Help with dilluting an 8 gallon high gravity into (3) 4 gallon batches

[Paxton]

I am trying to brew one batch of beer and separate the batches into (3) 4 gallon fermentations. I'm hoping I fan boil down 9 gallons in a 10 gallon pot down to 7-8 gallons, cool and distribute them evenly into 3 fermenters, then top them each off to make 4 gallons a piece. I don't have time to brew three separate batches and this is for a 4th of July party so it needs to be done asap. Is that too much dillution? Is their any other advice for pulling this off? I'm usong 21lbs of grain in a 10 gallon mash tun and have 6 lbs of lme also. Thanks everyone!

 

[brewkinger]

List the ingredients and I will see what I can do in Beersmith.
It is a fairly simple calculation though.
Assume an OG of 1.090, then multiply the 90 gravity points by the total volume of 8 gallons.
That is 720 points.
Now add in 4 gallons of water and you will have
720 points divided by 12 gallons.
You now have a 1.060 beer which can be split into 3- 4gal batches.

 

[madscientist451]

It seems too complicated to me. Instead of three batches 4 gallons each, just make a normal beer with the pot you have so it would be two 4 gallon batches. You want the beer by July 4th so better quit fooling around and get brewing. It would be better to have 8 gallons of beer that you can expect to be good than to have 12 gallons of questionable brew. If you really need the extra 4 gallons, get some LME and some crystal malt and make a 15 min beer, the recipe and process can be found here on HBT.