Is a half shirt appropiate for a 14 year old to wear in public?

Whether you are or not, it'll look trashy. I know what kind of shirts you're talking about, and those shirts are USUALLY worn with a tank top underneath. Unless you have a completely nice toned stomach with a bit of abs...then yeah, go for it. (; If not though, no one really wants to see that...sorry. I say you take a tank top though. The beach might be fine though, if it's to put it over a bathing suit/bikini.