Updated 24 November 2025.
Selecting the right propulsion system is a defining factor for the performance, efficiency and cost of any vessel. Among the propulsion solutions commonly used in high-speed and workboat applications are the Water Jet (WJ), the Fixed Pitch Propeller (FPP) and the Controllable Pitch Propeller (CPP). Each technology has strengths and limitations — but when fuel efficiency, thrust performance and operational flexibility matter, the differences become significant.
In this article, we will discuss the differences between the WJ and the CPP, highlight their operational characteristics, and explain how converting from Water Jet to CPP can yield substantial fuel savings, lower emissions and reduce total cost of ownership.
A Water Jet generates thrust by accelerating a high-speed stream of water through a pump and nozzle. Thrust is created by reaction force, pushing water aft to drive the vessel forward.
Key characteristics:
A Controllable Pitch Propeller uses blades with a fixed diameter but adjustable pitch, meaning the blade angle can be continuously optimized during operation.
Key characteristics:
When selecting a propulsion system for your vessel, it is important to consider the different variables or characteristics that are important to your means of operation. Both the Water Jet and the CPP has great features and advantages, it really just depends on your vessel and its intended use.
Investing in the right propulsion system can heavily influence consumption, environmental impact and the performance of your vessel.
Water Jets offer operational benefits, but several characteristics impact energy usage:
Field data and hydrodynamic theory show that Water Jets can be up to 30% less efficient than a well-designed CPP system under many operational profiles. This typically requires:
Efficiency drops quickly under real-world conditions such as:
Even small deviations from ideal conditions can affect thrust and fuel burn.
From high-speed operation (e.g., 40–50 knots) down to moderate speeds (20–30 knots), Water Jets experience a steep fall in efficiency. Most commercial and offshore vessels operate in this mid-range for large portions of their duty cycle.
Despite lower efficiency, Water Jets are ideal when:
For specialized missions, these advantages can outweigh fuel considerations.
Read more: How to reduce the operational cost of your high speed vessel
CPP systems offer several strong benefits that directly improve efficiency and reduce operational costs:
Unlike Water Jets, CPPs maintain strong efficiency from low to high speeds. This results in:
Variations in weight do not drastically affect performance. CPPs can adjust blade pitch to maintain:
By adjusting pitch, a CPP can avoid overloading engines during:
CPPs require less input power for the same thrust, enabling:
This makes CPP an attractive solution in modern low-emission vessel designs.
Vessels that operate at zero or low speed, such as offshore wind farm service vessels, aquaculture vessels or harbour craft, benefit from the high static thrust that CPP systems deliver.
Compared to Water Jets:
Read more: What is important when selecting propulsion technology
Water Jets dominate certain segments of the market due to their shallow-water capability, speed and manoeuvrability. However, in many commercial and offshore operations, CPP systems consistently deliver higher efficiency, lower fuel consumption and reduced environmental impact.
A CPP system is most effective when designed holistically, including propeller, tunnel, brackets and rudder system. When optimized as a complete package, CPP propulsion can dramatically reduce operational cost.
Before converting or selecting a new system, operators should perform a thorough evaluation that considers:
Although Water Jets may be cheaper to install, the long-term fuel savings and lower emissions offered by CPP solutions can outweigh the initial investment, especially for vessels with diverse duty cycles and variable operating conditions.