Hi. I always do a variety of calculations on brew day. A buddy told me that for a batch ending with 6 gal after the boil (8 pre-boil) and up to 14# of grain, he always strikes 4 gallons. He figures absorption at about .3gal/# and goes from there. Do any of you get really specific or just strike a set amount. I'm guessing I'm making it a little more complicated than it needs to be.
I usually estimate about 1 quart per pound of absorption, but I imagine it would depend on the grain, the grind, your brewhouse setup, etc. I usually strike to get close to my collection volume (26 quarts) and add a little extra if necessary. This is a little easier for me because my brew kettle is graduated, so I know how much wort I've got in there. Do you have the same, or are you relying on your strike volume to know whether you've hit 8 gallons collected?
Striking with a constant amount of water regardless of how much grain you're using seems like a lazy way of doing things to me. Personally I generally strike with 1.25-1.33 qts of water per lb of grain, and on my system lose about a pint per lb to absorption. Losing a qt per lb to absorption sounds like a lot, if you're brewing with 12 lbs of grain that would mean losing 3 gallons of water, and I don't really see how that's possible unless you have a ton of dead space in your mash tun.
Adding the strike water that way would seem to me to also make it much more difficult to attain a consistent mash temperature... Mind you if you are used to it, you're used to it.
Most brewing calcutator sites or software are fairly consistent. Enter your water-grain ration, grain temp, wort volume, mash temp etc, and you will get what you want. That said... After enough batches I have learned to wing it. Keeping in mind that withing reason, your water-to-grain ratio is quite flexible, I'll dump in ~4-5 gallons (using educated guesses based on the situation) of 165f-170f water, measure temp quickly, and adjust with cold or hot water accordingly. No worries.
