Here are the specifics of the mash....
Started with the recipe as described, no modifications...
Preheated mash tun (converted recatangular cooler w/ 12" Midwest Supplies screen) with 1 gallon of 180 degree water.
While that sat, I heated 4.5 gallons of water to 165 degrees and added to the tun.
Added 14.5 lbs of grain, mash temp settled at 153-154. Vorlaufed
First batch/drain/sparge was 3.75-4 gallons @ 1.061 OG.
Heated another 4.5 gallons to 175 and added back to tun. Stirred for several minutes.
Vorlaufed again... Drained off an additional 5.25 gallons @ 1.022 OG.
Boiled the 9.25 down to 6.5 gallons over 90 minutes to OG of 1.061.
My question is. For a first time batch, how did I fare. I know the recipe estimated a OG of 1.066. 1.061 "seems" efficient to me & I assume that had I boiled it down to 5.5 gal, MAYBE the OG would have been even closer??
6.5 seemed fine to me at the time as it will allow me to bottle a gallon in addition to what I will keg.
Thanks again!
Couple different things going on here. Lets take it a step at a time.
If you were aiming for 5.5 gallons, you're a bit off. But that doesn't mean that the beer is either better or worse off. You just have more liquid than you expected.
Assuming you used the same amounts of grain as in the recipe, lets see how you did. The recipe is 5.5 gallons of 1.066, which works out to 330 gravity points (5.5 x 66). You came out with 6.5 gallons of 1.061, which is 396.5 points (6.5 * 61). This tells us that your mash is more efficient than the OP's is.
How efficient was your mash?
Through a lot of math (or by just adding the ingredients to BeerSmith), we can tell that we have about 486.5 gravity points of potential here. With your 396.5 gravity points, your mash is 81.5% efficient. That's right about where you should be at this gravity IMO. The OP is 69.2% efficient, which I feel's little on the low side.
What's the point?
If you measured your gravity after the last rinse, you would have seen you had 9.25 gal of 1.043 (again, 396.5 pts). To boil down to 1.066, you needed to boil until you had 6.00 gal left. We know your boiloff rate from above is 1.83 gal/hr, so that means that you should have boiled for 1.77 hrs (1 hr, 46 min) total. Thus, you should have started your 60 minute boil timer when the liquid level was at 7.83 gal mark (approximately 46 minutes after reaching boil).
Or, we can go the other direction. If you knew your tun deadspace, grain absorption ratio, and average efficiency, BeerSmith could have scaled the grain amounts down for you so that you ended up with the 330 gravity points. That way, when your mash naturally varied by a few percent, you could correct and the difference would be in the ballpark of +/- 0.2 gal.