Planning first All-Grain BIAB - calculated ABV too low

[UnclePeaches]

I am planning my first all-grain (brew-in-a-bag) brew day for this coming Friday and have noticed a potential problem I want to figure out before I even turn on my stove.
I am brewing BierMuncher's Cream of Three Crops in a 5 gallon pot which I plan to top to 5.5 gallons in my fermenter. I don't currently own any brewing software and used BrewersFriend.com for my calculations. When I plug in all of my numbers it tells me my final ABV will be 3.17% when this beer should have an ABV of 4%-5%.
What am I missing/not accounting for and how can I correct this before I get started?

Here are the particulars:

• I am brewing in a 5 gallon pot
• My BIAB mash volume is 3 gallons
• I plan to dunk sparge with 1.5 gallons
• My boil volume is 4.5 gallons with an estimated 1 gallon boil-off
• After boil & chilling I plan to top up my fermenter with water to reach 5.5 gallons
• http://www.brewersfriend.com/homebrew/recipe/view/10545/cream-of-three-crops

Cream of Three Crops
Method: BIAB
Style: Cream Ale
Boil Time: 90 min
Batch Size: 5.5 gallons
Boil Size: 4.5 gallons
Efficiency: 60%
Source: BierMuncher https://www.homebrewtalk.com/f62/cream-three-crops-cream-ale-66503/
Original Gravity: 1.034
Final Gravity: 1.009
ABV (standard): 3.17%
IBU (tinseth): 14.38
SRM (morey): 2.48

FERMENTABLES & ADJUNCTS
5.74 lb Pale 2-Row
1.91 lb Flaked Corn
0.48 lb Flaked Rice
0.24 lb Rice Hulls

HOPS
0.48 oz Willamette 60 min
0.48 oz Crystal 60 min

MASH
BIAB - 152°F 90 min

OTHER
1 Whirlfloc Tablet 15 min

YEAST
Fermentis/Safale - American Ale Yeast US-05

PRIMARY
14 Days at 68°F

SECONDARY
Add gelatin finings
7 Days at 68°F

BOTTLE & CARBONATE
2 weeks

many thanks,
-pj

 

[billl]

Your OG is down 6 points and your FG is up 4 points.

The OG is being driven by your efficiency of 60% compared to the original recipes 75%. Since this is your first batch, you really don't know what efficiency you are going to get. You should just keep some DME on hand in case you miss those %'s. Also, unless you are just dying to use your new digital scale, save yourself some headaches and just use 6, 2, and 0.5 lbs. The uncertainty in your mash performance is going to make worrying about hundredths of a pound of grain pretty pointless.

Your FG is high because the program is defaulting to 74% attenuation. The posted recipe is showing 87% - which seems pretty high. I haven't used that yeast, but it is supposed to be similar to WY1056. I'm usually around 80% for that

 

[LLBeanJ]

Are you really planning on a 90 minute boil? If so, you'll lose more than a gallon to boiloff, at least 1.5 gal, probably more. Since you have no Pilsener in the grain bill, a 60 min boil should suffice.

Also, you can leave out the rice hulls, since you're doing BIAB.

 

[Kaz]

I agree....60 minute boil, the 90 minute boil is unnecessary and could darken your beer. I also agree...drop the rice hulls, not needed with BIAB. Its the low efficiency in the recipe calculator that is dropping your OG. If you have a bag that fits nice and loose in your kettle, your grains are milled pretty fine and you squeeze and press the crap out of that bag when you're done...its quite possible to get BIAB efficiencies between 80-90% but you won't know that until after your first batch.

 

[UnclePeaches]

Thanks for all the input. The 60% efficiency was just a guess... assuming that my inexperience will result in something well below the efficiencies I see people here on HBT typically achieving. I'll change my estimate to a 75% efficiency and remember Kaz's advice re: a loose bag, good crush, and tight squeeze.

As for the 90 minute boil, I took that directly from BierMuncher:
https://www.homebrewtalk.com/f62/cream-three-crops-cream-ale-66503/#post684426
After reading the extensive posts tacked onto BierMuncher's recipe (1322 & counting) and people's success using a 90 minute boil with this specific recipe, I'm going to keep it, but am glad of LLBeanJ's reminder to account for a larger boil-off and will adjust to 1.5 gallons.

Thanks,
PJ