I normally have a lot of headspace in my cooler for average beers. If I pre-heat and cover the mash with a sheet of aluminum foil I lose no more than 1 degree during the mash.
Primary: Pineapple Heffeweizen
On Tap: Simcoe/Amarillo IPA, Centennial Blonde
Bottled: Milk Stout(bronze and gold medals), Spiced Punkin Ale, White House Honey Porter (ag), Mango Wine, Gerwurztraminer
"If wrong feels so good I don't wanna be right."