Low attenuation or less fermentable grains in this recipe?

[luckybeagle]

Hi all,
I brewed 7.25 gallon batch of imperial porter with the following grist, with a piddly 56% efficiency in fly sparging (bad crush + higher gravity I'm guessing):

20 lbs Maris Otter
2.5 lbs Crystal 45
2.5 lbs Chocolate Rye
2.5 lbs Brown Malt
1.25 lb Flaked Oats
1 Lb Brown Sugar

I mashed for 1 hour at 153F and fermented with Wyeast 1318 using an appropriately sized starter. Wy1318 estimates 73% attenuation.

My "FG" has been stable for 10 days at 1.029. My OG was 1.087, resulting in a 65% attenuation. The taste is a bit sweet which makes for a perfect compliment to the awaiting vanilla extract and cold brew coffee, but I am unsure if my fermentation stalled, or if the grist is less fermentable (flaked oats, character/specialty malts) than what I'm sure Wyeast is basing their attenuation percentages off of (pure, highly attenuative base malt). Though I can keg it, I'd prefer bottling and aging. I don't want bottle bombs.... Any thoughts on 1.029 reflecting complete fermentation or a stall-out?

Thank you

 

[pdxal]

First, are you measuring gravity with a hydrometer and not correcting for the presence of alcohol?
That is a lot of crystal, chocolate, and brown malt, so it could indeed not attenuate to a low FG, but it still seems a little higher FG than expected to me.

 

[grampamark]

First, are you measuring gravity with a hydrometer and not correcting for the presence of alcohol?
That is a lot of crystal, chocolate, and brown malt, so it could indeed not attenuate to a low FG, but it still seems a little higher FG than expected to me.

Did you mean to type “refractometer”? A hydrometer is the tool of choice for determining the presence of alcohol and how much of it is present.

 

[pdxal]

Did you mean to type “refractometer”? A hydrometer is the tool of choice for determining the presence of alcohol and how much of it is present.

Yep- brain fart. Thanks for catching it.

Are you measuring gravity with a refractometer, luckybeagle?

 

[luckybeagle]

Yep- brain fart. Thanks for catching it.

Are you measuring gravity with a refractometer, luckybeagle?

I use both. Refractometer for pre-boil and for OG, though I always draw off a hydrometer sample after chilling to double-check (I never use a refractometer for FG--even with the adjustments for alcohol it never seems to be accurate; I just don't trust it).

Just not entirely sure if I should bottle it, rouse up the yeast and see what happens, or pitch something else (I have more 1318, also have 3711 french saison and soon some 1084 irish ale slurry). That option is the least appealing, though.

 

[Miraculix]

My guess is, it's done. It's a bigger beer and the fg is not completely out of range.

I would try to rouse the yeast a bit, if you can do it without opening the fermenter, then wait another week or two and then bottle, if nothing happens.

Those big and dark beers are best after months of aging anyway, so you won't loose anything by waiting the extra time.

 

[Tom R]

Is it too late to do a fast fermentation test on a stir plate to estimate final gravity? I usually do them on day 2 of fermentation, but might still be useful?