Originally Posted by Pilgarlic
Anytime I go over 6% abv my concern with the yeast finishing increases. The way to deal with that concern is to pitch a sufficient quantity of healthy yeast (make a good starter), pitch it at the right temp (at or a bit below your fermentation temp), properly aerate or oxygenate the wort (for a beer of this size I use a shot of oxygen, at minimum vigorously shake it for five minutes) and manage your fermentation temp until it's finished (keep it consistent throughout active fermentation and bring it up some as activity wanes). Good luck.
In addition it definitely is relevant to know the type of yeast strain you are using and the rating of flocculation it has. I fou are using a yeast rated with high flocculation than the chances of it dropping out prematurely are greater than a low flocculating yeast and your fermentation temperatures will play into this.
For example if you ferment a high flocculating yeast at a lwer than optimal temperature than the yeast will simply drop out before finishing their task.
If you post your recipe and yeast we can assist you further with getting it pitched and fermented properly