The ferry is about 40 minutes. That said, Steves calls the travel from Sorrento onto the Amalfi Coast a "bungee jump of a bus ride," saying it "will leave your mouth open and your film exposed." ...
Travelers can also reach the Amalfi Coast by train. From Naples, you take can the Circumvesuviana train to Sorrento, Salerno or Vietri sul Mare, and then take a Sita bus to the nearest Amalfi town.