Partigyle Help

Hi all, I'm planning on attempting my first partigyle brew this Sunday. An imperial IPA and a session IPA. I've done some reading in Gordon Strongs book, but am having trouble setting up the recipe. I'm using iBrewMaster, if that helps.
1) how do I figure out how much water for the first mash? I have 20.25lb of grain and need to get about 7.75gal preboil volume.
2) how do I figure out the specifics for the second batch? I'm assuming I don't need to compensate for grain absorption anymore, correct? Also how do I know what the OG should be? Do I just go in blind?
3) for the second running, do I do it at normal mash temps or at sparge temps?
Thanks in advance!

1. If you are just using first runnings for the big beer than enough to account for your boil volume plus grain absorption.
2. Use the spreadsheet in the link below.
3. Just sparge.


http://braukaiser.com/wiki/index.php/Batch_Sparge_and_Party_Gyle_Simulator

Thanks, ill check that out.

I have a direct fire HERMS system. So would it be better to do the first mash and raise to mash out temps then drain? Or drain at mash temps and add the second runnings to bring the grain bed up to 168-170?
I'm just curious if mashing out will take too much of the sugars away for the second batch. Thoughts?

Assuming you're brewing in the traditional fashion, there was originally no such thing as mash out, or, really, any way to raise the temp to mash out.

That said, I guess it would depend on how big you want your strong beer vice your session beer, since your mash out will remove starches that would otherwise be available for your session.