There are 3 free ferry connections that bring you to Amsterdam North from the back side of the Central Station, to the other side of the IJ.
They go 365 days per year.
You can bring your bicycle or moped (also for free).
The one to Buiksloterweg is the busiest one, and the only one that goes day and night. During rush hour this ferry connection is served with 3 boats. The Buiksloterweg ferry is the one you need to take to the EYE Filminstituut or Tolhuistuin.
On this page is a list of all three.
Ferry across the IJ, to Amsterdam North
Tasmanstraat ferry terminal
Oostveer (ferry from Azartplein to Amsterdam North)