« on: February 13, 2015, 07:50:05 AM »
1. temperature swings are never good, the lower temperature may have caused active yeast to flocculate out.
2. By expected FG "1.05" I think you meant 1.005. I don't put much into expected FG calculations. This is a pretty low FG, especially for the Irish Ale yeast IME. Still, I think you could have gotten lower than you did had you not dropped the temperature.
3. That's an awfully high amount of specialty malt as a percentage of your total grain bill. I'm not sure how fermentable victory malt is so someone else can chime in.
As to your questions, yes you could pitch more yeast buy I'd make sure it's an active starter- but at this point you are at 66% apparent attenuation so I'd just leave it.
You could add a simple sugar to raise ABV but it would mess up the flavor and body for this style and I the yeast aren't active it wouldn't get fermented anyway.
Finally, I don't think the volume of sparge water would effect fermentability, just the original gravity. Fermentability has more to due with the grain bill, mash temp and technique.
I'd try swirling the fermentor gently a bit to rouse the yeast and move it back to 70F for a week. If that doesn't help I'd just leave it and enjoy a lower abv beer.