Big Boat Engine Options: Powering Your Voyage

Choosing the right engine for a big boat is a complex task. There are many factors to consider, such as the boat's size, weight, and intended use. The engine's power, fuel efficiency, and environmental impact are also important considerations. For example, a large engine like the Wärtsilä RT-flex96C, a turbocharged two-stroke reciprocating diesel engine, may be suitable for a very large container ship but would be unnecessary for a smaller vessel. Additionally, with rising fuel costs and environmental concerns, alternative fuels and propulsion systems are gaining popularity, such as liquefied natural gas (LNG) engines and electric motors.

The world's largest engine

The Wärtsilä RT-flex96C is a turbocharged, two-stroke reciprocating diesel engine designed to power large container ships. It is the world's largest engine.

The engine was built in the Aioi Works of Japan's Diesel United, Ltd, and has a length of 26.59-27 metres, a height of 13.5 metres, and weighs over 2,300 tonnes. Its 14-cylinder version has a power output of 84.42 Megawatts (114,800 bhp). The Wärtsilä RT-flex96C achieves better performance with lower fuel consumption and lower harmful emissions.

The RT-flex96C is a true giant among engines, with its fourteen cylinders that can generate 107,389HP with more than 7,000,000Nm of torque — enough to power an entire suburban town. The engine weighs 2,300 tons and stands 44 feet tall and 90 feet long – more than a four-story building.

The Wärtsilä RT-flex96C engine was installed on the Emma Mærsk, a cargo ship that can carry 11,000 20-foot shipping containers at a speed of 31 knots, while most other ships in its class typically cruise at 20 knots.

The Wärtsilä RT-flex96C is not just about size, but also efficiency and innovation. It is a symbol of human ingenuity and innovation, powering the world's largest ships and reducing the environmental impact of shipping.

Electric outboard motors

There are several options available on the market, offering different power outputs, battery capacities, and ranges. For example, the Torqeedo 603 Travel is a compact motor with a power output of 0.8hp and a range of 11nm, while the Evoy Storm is a more powerful motor with a power output of 300hp and a range of 25nm.

One advantage of electric outboard motors is that they produce no oil spills, noise, or CO2 emissions, making them a sustainable and environmentally friendly choice. They can also be more efficient than traditional engines, with improved fuel injection methods and advanced range optimisation technology, resulting in lower fuel consumption and reduced operating costs.

When choosing an electric outboard motor, it is important to consider the size and type of boat, as well as the desired performance and range. For example, a smaller tender or dinghy may require less power and range than a larger sportsboat or RIB. It is also important to ensure that the battery is compatible with the motor and that the overall weight, including the battery, is within the boat's capacity.

Some popular manufacturers of electric outboard motors include Torqeedo, Mercury, Remigo, Thrustme, TEMO, Haswing, ePropulsion, Yamaha, RAD Propulsion, Vision Marine Technologies, and Evoy. These companies offer a range of products with different features and specifications to suit different needs and budgets.

Inboard engines

There are two main types of inboard engines: direct-drive (D-drive) and V-drive. Direct-drive engines face aft and are connected to a drive shaft that protrudes out the bottom of the boat, with a propeller at the end. This type of engine minimises power loss and is highly reliable, but may reduce cabin and seating space. V-drive engines face forward and use a transmission to redirect the drive shaft towards the stern, creating a V shape. This configuration provides more cabin space or additional seating, but some efficiency is lost between the engine and the propeller.

Other types of inboard engines include hydro-jet engines, commonly found on jet skis and small speedboats, which use a turbine instead of a propeller, and Z-drive engines, which are a hybrid of inboard and outboard engines. Z-drive engines have a base plate equipped with one or two propellers that pivot when turning, guiding the boat in the desired direction.

Stirling engines

The Stirling engine is a closed-cycle regenerative heat engine, with a permanent gaseous working fluid. This means that the working fluid is permanently contained within the system, and a specific type of internal heat exchanger and thermal store, known as the regenerator, is used. The regenerator acts as a temporary heat store, retaining heat within the machine and increasing efficiency.

Gas turbine engines

One notable advantage of gas turbine engines is their ability to provide high power-to-weight ratios. This means that they can generate significant power relative to their size and weight, making them valuable for applications where space and weight are limited. Additionally, gas turbines are known for their reliability and ability to deliver consistent performance over extended periods.

However, one of the drawbacks of gas turbine engines is their lower thermal efficiency at low power or cruising output. Because of this, they are often used in conjunction with diesel engines, which are more fuel-efficient for cruising speeds. In passenger ships, gas turbines are sometimes used to reduce emissions in environmentally sensitive areas or while docked in port.

Overall, gas turbine engines play a crucial role in marine propulsion, particularly for vessels requiring high speeds, long-distance travel, or demanding environments. Their combination of power, reliability, and performance makes them a valuable option for specific applications, despite their lower efficiency at cruising speeds.

Frequently asked questions