The RTA have announced service timings for the various means of public transport including the Dubai Ferry, for the holiday of Isra W’al Miraj on 23rd April 2017.
The timings announced by the RTA show that there are no changes to the services that run every day on the ferry.
You can find full details on all of the ferry services here.
They have also announced that public parking in the Emirate will be free on that day (apart from the Fish Market parking and multi storey parking).