Imperial Stout Question

Planned brew for this weekend is Jamil's Russian Imperial Stout and I have a few quick questions.

1. How much water do I mash with? Since the recipe calls for a massive 23 pound grain bill how do I keep my wort down to seven gallons? Even at 1qt per pound that's 5.75 gallons just for mash. Assuming 1.5 gal. grain absorption I only have room for 2.75 gallons for Mash-Out and Sparge to hit 7 gallons of starting wort... Is this enough for an effective batch sparge considering raising to mash out will take at least a gal?

2. Fermentation, I assuming a long primary but how long exactly?

3. Yeast, will a one packet starter be enough for an anticipated 1.098 OG? (Wyeast 1056)

1. You are going to lose way more than 1.5 gallons to grain absorbtion. Depending on your system, it will be close to double that. I would go with somewhere aroung 1.25 qt/lb. Since you are batch sparging I would skip the mash out. Just vorlauf and drain after the mash. I would probably then go with one batch sparge with the rest of your water and it can be HOT. I would probably go at least 185* if not 190*. Remember, with this big of a beer your efficiency is going to suffer. I would figure about 65% efficiency, unless you want to refugure you water additions, and go for a long boil so you can add more sparge water.

2. With a beer this big, just let your hydrometer tell you when it is done fermenting. When it is done, rack it to secondary and let that puppy bulk age for a few months.

3. You are going to need a HUGE one pack/vial starter. Use this to guide you: Mr Malty Pitching Rate Calculator

You could use 2 packets of dry yeast or 3 if you really want to. I used one packet on a 1.060 beer so I would think two would be enough for yours.

I am planning on doing a large RIS and I planned on starting with extra pre-boil volume and boiling down to my normal pre-boil volume then starting my hop additions and boil for the normal hour.

As far as gravity & sparging, take the runnings as-is with a sparge to hit your volume, then parigyle that ****!

Thanks for the help guys,
Your right about the asorbtion double e, I forgot to consider that there is a ton of extra grain.
I also like the idea of skipping mash out coupled with getting a little extra volume and boiling down before adding hops. At 1.25 I can mash with seven gallons, lose three to absorbtion and batch sparge with almost 4 gallons.
I think I am going to hydrate and pitch 2-3 packets of S-05...?

2 packets will get the job done.

Spludge, how did this brew session turn out? I was planning on brewing the very same thing and was wondering if your RIS partigyle was done with this brew and if so, what kind of gravities and volumes you got for each batch.

From the chart in Designing Great Beers, you should expect to lose 5 gallons to absorption with 23 pounds of grain.

He says that the post-mash grain mass is 40% of the original mass, 60% is lost to sugars and proteins that are extracted. The total weight of the spent grain mass is 20% grain and 80% water. Starting with 23 pounds of grain you should expect to have 23 * 0.4 = 9.2 pounds left. That 9.2 pounds should be holding 9.2 * 4 = 36.8 pounds of water. Water weighs about 8 pounds / gallon so that's 36.8 / 8 = 4.6 gallons.

Danielinva,
I don't have any notes as I am home in Alaska for the summer but I may be able to help a little.
I would definitely do the partigyle if you are using a stove top as boiling down 12 gallons on an electric stove would take forever. If you have a turkey fryer then I would say go for the full on RIS. Mine was only at 1.092 so it was not as strong as I wanted it to be, due to the partigyle.
I believe I mashed with about 6 gallons and then sparged with four and came up with about 7 gallons. I the sparged again with around 5 gallons for the partigyle wort.
I haven't tasted either yet, the RIS is bulk aging back home right now and the partigyle has been in bottles for two weeks.
Happy Brewing

Here is a good link for the partigyle.

Linky