Fuel Switching

Fuel switching is the operational changeover between fuels on the same voyage, most often from high-sulfur or 0.50 percent fuel to 0.10 percent distillate when a ship enters an emission control area under MARPOL Annex VI Regulation 14. The change of fuel oil must be completed before entering the ECA, with the date, time, position, and tank volumes logged, and the procedure managed to avoid thermal shock to fuel pumps and injectors from the viscosity and temperature gap between residual and distillate. Dual-fuel ships also switch between gas and liquid mode (LNG, methanol, ammonia, and the diesel pilot). Poorly managed switching risks loss of propulsion from fuel-pump seizure.