Why 2-stroke Engines are Used More commonly than 4-stroke on Ships?
Both 2 stroke and 4 stroke engines are widely available in the market but for a large ocean-going merchant vessel, a 2 stroke engine is more commonly used as the main engine and has a much better market.
Even with a wide variety of advantages that 4 stroke engine offers like the compact size of the plant, much more RPM or speed etc, a 2 stroke engine outshines with few but vital advantages.
Fuel Selection: The fuel prices have gone sky high and better grade fuel is adding higher costs to vessel operation. A two-stroke engine can burn low-grade fuel oil and hence reduce the running cost of the ship.
Efficiency: The thermal and engine efficiency of 2 stroke engine is much better than that of a 4 stroke engine.
Power: Most of the 2 stroke engines are now large stroke engines that produce more power. Hence they have high power to weight ratio as compared to 4 stroke engines.
More Cargo: Ship can carry more weight and hence more cargo with 2 stroke engines because of high power to weight ratio.
Reliability: Two stroke engines are more reliable in operation as compare to 4 stroke engines.
Less Maintenance: The maintenance requirement of the two-stroke engine is much lesser than 4 stroke engine.
Direction control: Direct starting and reversing are easier with two stroke engine.
No reduction attachments: As two stroke engines are low-speed engines, there is no requirement of reduction gear or speed reduction arrangement as required for high-speed four-stroke engines.