Engines In Superyachts – How Do They Work?

JAN 11, 2022 AT 03:19 AM

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Superyachts are luxurious pleasure vessels that are built to bring joy. There is no definition of what kind of yacht you can call a superyacht. We believe that if the vessel is privately owned, and it’s more than 130 feet or 40 meters long, it can be called a superyacht.

Today we’ll focus on the engines that power these marvelous machines. You may know that the majority of huge yachts use marine diesel engines, and now shipyards also tend to build hybrid superyachts with the diesel-electric propulsion system. Let’s look at the engine types and the way they work in modern superyachts!

Why marine diesel engines?

Marine diesel engines are very popular superyacht power units because they are more efficient and easier to maintain than other types. The reason why big yachts use them is that the diesel engine has high thermal efficiency.

Also, these engines are very powerful and reliable. You can power superyachts with up to 100 tons of weight, and the engines are designed to last for 10-15 years or even more if properly maintained.

Superyachts are huge machines. For example, the world’s largest yacht Azzam which was built by the Lurssen shipyard is 180 meters or 590 feet long. So you will need a couple of really big engines to make it move on the water with decent speed.

A superyacht needs powerful and reliable engines to drive all those systems and achieve high top speeds at the same time. Which engine type can fulfill this task? The answer is marine diesel engines. These engines are the industry standard for big yachts, but now they can also be coupled with electric engines and generators forming hybrid propulsion systems.

How do hybrid marine engine plants work?

Many modern yachts use hybrid propulsion systems to increase fuel efficiency and reduce emissions.

The superyacht engines can be paired with electric generators or other devices to produce electricity to power the vessels. Sometimes the electric engines can be powered by additional batteries that are recharged by solar panels making the fuel efficiency even better. 

Why are there usually two engines on a superyacht?

Big yachts usually use two engines because of better maneuverability and redundancy.  Two engines are more efficient than one unit because they have symmetric power output, while each engine can also be used if the other fails.

Also, superyachts usually have propellers on both sides to facilitate a turning motion or tacking at larger angles without having to use the engine. This gives captains better control over their vessels and allows them to speed up or slow down very quickly.

Kinds of engines used for big private vessels

The biggest yachts in the world usually have MTU or Wartsila marine diesel engines. These superyacht power plants are designed for high-speed cruising and long journeys. 

The engines usually use common rail technology with low-pressure fuel injection pumps.

This kind of engine allows for very precise control over the amount of fuel injected into the cylinders.  It’s a bit like controlling a supercharger on a car. They also have better reliability because they don’t rely on mechanical components when injecting the fuel.

Diesel engines for superyachts are usually operating in around the 5000 RPM range which means they can run at high speed for a long time. 

There are unusual concepts like nuclear-powered superyachts or jet-engine vessels, but marine diesel engines are still the most popular on the market.

What should be the power of a superyacht?

Usually, the yachts have the power of 4000-8000 horsepower. Super large yachts may have over 15 000 horsepower engines, but don't forget about hybrid superyachts which use smaller diesel units and electric engines. The combined power of such plants is still very high.

Luxury private vessels tend to have the largest engines available to achieve high speeds. The superyachts can go up to 40 knots. The vessels of this kind usually have powerful engines for cruising in comfort.

Fuel consumption - how much marine diesel do you need?

Large superyachts like Octopus or Azzam burn around 400-1000 liters of fuel per hour.

Medium superyachts like Oyster or Maltese Falcon burn around 150-300 liters per hour, and small superyachts like Turquoise use around 30-50 liters of marine diesel per hour.

Superyachts are usually able to travel between 2 000-5 000 miles on one full tank of fuel according to the vessel size and its power. But again, there is a plus side - superyachts with hybrid propulsion systems are much more efficient. So, smaller superyachts with efficient hybrid power plants can cruise more than 10 000 miles on one tank of fuel.

Superyacht engines - the most expensive parts of vessels?

Even though superyacht engines are quite big, they are not the most expensive part of the yachts. The design and materials that go into building superluxury yachts are far more expensive.

Say, a 12V MTU engine that is appropriate for powering a middle-sized yacht costs around $500 000 for the plant of two units. But engines that range from 5000 to 15 000 horsepower can cost over $3 million to install.