Old Bay Shrimp Boil

This is from the Old Bay website. I make it for summer parties because it is so easy and everyone loves it. The recipe as written makes 8 large servings.

Old Bay Shrimp Boil

4 quarts water, 16 cups
1 can (12 ounces) beer, I use Sam Adams
1/2 cup Old Bay Seasoning
2 tablespoons salt
8 medium red potatoes, quartered
2 large onions, cut into wedges
2 pounds smoked sausage, cut into 2-inch pieces
8 ears fresh corn, shucked and halved crosswise
4 pounds unpeeled jumbo shrimp, 21 to 25 count
1 stick unsalted butter, sliced

Bring water, beer, Old Bay seasoning and salt to boil in 12-quart stockpot on high heat. Add potatoes and onions. Cook 8 minutes. Add smoked sausage. Cook 5 minutes. Add corn. Cook 7 minutes.
Stir in shrimp. Cook 4 minutes or just until shrimp turn pink.
Drain cooking liquid. Place butter slices into a large serving bowl. Pour contents of pot into bowl. Sprinkle with additional Old Bay, if desired.