I usually brew 5 gallons at a time using my basic kitchen setup (5G Igloo cooler, 30 qt gas/electric kettle, immersion chiller). Recently I needed to brew 11 gallons of beer without the time to do two completely separate brews. I was also going to be splitting in to two 6.5G fermenting buckets for a yeast experiment, so I wanted the wort to be as similar as possible. How to accomplish this?
Basically I took a page out of the Partial Mash brewer's book and did the whole thing as a PM. Scaled the base recipe back to 9# of grain and used DME to bump the SG back up to where I wanted it. Did my usual mash in the cooler, ran-off into the kettle, and added the DME. Boiled what I could (6.5G down to 5.5G), calculating the hops with concentrated boil efficiency. Cooled it down a bit after the boil and splash strained into one of the buckets. Siphoned about half into the other bucket and topped both off to 5.5G (a little tight, but I know this is a yeast that doesn't throw much krausen). Pitched the two yeasts and called it two beers.
It's just a scaled up version of what a PMer would do with 4.5# of grain and a 3G boil kettle. You make do with what you can and compensate for the rest. I hadn't done it before and it has opened my eyes to the possibility of brewing more with very little additional effort. Actually a little less as I didn't have to cool the wort all the way to pitching temp, just to 150 or so. The cold topping liquor took care of the rest. Hit a SG of 1.032 and 70'F in 5 hours.
Has anyone else had this epiphany? If so, what else do you take into account? Does anyone else know what a blivet is?