What do stewards do in brewing competitions? Do you need any experience to steward?
If you have a good comp director and experienced head steward then, no, you don't need any experience.
Basically your job is to do whatever you are told. Not to put too fine a point on it, but the stewards job is to supply whatever the judges need so they don't need to leave the table. The next sample, more blank score sheets, pencils that work, more water, more crackers etc. They may ask you to bring over the comp director or judge coordinator for a question involving the rules (should a beer be disqualified, is this beer mis-categorized etc etc). As they say for several different jobs and services, if no one notices you, you're doing your job perfectly!
Be careful though, stewarding tends to lead to judging!