Unlock Machinery Data With Torsional Vibration
Detection of Propeller Fouling Through Torsional Load Behaviour During Service
Customer Profile
- Customer: Commercial vessel operator running ocean-going bulk / general cargo vessels
- Asset: Main propulsion system (engine–shaft–propeller train)
- Engine make & model: DOOSAN MAN B W -S50MC-C [ 8,700 kW @120RPM ]
- Operating Hours: In excess of 56,000 hours
- Operating profile: Repeated voyages at comparable draft, speed, and power settings
Context
- The Complete Vib360 system comprising engine and propeller health monitoring and shaft power measurement was installed as part of a POC trial that the ship owner intended to carry out to test the efficacy of the system.
- During multiple voyages at similar operating conditions, Vib360 identified a progressive change in torsional load behaviour of the propeller.
- No alarms were active and no machinery defects had been reported.
Problem Statement
- Propeller fouling typically causes gradual load increase and fuel efficiency loss, while conventional parameters remain within limits.
- Early detection is difficult without intrusive inspection or indirect fuel comparisons.
Objective of Vib360 Assessment
- Detect changes in propulsion load under comparable conditions
- Distinguish external load increase from internal engine issues
- Provide actionable insight for maintenance planning
Measurement Setup
- Shaft Rotation monitored by Magnetic Pickup Unit (MPU)
- Continuous monitoring of angular speed variation and torsional energy
- Comparative analysis across repeated voyages
Physics-Based Findings
Vib360 showed progressive increase in torsional energy required to maintain the same shaft speed.
Load-related harmonic amplification was observed without combustion imbalance.
Mechanical / Operational Interpretation
The stable combustion behaviour combined with increased torsional load indicated rising external hydrodynamic resistance.
This behaviour was consistent with progressive propeller fouling rather than engine malfunction.
Action Taken
The operator inspected the propeller and confirmed fouling. Third party underwater inspection confirmed heavy fouling
Outcome and Value
- Based on our report of increased fuel consumption and increased torsional disturbance of the propeller, owner was able to take corrective measures saving considerable fuel.
CBM and Class Relevance
Demonstrates condition-based detection of external load changes aligned with CBM principles.
Technical Significance
Confirms Vib360’s capability to be a decision making tool for management