Regardless of the amount, I cook them for 25 minutes after good steam starts coming out from underneath the lid. If you are in doubt, or to calibrate your cooking time, check crabs in the center of the pot with an instant read thermometer. Yeah, wear gloves. Stick it into the center of the crab through the shell. Crabs need to be cooked to more than 160 degrees for at least one minute to kill bacteria. They turn red after just a couple of minutes, so never use color as an indication of doneness (like they say on the Old Bay can.)
Doc
