Types of marine engines

Jul 11, 2022

The larger a ship is, the greater the size and weight of its engine, so it is not advisable to install it at one end of the hull. For this and other reasons, there are two main types of marine engines: outboard and inboard. Fuel consumption does not usually vary significantly from one type of engine to another. In addition, the revisions that have to be made to each type of engine are similar. However, there are also quite a few differences between types of marine engines.

Outboard marine engines

Small boats (less than 8 meters approx.) usually use outboard motors that are placed at the stern. Although there are small boats that use inboard engines. There are engines from 2.5 hp to more than 350 hp. The same boat can have more than one outboard motor, and there are gasoline, diesel and electric motors.

The outboard motor has a number of advantages:

  • Easy maintenance
  • Easy installation and disassembly
  • When the boat is moored, the motor can be raised above the water for maintenance purposes
  • In areas with shallow water or floating nets the motor can be raised to avoid problems
  • No need for a rudder
  • Quieter
  • Cheaper

But, it also has its disadvantages:

  • It may heat up or catch fire more easily
  • It is easier to wear out
  • Generally, it has less power
  • There is more risk of cavitation
  • It can unbalance the boat
  • It breaks the external aesthetics of the boat

There are two types of outboard motors:

  • 2-stroke: it is lighter and easier to install, but more polluting
  • 4-stroke: heavier and more expensive, but quieter and more environmentally friendly

Inboard marine engines

For larger boats (more than 8 meters approx.) inboard engines are usually used, which are located inboard. Like outboard engines, inboard engines can also be gasoline, diesel and electric.

The inboard engine has a number of advantages:

  • Most are diesel, which last longer and are safer than gasoline engines
  • It consumes less than an outboard motor
  • As it is installed in the lower part of the hull (lower gravity point), it provides more stability
  • As it is inside the boat, it does not break the external aesthetics and there is more space at the stern
  • The propeller is deeper and there is less risk of cavitation

But, it also has its disadvantages:

  • Repairs usually have to be done on board
  • It weighs more and takes up more space
  • It is more expensive

Inboard-outboard marine engines

In addition to the above-mentioned marine engines, there are inboard-outboard engines, also called Z-Drive, which combine the advantages of an inboard and an outboard engine. The engine body is installed inside the boat and the transmission is installed outside as in an outboard engine.

The advantages of an inboard-outboard engine are:

  • It has more power than an outboard
  • The engine is hidden under the boat
  • No rudder is needed

 

At Máquinas Marinas MAQMAR we are specialized in inboard marine engines, more suitable for large boats or ships. For more information, please contact us.