Two big beers in one brew session

How big a grain bill can your mash tun handle? I used to brew an all grain RIS (OG 1.120)with 42 pounds of malt. That filled my keg tun to the top and made sparging very difficult. The last time I brewed it I did 2 things differently. I cut the grain bill down to around 38 pounds and got enough improvement in efficiency to make up for the reduced grain amount, and I broke out my old ZapPap to mash about 10 pounds of the malt. It all went into my keg kettle and I boiled 15 gallons of wort down to 11 gallons. To do what you're talking about is fairly simple-you can just steep the some specialty grains in a separate pot and add that to the BW kettle, or dark grains for the RIS

 

You could potentially do a Belgian Triple or Strong Golden Ale and a Double IPA with this technique with the same grain bill (pils/American 2-row combination + a small amount of specialty grain). After a 60-90 minute boil with a bittering charge appropriate for the Belgian, you could then hop burst for the IIPA.

 

I did a 5 gallon partygyle batch on NHD. 25 lbs 2 row, 1lb of C60. Pre boil OG was like 1.087 and we boiled for about 120 minutes and it brought us to 1.100 for the actual OG. Depending on how big you want your DIPA to be I would maybe dilute your DIPA kettle and let the Barleywine kettle ride and be a big ass beer.

On a side note we did a second beer off the second runnings which clocked in at OG 1.047, capped the mash with 5 lbs 2 row and a lb of rye while those two were boiling and got a 1.040 OG on our last beer. We did an amber lager for our second beer so you could probably do a Barleywine and a Doppelbock type beer if you wanted two more different beers.

 

We usually brew an 18 gallon big beer and a 6 gallon big or small at the same time, with 2 mash tuns. Since you mentioned the use of a second kettle, why not invest in a cheap 2nd mash tun? It may be easier and you could have 2 distinct beers.
Just a thought.

 

Last time my buddies & I did this (brewed an imp porter w/port oak chips and a rose IPA) we combined the second runnings of both and used the leftover hops to make a kickass random small beer. If you have the extra space/yeast/bottles you might as well do it, it's like getting another batch for free.

 

I vote 10 gallons of Barleywine!

Anyway, I am not so sure about IIPA/Barleywine. Mainly because of two different desired fermentabilites, unless you plan on adding simple sugar as part of the IIPA fermentables. You can forget about melanoidins in a full boil at wort pH too.

Barleywine/ RIS could work with a separate minimash for the roasted grains.

I have done a Belgian split before adding the sugar to the fermenters, one dark and one light. That way you do not have to move wort in the middle of the boil.

On moving the wort halfway, I assume you have pumps and other cool stuff. Otherwise, that sounds a bit risky. Might be better to start off using both kettles.

Speaking of starting off with both kettles, you could boil down some first runnings for the Barleywine. That way the gravity of the IIPA wort is reduced and you sort of skirt around the fermentability issue.

 

I kind of like the idea of barleywine/IIPA. Bigfoot ale comes to mind, as it's pretty "IIPA like" when fresh (even kind of when aged), and I'd think you could find a IIPA recipe that was quite far along towards barleywine territory. However, I also like the idea of a second mini-mash of some extra ingredients for the barleywine (maybe some more base malt, some more crystal malt, and/or some more [insert your fav BW ingredient here].

Some of the other suggestions are quite good too.

Let us know what your final plan is!