Help with Low ABV

Greetings to all. This is my first post - so please go easy on me, and I thank you in advance for your help.

I began Homebrewing with a starter kit for Christmas 2013. Since then, I have only brewed 6 batches, including 1 hopped-extract no boil kit (3gal), 4 malt extract w/ specialty grain 60-minute boil kits (5gal), and 1 homemade Sweet Mead recipe (5 gal).

My specific question, submitted for your collective consideration, has to do with the low %ABV with my most recent 60-minute boil kit, an Irish Stout recipe from Midwest Supplies.

According to Midwest Supplies, the recipe contained:
• 9 lbs. Domestic 2-Row barley
• 8 oz. Chocolate Malt
• 8 oz. Caramel 10°L
• 8 oz. Roasted Barley
• 4 oz. Flaked Barley
• 1 oz. Nugget hops (instructions called for ½ oz. – so only I used ½ oz.)
• 1 oz. Willamette hops
• White Labs WLP004 Irish Ale yeast (my selection)
• Priming sugar

According to instructions, the Gravity range should have been:
• OG: 1.042 – 1.046
• FG: 1.010 – 1.012

I sanitize everything that touches the wort/beer with BrewVint “Cleanitizer” 6891, and prepared the recipe kit according to instructions.

So, here are the facts around this batch:
• OG: 1.04 (to be fair, I did not record this measure to the 1000th)
• Fermented 6 DAYS at 64°F in 6-Gal plastic fermenter bucket with S-type Bubbler Airlock (until no further airlock activity)
• Racked for secondary fermentation, 16 days at 70°F in plastic 5-Gal Carboy
• FG: 1.015
• ABV: 3.3%

According to the %ABV range included in the instructions, and assuming my calculations are correct - the high range was 4.73%, with the low range of 3.94%.

Could anyone offer advice on what might have caused the lower than expected ABV for this particular batch?

Secondarily, is there anything I might do differently next time to get a “higher” than advertised %ABV for a similar recipe? I strongly favor a “Guinness”-style Irish Ale, but wish it had a higher %ABV, say 6.0-6.5%.

Thank you again for your consideration, and any helpful perspective would be greatly appreciated.

The lower starting gravity is likely due to the volume of water you used in the boil or for topping up (ie, too much) or an error in measurement. When I first started brewing I was getting super low OGs and was perplexed, as I was using extract and very specific water volume. What I didn't take into account it that I was topping up the fermentor with spring water, then taking the gravity sample from the top. The wort and top up water did not mix completely, so I ended up recording a much lower gravity than my wort actually was.

As for the FG, I think the most likely issue is that you transferred it too early. When you transfer you lose a lot of yeast at the bottom of the fermentor, which is kind of the point of transferring for most people. But if you beer hasn't hit FG (or near to it), you likely won't have enough yeast present to finish the fermentation.

The way to avoid this is to only use the airlock as a guide, and take gravity readings before you transfer. If the gravity readings are near your anticipated FG and remain the same for 3 days, you are safe to transfer. Many people advocate leaving the beer on the yeast cake for several days-weeks after this, though, to allow the yeast to consume the by-products of fermentation that can lead to off-flavors.

Key points:
-Make sure wort is the right volume
-Make sure wort is mixed properly before measuring OG if using top up water
-Use hydrometer measurements to decide when to transfer, not airlock.

Hope that helps!