Marine Propulsion Device Control for Fuel Efficiency
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Solution Overview
Problem
Marine vessels often operate at idle or low speed conditions for extended periods, where only a fraction of the available power is required, leading to inefficient use of propulsion devices and increased maintenance costs.
Innovation Solution
Implementing a system that selectively turns off one or more propulsion devices during idle or light load conditions, adjusting the steering and propulsion behavior of the remaining devices to maintain equivalent run-time hours and reduce maintenance, while allowing for activation or deactivation via a user interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all propulsion devices are operated continuously, then the vessel has sufficient power and thrust availability, but the maintenance costs increase and fuel efficiency decreases during low load conditions
Solution Approach 1:
The system extracts or removes certain propulsion devices from operation when their contribution to the total thrust is minimal. The control module identifies and deactivates specific propulsion devices based on calculated thrust requirements, operating only the necessary subset of devices to meet the commanded thrust while leaving others idle or shut down, thereby reducing fuel consumption without compromising vessel propulsion needs.
Solution Approach 2:
Instead of operating all propulsion devices at partial load (which is inefficient), the system applies partial action by activating only the minimum number of devices required to deliver the needed thrust. This approach is more efficient than running all devices at low efficiency points, as it concentrates power delivery on fewer devices operating at optimal load levels.
2Power
If all propulsion devices are operated continuously, then sufficient thrust is available, but maintenance costs increase due to unequal run-time hours
Solution Approach 1:
The system implements periodic action by cyclically rotating which propulsion devices are active and which are idle. The control module monitors cumulative run-time hours for each device and periodically switches the operational status of devices to balance their usage. This ensures that no single device accumulates excessive wear while maintaining sufficient thrust availability through the coordinated operation of the active subset.
Solution Approach 2:
The system changes the operational parameter of propulsion devices from continuous operation to intermittent operation. By dynamically adjusting which devices are active based on thrust requirements and run-time hour accumulation, the system transforms the operational pattern to achieve both adequate power delivery and equitable distribution of wear across all devices, facilitating more uniform maintenance scheduling.
3Loss of energy
If a subset of propulsion devices is turned off, then fuel efficiency improves, but the system complexity increases due to control requirements
Solution Approach 1:
The control module performs self-service by automatically calculating the optimal subset of propulsion devices to activate based on the commanded thrust and operational conditions. The system independently determines which devices should be active, adjusts their individual thrust contributions, and manages the rotational scheduling without requiring complex external control systems or manual intervention, thereby achieving fuel efficiency through intelligent autonomous decision-making.
Solution Approach 2:
The system incorporates feedback mechanisms where the control module continuously monitors the operational status, thrust output, and cumulative run-time hours of each propulsion device. Based on this feedback, the control module dynamically adjusts which devices are active and how much thrust each should deliver, creating a closed-loop control system that optimizes fuel efficiency while maintaining adequate power availability and balancing device usage.
Data Source
AI summary
A method of controlling two or more propulsion devices on a marine vessel includes receiving a vessel speed, determining that the vessel speed is below a first vessel speed threshold, receiving an operator thrust demand, and determining that the operator thrust demand is below a first demand threshold. At least one of the two or more propulsion devices is then turned off, and a thrust output of at least one remaining propulsion device is adjusted based on the operator thrust demand.