Good afternoon Allan:
As Doug states, leaving the side door closed and closing all of your vents (top and bottom) will ultimately suffocate the coals. I say ultimately because the WSM is so well engineered for heating and cooking that, like you home oven, it likewise has a fairly long cool-down period. I've found that you can do yourself a favor (especially when it comes time to clean the water bowl )and somewhat reduce this time by pouring more water into your water bowl. Outside of that, just kick back, enjoy your delicious smoked meal and drink a few more beers while nature takes its course! Good luck.
?.John
