I've done 5 all-grain batches and everything is going perfectly well (especially the beer!) except for one thing - VOLUME. I seem to be having a really hard time calculating anything. My first brew was fine, and I calculated about a 25% boiloff rate. Then, my second brew I used the same info for mash tun loss, grain soakage, boil-off rate, etc and ended up with about 6.25 gallons of wort in the fermenter (was going for 5.5). Then, on my next beer i ended up with 4 gallons of wort in the fermenter. I'm so frustrated. But the worst is the most recent - I measured 7.75 gallons of wort pre-boil. My boil time was 60 minutes. I ended up with 4.25 gallons in the primary, MAYBE 4.5. What could it possibly be? That's 2.5 (or more) gallons lost in 60 minutes! i guess i'm leaving about .25-.5 galons of trub in the kettle... but that's still a 2-gallon per hour + boil-off rate. And remember, i had one beer that ended up 3 quarts too much (which is much less of a problem . My kettle is pretty wide i guess, and my boils are not insanely vigorous. It just seems like I have a huge variation in boil-off rate. HELP i'm so pissed off.