Marine engines are machines that propel a ship or a boat. Rotax marine engines include 2- and 4-stroke engines in 2- and 3-cylinder inline configurations. These engines cover a range from 130 to 255 hp (97 to 190 kW). However, different types of marine engines include marine steam engine, petrol or gasoline engine and diesel engine. Today, the choice of marine engine is wider than before. Moreover, all the specifications are now available from the manufacturers on the Internet, and there also are some useful independent side-by-side comparisons. Read on to know more about Rotax marine engines and its types.
2-stroke marine engines are basically used on motor boats and personal watercraft (PWCs). In simple words, the two-cycle engine has been the mainstay for outboard engines. In these rotax marine engines, the intake and exhaust ports are both open during the piston's down-stroke, which allows some fuel to pass straight through without being burned. The biggest advantage of the two-cycle engine is that it is very lightweight. The horsepower to weight ratio is the highest in marine reciprocating engines. 4 stroke marine engines range all the way from lightweight 2 horsepower (HP) portable models, to 350 HP monsters bolted directly to the transom (stern of the boat) or to a bracket that is then bolted to the stern.
4- Stroke rotax marine engine is a self-contained unit; it consists of a power head, the intermediate housing (the drive shaft) and the lower unit (gear, housing and propeller). The throttle, gearshift and steering are attached to the power head. To change the direction of a boat using an outboard 4 stroke motor, the entire unit – power head, intermediate housing and lower unit – swivels, thus changing the direction of the propeller thrust. These 4- stroke marine engines are very lightweight for the HP that they produce, and because they are located “outboard”, they take up little or none of the boat’s interior volume.
In diesel marine engines, only air is introduced into the cylinder head. These rotax marine engines are basically used in mid-sized cruisers, trawlers, large yachts, work boats and commercial vessels. However, the air is compressed to about 600 pounds per square inch (psi), as compared to about 200 psi in the gasoline engine. These marine engines burn considerably less fuel than a gasoline engine doing the same work. They have no ignition system to attend to. Moreover, they can deliver much more of its rated horsepower on a continuous basis than can a gasoline engine. The life of a diesel engine is generally longer than a gasoline engine. However, getting familiar with the kinds of marine engines will help you to gain more knowledge about these engines.