I've been having some issues with the last few batches I've brewed. I've been getting pretty consistent OG yields (70% or so) mashing for an hour with a ten gallon igloo cooler at 152-154 degrees. I bought a refractometer and have had OGs of 1.061, 1.066 and 1.071. using fresh dry yeast, I've pitched two packets of US-05 for each of these (sierra pale clone and two IPAs), let ferment in a 60-65 degree room for 2-3 weeks in primary, and the yeast has pooped out around 1.030 for all three.
I've been using beersmith, and I know I'm mashing a bit on the high side (I like some extra body) but I should still end up with FG in the 1.0teens. I'm missing my final mark by a full twenty points, which makes for some weak (though not unenjoyable) beer. I just can't figure out why. the yeast is fresh, only a couple months old and kept in the fridge, warmed to room temperature prior to hydrating. 350+ billion cells should be more than adequate for those OGs. I've left them primary a full week or two after airlock activity has ceased, and I've done plenty of aeration of the wort prior to pitching. I don't have much control over the fermenting room temp, but so far this year it hasn't gone over 70 degrees in there.
any ideas what I might be doing wrong?
I'm taking a couple of these to my club meeting tonight (north seattle homebrewers), and plan to bring them to NHC assuming they pass muster with my club.