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Diesel fuel is the most commonly used fuel in marine engines due to its efficiency, energy density, and availability. Marine diesel engines offer a robust power-to-weight ratio, making them suitable for a wide range of vessels, from large cargo ships to smaller recreational boats. Diesel fuel provides a high level of performance and is less volatile than gasoline, which enhances safety in a marine environment.

Another reason for the widespread use of diesel in marine applications is its ability to operate efficiently at varying loads, which is crucial for the operational versatility required for different types of maritime activities. Moreover, diesel engines generally have a longer operational life compared to engines using other types of fuel.

While heavy fuel oil is also utilized in larger vessels for economical reasons, it requires additional handling and treatment due to its viscosity and impurities. Natural gas and kerosene are less common for marine applications mainly because they either lack the needed energy density for large ships or present handling and performance challenges that make them less favorable compared to diesel. Thus, diesel fuel remains the standard choice for powering marine engines.