After a couple of weeks of fermenting with very little disturbance does the alcohol rise to the top of the fermenter since it is has a low SG? Reason I'm asking, if I were to take a SG reading by just dropping my hydrometer it in the fermenter, would I get a different result than if I used a beer thief which basically takes the majority of the beer from +/- 12" below the surface?
I think you're fine taking a reading from the top. At least that's how I do it and I seem to get accurate readings.
I place the hydrometer directly into a bucket fermenter or bottling bucket, but use a thief for OG to get the hydrometer out of the foam, or to get a reading out of my carboy. After doing this with the same beer going from a bucket to a carboy I am pretty sure the numbers don't change by doing it either way. And Bob is right, alcohol and water dissolve completely into each other.
