Another efficiency question

[Moody_Copperpot]

I got only 58% efficiency yesterday, the lowest to date. I have been from 65%-78%, depending on how big the beer was. Yesterday I did about 11lbs grain, so I used about 4 gallons of water to mash. I was running around doing stuff while I was mashing in my cooler MLT, so I think I may have accidentally been rushing. When I took my final temp reading from the mash before taking my first runnings, I was only at 148F.
I got about 3 gallons from there, and added 4 gallons of water at 194 (which brought me right to 170) to get seven gallons out of it.
I didn't properly heat my tun, I know that, I only threw in about a gallon of 131 degree water while I heated the strike.
At the end of the boil my OG should've been 1.054, but instead it was 1.042. Is the reason most likely my low mash temp?
I know I should've mashed longer, done a double batch sparge, and taken a pre boil OG reading, but I didn't. I did a single batch sparge right to the boil. This is my seventh batch AG, and I have never, ever had this low of an efficiency.
I know it could possibly be the crush of the grain too, and I really need to invest in my own mill.

 

[Moody_Copperpot]

Maybe I just answered my own question. I just found this and this answers A LOT! I have been just adding enough sparge water to bring it to 7 gallons. I watched this youtube video about brewing, and the guy had 8 gallons going, and I remember wondering why he would bother using such a high volume for his boil…now it makes sense.

I've seen a lot of threads started concerning problems with peoples first all grain brews.
I would like to give a couple suggestions that might help improve the process for new AG brewers. Here are a couple common problems I've seen:

1. Low efficiency.
I have found that the most common thread here is not using enough water during mashing and sparging. All you need to do is figure 1 to 1 1/4 quarts of water per pound of grain for the mash and about 1/2 gallon of water per pound of grain for sparging.
I think some folks are concerned about too much wort volume when they are figuring how much water to use but if you want decent efficiency you have to use the correct amount of water.
If your brew pot isn't big enough for the volume required you will need to compensate by using more grain and know that your efficiency will be lower. (You will want to use the 1 to 1 1/4 quart per pound of grain for the mash and adjust your sparge water for the volume required)