Too high FG

[Hastings]

I brewed a porter about a month and a half ago and i started with a OG of 1.05 and i checked 3 weeks ago and it was higher then 1.03 and for some reason now it has only fermented to 1.03. Should i shake it up a little more and put a blanket it over it to keep it warmer cause it has been pretty cool in New York or has it been fermenting for way to long?

Thank You

 

[BenjaminJonah]

What type of yeast did you use? Most ferment best at around 70-75 if its an ale yeast. At least thats what I have found. Otherwise the yeast wont be as active.

 

[Jebu1788]

There are a number of reasons that this could be. What temperature are you fermenting now? Ale yeast does take longer usually at colder temperatures, but depending on the yeast too. So what yeast did you use? Check the recommended fermentation temperatures. Usually 70-75 is on the high side, but may be reasonable.

Don't shake the beer though. (Oxygen in the beer at this point is bad) You could try swirling it gently though to rouse some of the yeast.

Finally, was this all grain? What temperature did you mash at? A month and a half does seem like plenty of time to ferment out, so you may just have a sweet, low abv porter.