It is rather common practice for the marine industry to use water heating coils to heat heavy fuel oil. Obviously, the efficiency of the heat transfer process is strongly dependent on the dimensions of the coil (length, thickness, and diameter) as well as on the operational parameters (oil temperature, steam temperature, and steam pressure). In the present work, the heat transfer from superheated water at high temperature (apprx. 424 K) and fixed pressure (5 bar) to fuel oil tanks of specific dimensions was theoretically investigated by both a macroscopic thermo-dynamical approach and microscopic simulations (using the commercial CFD-ACE+ software package). Since the scope of this study was to estimate the necessary size and length under the assumption of an insulated tank, a parametric analysis was also performed in order to identify the relative influence of each parameter on the process performance.