How many compression rings in marine engines normally have?

Can anyone explain if there is a difference in construction between marine diesel and truck diesel engines?

• It seems that the fuel type in the marine diesels is a heavier type fuel. In marine diesel engines of smaller caliber, below 400 hp, are the engines the same as in diesel trucks of the same horsepower?

• Answer:

  They are the same basic engine, but they have been marinized for marine use. This could mean a heat exchanger instead of a radiator, and a raw water pump to use sea water for cooling. The exhaust system typically uses that raw water for cooling and then dumps it overboard out the exhaust pipe. The marine gear has an oil cooler for its fluid. Different injectors may be used for better power characteristics. If you get a chance to look around you can find one basic engine in many forms. For example I used to drive a payloader at work. It had a Cummins 4B engine in it. My current boat has 2 Cummins 4B engines in it, they are the same block fitted with marine systems.