Analysis of calculation methods for the towing resistance of mobile platforms at sea

Under standard sea conditions, to accurately predict the towing resistance of a mobile offshore drilling unit MODU（Mobile Offshore Drilling Units） without a particularly large wind area, a calculation method is proposed for situations where the empirical formula from the CCS ＜Guideline to Towing at Sea＞ is not applicable. The total resistance in the theoretical calculation is the sum of wind resistance, flow resistance, and wave resistance. The wave resistance is calculated using CFD（Computational Fluid Dynamics） software, the results of the CFD method indicate that wave resistance constitutes the main portion of the towing resistance. Further study reveals that wave resistance decreases with increasing wave period and increases with wave height. As the wave period increases, the rate of increase in wave resistance diminishes with higher wave heights. To ensure the safety of towing operations for MODUs without a particularly large wind area at sea, operators should pay attention to both wave height and wave period in addition to wind speed.