Help on double checking my math (11 gal big beer)

So I want to make 11 gal of Stone Bitter Chocolate Oatmeal Stout for my birthday in a few weeks here. I just want to make sure that everything is going to fit.

70 qt Coleman extreme = 17.5 gal of total space

40 lbs of grain absorbs 5 gal at .125 gal/lb

If i mash in 11.5 gal of water this will yield 6.5 gal of first runoff.

6 gal sparge water will get me to 12.5 preboil for a 90 min boil yields 11 gal in my keggle.

11.5 gal of mash water and 40 lbs of grain take up 14.7 gal of space per “Can I Mash It” at 1.15 lb/gal.

14.7 gal fits into 17.5 gal of space unless I am crazy.

This should work right? Am I missing something?

Also the recipe calls for 8 oz Cacao Nibs in the boil. I brewed this before and it was good but besides just increasing the amount does anyone have any other advice for a bigger more chocolatey flavor?

I think youll be alright. For reference, I did a IS (10G) with 35# of grain in a 60qt cooler, I think I mashed at 1.15 too…it was a tight fit, but it worked

Here’s a link to a calculator regarding how much you can place into your mash tun. I am not vouching for its accuracy as I have not used it.

http://www.rackers.org/calcs.shtml

Your plan is spot on. I’d maybe bump up the mash ratio just to make it easier to stir things up. Maybe go with 12.5gal of mash water.

As for chocolate flavor, some pale chocolate malt works well for that. And depending on how well toasted your nibs are, you might toast them a little more in the oven.