No, it is not necessary to confirm the departure time of your ferry, as it is uncommon for ferry schedules to change.
If there is a schedule change that affects your trip, Ferryhopper will notify you immediately via email or SMS, as soon as we are notified from the ferry operator. We thus recommend that you check your email once on the day before your departure and once on the day of your ferry trip. Most ferry companies also inform their passengers directly via text message in case of schedule modifications (given that you provided the correct contact information). You can also contact the local port authority on the day of your trip to get the latest information on schedule changes and delays.