Forgot to measure OG. How to determine ABV?

[KPBrews]

Hullo, brewers!

After a series of near-disasters this past weekend (not really related to my brewing skills or lack thereof, just... stuff happening), I finally have my second batch of Deception Cream Stout in the fermentation bucket, as of about 4:15 yesterday afternoon. So we're now roughly 26.5 hours into it.

I had a "OH, CRUD!" moment earlier today, when I was looking at my brew notes, realizing that yesterday, in the rush to finish while solving a series last-minute issues (long story, not relevant), I managed to completely forget to take my OG reading before pitching and sealing up the bucket.

I know I can always pop it open and take a reading, but will that mess anything up? I'm using a Hydrometer so I'd need to pull out a fair amount of wort (and whatever yeast get slurped up in the process) to measure. I'm not sure if active fermentation has begun or not. (I'm still at work, but headed back home shortly, so I can't tell if there is airlock activity or krausen yet)

So, at this point, would I actually get a reasonably accurate OG reading? Or perhaps more importantly, is there an alternate way for me to determine final ABV without those OG/FG readings?

This is my second time making this recipe. (First one came out great!) I'll be leaving it in the primary bucket for at least a month, and then kegging it, so I'm really not worried about bottle bombs or anything like that. I suppose the ABV is really only a basic point of information ... as long as it tastes as good as the first batch, I'll be happy. But it's still nice to know, if only for my notes.

So what are my options? Thanks!

(I did search a bit, but with terms this generic I wasn't having much luck, so here we go...)

 

[BrewSRQ]

All grain, extract, kit? Also what did you pitch? An active starter, some dry yeast?

 

[chickypad]

If this was an extract recipe and your volumes are on then you can just go by the recipe expected OG. With extract there is a known amount of sugars being added, you can't really miss. If all grain then that's more of a problem. Most of my beers are fermenting away 27 hrs in so I wouldn't rely on a reading now. If you have your process dialed in then hopefully your efficiency hasn't changed too much and you can go by prior batches, especially if you've actually made this recipe before.

 

[KPBrews]

Sorry, I was brewing the Deception Cream Stout from the Extract recipe in this thread:
https://www.homebrewtalk.com/showthread.php?t=141483

I pitched activated Safale US-05 (activated in sanitized 85 degree water about 20 min before pitching/pouring it all in).

I'm sure my numbers will be in line with what the recipe calls for (and in line with what I produced last time I brewed it), but I still like to know, if reasonably possible.

 

[chickypad]

At this point the calculated gravity is likely to be more accurate than trying to take a reading. You just need to know your volume.

 

[KPBrews]

At this point the calculated gravity is likely to be more accurate than trying to take a reading. You just need to know your volume.

I THINK you're saying I should just go by the calculations in the original recipe, and assume I hit the target, as long as my post-boil volume was where it should be?

I think I was dead on at 5 gals, but can't be sure, as I'm using a brand new fermentation bucket, instead of my usual glass carboy, and the stupid thing has no measurement markings on it because I didn't have a chance to mark it. I had planned to use my carboy (which has carefully applied volume markings), but had to swap in the bucket, in the middle of the process, for ... reasons.

 

[BrewSRQ]

Yea I'd agree. At this point going by your calculated numbers will likely be more accurate. On the plus side, extract will be significantly more accurate since you won't have to deal with efficiency.

 

[chickypad]

I THINK you're saying I should just go by the calculations in the original recipe, and assume I hit the target, as long as my post-boil volume was where it should be?

Exactly, adding a known amount of sugar to a known volume you can accurately calculate the gravity. Of course if your volume is not known this doesn't apply.

 

[Subdivisions]

I THINK you're saying I should just go by the calculations in the original recipe, and assume I hit the target, as long as my post-boil volume was where it should be?

I think I was dead on at 5 gals, but can't be sure, as I'm using a brand new fermentation bucket, instead of my usual glass carboy, and the stupid thing has no measurement markings on it because I didn't have a chance to mark it. I had planned to use my carboy (which has carefully applied volume markings), but had to swap in the bucket, in the middle of the process, for ... reasons.

Here's a typical 6.5 gallon fermenting bucket:

The volume markings on these things suck. The first ridge above the printed 5 gallon mark is where that actual 5 gallon mark really is.

 

[KPBrews]

Here's a typical 6.5 gallon fermenting bucket:
<snip>
The volume markings on these things suck. The first ridge above the printed 5 gallon mark is where that actual 5 gallon mark really is.

The bucket in question is a Brewcraft 30 liter (8 gal) Fermenter. As it turns out, in looking for that link, I just learned that it DOES have measurement markings moulded into the plastic (white on white and so light I never noticed them... a complaint echoed in several of the reviews, too), which I would hope are relatively accurate. Until I have a chance to check them, I won't count really on them. But it shows I'm a hair under 5 gals, so it's close enough to play ball, I guess. I'll use the recipe's numbers and call it good (enough).

My glass carboys were carefully marked using a calibrated gallon pitcher, but alas, I wasn't able to use those for this batch.

FWIW, the silkscreened volume markings on my MoreBeer 6 gal bottling bucket are actually pretty spot on. I guess that "Ale Pail" is pretty craptastic, if its that far off. Good to know!

 

[RM-MN]

Look closely at your fermenter bucket. It has very little taper so you can measure the inside diameter at the top and its height and calculate its volume. Then you can measure the height of the wort and calculate that volume too. It won't be "perfect" because of the taper but probably closer than the marks on the outside. I've done that with my boil kettle so I know how far to fill it with water to start my all grain brew.

 

[KPBrews]

If I cared enough to do that much measuring and math, I probably could do that, but at this point, I think I'm close enough just going by the recipe's calculated OG. Once this batch finishes, I'll just use my calibrated gallon pitcher to verify that the moulded marking are accurate, then this won't be an issue in the future.