How to unstick a stuck fermentation

[gfullam]

I am brewing the Brewer's Best Russian Imperial Stout 5 gallon kit and it has been stuck at the same SG for two weeks now.

I should mention that primary fermentation was explosive – literally, with CO2 and foam forming so vigorously that my fermentation bucket lid blew right off about 12 hours after pitching. It appeared as though all of the fermentation happened in about 3-5 days.

I have done two hydrometer readings so far, once at racking to secondary and then tonight (2 weeks in secondary).

It appears to have stopped fermenting at 1.034 SG (down from 1.080 OG). The target FG is 1.017-1.020 so I'm not sure what to do.

I have attempted stirring it with a paddle and rocking it vigorously, but the reading has stayed the same.

Should I repitch the same yeast?
Should I repitch a different yeast; like a dry wine yeast or killer strain yeast?
Or is there another solution?

BTW the beer tasted great at each reading. It tastes clean, no off flavors, just not nearly as much alcohol as I was hoping for.

 

[KuntzBrewing]

What was your mash schedule like? What temp and how long?

 

[Kayos]

What temp are you fermenting at?

1. Move to warmer area to ferment
2. Pitch the same yeast strain again (what was it) and make a starter

 

[ChadChaney]

I had the same problem with a RIS, I did not make an adequate starter and stalled around the same area. I pitched a pack of Champagne yeast, not worrying about the dryness since I was racking to a secondary on cacao nibs and port soaked oak cubes, and hit the desired FG. Interestingly, absolutely no airlock activity and very little visible signs of fermentation, but the gravity kept moving. Nottingham would work too.

 

[gfullam]

I apologize to all who replied for not getting back quickly. I didn't even wait for a response before I went to plan B, which was:

1 sachet Lalvin EC-1118 Dry Champagne yeast

I mixed up a starter, pitched it and agitated by rocking the fermenter.

I saw little to no airlock activity since, which has been over four weeks now. So, I decided to thief some for a hydrometer test, which yielded disappointing results.

With the values below, using Dave's Dreaded Actual Specific Gravity Calculator (http://dd26943.com/davesdreaded/tools/convert.htm) I calculate only 6.9% ABV and only 49% attenuation.

2012-01-07 OG 1.080 @ 82 F
2012-01-16 SG 1.034 @ 66 F
2012-01-30 SG 1.034 @ 66 F (posted this thread to seek help on stuck fermentation)
2012-02-01 Pitched 1 sachet Lalvin EC-1118 Dry Champagne yeast
2012-03-03 SG 1.030 @ 68 F

Do I have any effective alternative's to boost the ABV at this point or is it wise to just leave it alone?

I don't want to risk ruining it — it tastes great.

 

[gfullam]

KuntzBrewing, I only did a partial mash, as it was a Brewer's Best kit:

I steeped the grains in 2.5 gal of clean water between 150-165 F for 20 min.

Brought to boil and added LME, DME and Maltodextrin.
Added bittering hops; boiled 40 min.
Added aroma hops and chipotle powder; boiled for 20 min.
Terminated boil. Total boil time 60 min.

Only cooled to 82 F before pitching Safale S-04 dry ale yeast packet and experienced an explosive fermentation that blew the top off my fermenter in 12 hours.

After cleaning up and resealing the fermenter, it continued having constant airlock activity for about three days then stopped.

Whatever advice you can give based on that information would be appreciated.

 

[Polboy]

i think the only way to go now is to add some amylase enzyme

 

[pdxal]

Why mess with a beer that tastes great and is finished fermenting?
Call it a draw and enjoy it.
It looks like you have lots of unfermentables in the wort, anyway. Maltodextrin won't ferment, LME and DME generally have a good amount of crystal malt in them which won't ferment, and your partial mash wasn't much of a mash if the temp was much above 155 for any of that short 20 minute period.
Champagne yeast eats sugars, not dextrins, so if your S-04 had pooped out and not finished fermenting the sugars it would have brought your FG down a bunch in that 4 weeks.
Chalk it up to experience and enjoy the beer, even if it is not exactly what you expected.