The RTA has announced the timings for marine transport during the occasion of Eid Al Fitr as follows:

For the Dubai Ferry it appears that the timings are reverting to standard operating hours – see here for more info.  The timings shown above are for Friday to Sunday for Al Ghubaiba to Sharjah and vice versa.

The trip from Al Ghubaiba to Dubai Marina appears to have been missed from this graphic but as it shows the ferry going from Bluewaters to the Marina we assume that this is also working on standard operating hours.