Place about 6 cups of water, the vinegar, and the beer in an 8-gallon stockpot fitted with a raised rack. If you don't have a raised rack, use bricks wrapped in clean cloth to raise your rack about 6 inches off the bottom. It is important that the crabs not get wet while they're being steamed.
Make a layer of crabs on the rack, and cover them with 1/8 to 3/4-inch of crab seasoning. Bring the liquid to a boil. Once the steam starts to rise through the crabs, cover pot with lid, and steam for 30 to 40 minutes, or until the crabs are bright red. Remove the crabs with tongs or rubber gloves. (Using rubber gloves makes handling easier, preventing you from burning your hands—and inadvertently dropping any crabs.)
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