range and New Cubic in the 83-89% AA range.

[dmtaylor]

This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

[Big Monk]

This is crazy.  We're all getting different answers.  Novotny and Old Cubic are most accurate for mine all the way across.

I modified my sheet to calculate attenuation and alcohol for each correlation and entered in stats from 12 sessions. Novotny Linear and Cubic and Old Cubic WAY undershot every batch and returned unrealistic attenuation and ABV Numbers.