Ordinarily when I brew a beer I will leave it happily fermenting away for at least a week before I concern myself with how things are progressing. On this occasion two things have led me to take a look earlier than normal. Firstly the yeast I used was a liquid yeast and normally it is not advised to use a liquid yeast if it is more than 6 months from its manufacture date. My yeast was seven months from its date of manufacture, due to this I was expecting to have to either pitch a packet of dry yeast on top of the liquid yeast, or be very patient and wait for fermentation to build very slowly.
The second reason I was interested in finding out where things were at with this beer was that, considering point one above, I was surprised to watch fermentation take off like a rocket. Within six hours of pitching the yeast I had airlock activity and by 18 hours the airlock was bubbling a couple of times a second, which is probably the most aggressive fermentation I have seen for a while.
The result of this, after 4 days fermentation, 1016. Target for this beer is 1012 and I would expect it to achieve that over the next week or so. The plan is to leave this beer in primary for another 7-10 days, I will then transfer to secondary and dry hop with some cascade.
Oh, it tastes pretty good as well.