boil vigor

How much does the vigor of the boil matter? What is the effect of a stronger boil?

I tend to have pretty weak boils because my pot is only 30 quarts. Last night, I cranked the heat up a bit more as the wort boiled off, and got a better boil going. And it just looked different. I wonder if a lot more things were getting broken down than normally happens for me, and how this will effect the beer...?

thanks,
Scott

A rolling boil (AKA bulk boil) is where you cannot stop the boil by stirring. This ensures all of the wort is actively moving. This forces off more DMS (sulphur containing crud), makes for better hot break and better utilization. Hop resins are very sensitive to temperature, just a degree or two low can knock your IBU back 15%.

A good boil makes for better beer.

I just finished listening to a podcast by Jamil about this very issue. He explained that it should be just "ticking over" - ie rolling but not roiling! The discussion came about when brewing really light styles and trying to avoid melanoidin formation. His recommendation was to target about 10-12%/hour evaporation rate which should occur with the above boil vigour. He also mentioned this is what you will see at commercial breweries.

I'm no expert, but a heavier boil will lead to more effective bittering from the hops.

I imagine the humidity or lack thereof would play a big part in evaporation % per hour.