Evaluation Study on Ship-to-Ship Loading/Offloading Safety Operation by Numerical Fluid Dynamics Method Rudi Walujo Prastianto 1* , Fahmy Ardhiansyah 2 , Eko Budi Djatmiko 1 , Murdjito Murdjito 1 , {rudiwp@oe.its.ac.id} 1 Ocean Engineering Department, Insitut Teknologi Sepuluh Nopember, Surabaya, Indonesia 2 Doctoral Student in Ocean Engineering Department, Insitut Teknologi Sepuluh Nopember, Surabaya, Indonesia Abstract. The demand of energy from our society is rapidly increased year on year linear to the world economic growth. Ocean gives great energy potential resources to fulfill energy need. For instance, oil and gas exploitation activities in offshore field had been established for a long time. Thus, such kind of operation should be improved in manner of safety to achieved global economy goal for a cleaner, safer, and sustain of the ocean. One of the process during oil and gas exploitation is cargo loading and offloading from ship- to-ship. Due to consider as dangerous goods, oil and gas cargo transfer process is obligated to fulfill several safety criteria. A ship-to-ship configuration has more complex hydrodynamic-induced motion behavior than the single ship. Due to its complexity, a proper evaluation study is needed to evaluate a safety of the ship-to-ship operation. This simulation study is performed by Numerical Fluid Dynamic method in ideal fluid approach. In order to observe the complex hydrodynamic behavior, incident random wave is applied to side-by-side ships in different configuration by considering three mains steps during ship-to-ship operation i.e. berthing, moored, and un-berthing scenario. Criteria had been being evaluated are ships clearances, relative motion between ships, ships roll motion, forces acting on ships and tug boat, mooring lines loads and fenders deflection. Not only internal factor from the ships evaluated as safety criteria but also the external factor is evaluated. The external factor considered from weather are wind speed and wave height limitation. Keywords: Ship to Ship, Safety Operation Criteria, Fluid Dynamics, Ships Interaction 1 Introduction Oil and gas is remain one of the proven solution in present energy need. The exploitation of this resource usually conduct in onshore and offshore site with each site have their challenging situations. When exploitation is conduct in offshore, the operation will face a condition that environment is going to harsh during storm weather. Therefore, the exploitation facilities should be able to withstand during its operation. Oil and gas offshore field are either located in shallow water or deep water depend on number of this resource beneath ocean seabed. In deep water, exploitation facilities is utilize floating structure due to its feasibility compare to fixed structure. Fixed structure is technically and economically feasible to install in shallow water up to mid water depth, for instance the deep water is not more than 100m. Oil and Gas ICSEDTI 2022, October 11-13, Tanjungpinang, Indonesia Copyright © 2023 EAI DOI 10.4108/eai.11-10-2022.2326333