That's the problem ;-)

Right now, for example, if you take the 13.13 Tram 4 (at 13.16 Schiffbau), then 13.19 S16 to the airport (at 13.29) it takes you 16min "door to door".

Obviously, with luggage and being no local, you won't make that "Turnschuhverbindung" as it's called in Switzerland (tight connection) but it's much closer as 30min would sound..

By the way, when did you happen to be there? The area around Schiffbau is heavily "party-oriented", ie on the evenings Thursday-Saturday, there is a lot of stuff going on (and it's office area too, so Mo-Fr during work hours also quite some people) but on Sunday (and Saturday morning-afternoon) it's pretty dead.