The city authorities said the operating licence would cost EUR 10.3 million.
The Galeb (Seagull) is a protected cultural property of the Republic of Croatia.
The concession-holder is expected to ensure on the vessel space for a 507-square-metre museum, a recreation centre, hostel and hotel rooms, a restaurant, a congress centre and a bar.
Work on making the ship commercially usable is to be done by the concession-holder without the possibility of a refund.
Work will have to be carried out in line with conditions defined by a local conservation department and will have to be approved by the city authorities.
The invitation for bids is open until March 24.