Define what the evidence must decide.
Begin with the operational question. A periodic health programme, a one-off abnormal-vibration investigation, an overhaul verification and a contractual acceptance test may use some of the same instruments but require different point plans, operating states, comparison criteria and reporting language. Record the decision owner, available history, expected action and who must review the result.
Decision required
Continue operation, shorten the interval, inspect, repair, restrict an RPM band, verify maintenance or demonstrate an agreed acceptance basis.
Evidence recipient
Owner, manager, superintendent, chief engineer, yard, maker, consultant, class or flag reviewer as applicable.
Scope boundary
Named machines, points, states, dates, exclusions and whether transmitted structural or habitability vibration is outside scope.
Comparison basis
Healthy baseline, sister point, previous route, maker criterion, project specification or confirmed applicable standard.
Use vessel machinery condition monitoring for repeatable surveillance and trend decisions. Use marine machinery vibration analysis when a symptom needs controlled diagnostic measurements. Formal acceptance, class-notation work and ordinary troubleshooting are not automatically interchangeable.
Identify the machine and the failure question before placing a sensor.
The asset record should distinguish the driver, driven equipment, transmission and support arrangement. Capture make, model, serial or shipboard tag, rating, normal speed range, bearing type where known, coupling, foundation, mounts, connected services, redundancy and recent maintenance. Criticality should consider safety, operational consequence, redundancy, repair lead time and whether deterioration can be detected before failure.
| Asset ID | Machine train | Duty / rating | Speed range | Recent work | Failure question | Criticality / action owner |
|---|---|---|---|---|---|---|
| ASSET-___ | Driver / coupling / driven unit | ___ | ___ r/min | ___ | ___ | ___ / ___ |
| ASSET-___ | Driver / coupling / driven unit | ___ | ___ r/min | ___ | ___ | ___ / ___ |
Make every measurement point repeatable.
Assign a controlled point ID and show its physical location on a photograph or drawing. Record the component, bearing or casing position, horizontal/vertical/axial direction, sensor attachment, surface condition, access limitation and sensor identity. A label such as “pump vibration” is not enough for a future engineer to reproduce the reading.
| Point ID | Component / location | Direction | Attachment | Sensor ID | Quantity / units | Photo or drawing |
|---|---|---|---|---|---|---|
| PT-___ | DE / NDE / casing / mount / foundation | H / V / A | Magnet / stud / probe / other | ___ | ___ | REF-___ |
| PT-___ | DE / NDE / casing / mount / foundation | H / V / A | Magnet / stud / probe / other | ___ | ___ | REF-___ |
For a source-path-receiver question, distinguish machinery casing points from mounts, foundation, connected pipework, deck structure and occupied-space receiver points. A machine-condition result should not silently become a habitability or hull-response conclusion.
Connect each record to the state that produced it.
Vibration and process indicators can change with RPM, load, electrical demand, valve position, flow, temperature, lubrication state, generator combination, thruster use, vessel speed, propeller condition, sea state and nearby machinery. Record the variables material to the suspected failure mode. If the target state cannot be achieved, identify the deviation instead of presenting the result as equivalent.
| Run ID | RPM / frequency | Load / process | Equipment lineup | Vessel state | Temperatures / pressures | Deviation |
|---|---|---|---|---|---|---|
| RUN-01 | ___ | ___ | ___ | Berth / sea / trial / in service | ___ | ___ |
| RUN-02 | ___ | ___ | ___ | Berth / sea / trial / in service | ___ | ___ |
Record enough setup detail to interpret and repeat the signal.
Declare the transducer, calibration or verification status, mounting, measurement quantity, amplitude convention, frequency range, sampling or analysis settings, record duration, resolution, filtering, windowing and any mathematical integration. Velocity RMS, acceleration peak, displacement peak-to-peak, shaft-relative motion and casing motion answer different questions and must not be merged into one undefined “vibration level.”
| Setup ID | Sensor / analyser | Certificate / check | Quantity / amplitude | Frequency range | Record / resolution | Processing note |
|---|---|---|---|---|---|---|
| SET-___ | ___ / ___ | ___ | mm/s RMS / g peak / other | ___ Hz | ___ | Filter / window / integration |
| SET-___ | ___ / ___ | ___ | mm/s RMS / g peak / other | ___ Hz | ___ | Filter / window / integration |
A calibration certificate supports traceability for the instrument. It does not prove that the correct machine point, direction, mounting, bandwidth, operating state or comparison criterion was selected.
Separate absolute level, baseline change and rate of change.
For machinery baseline and trend planning, compare like with like: the same asset, point, direction, attachment method, sensor family, quantity, frequency range and documented speed/load state. Keep three decision views visible rather than forcing every machine into one universal alarm.
- Absolute level: compare the defined quantity with the confirmed machine-specific maker, project or applicable standard basis.
- Change from baseline: identify departure from a documented healthy state under comparable conditions.
- Rate of change: distinguish a stable elevated condition from accelerating deterioration and set the next interval accordingly.
If speed, load, point, attachment, units, bandwidth or processing changed, label the comparison as qualified or invalid. Do not create a smooth trend by combining incompatible records.
Escalate the evidence before naming a probable fault.
Overall values are useful for screening. Diagnosis normally requires a pattern tied to running speed, load, direction, phase, waveform or other corroborating evidence. Select the next technique because it can test a failure hypothesis, not because every instrument function must be used.
| Observed evidence | Useful next comparison | Boundary |
|---|---|---|
| Overall magnitude changed | Comparable repeat, spectrum, operating state and sister point | A high number alone does not name imbalance, misalignment or looseness. |
| Narrow RPM-sensitive peak | Run-up/coast-down amplitude and phase; machine, support and deck response | One steady reading cannot prove resonance. |
| Impulsive/high-frequency content | Waveform, suitable envelope method, lubrication, temperature and inspection | Mounting and process impacts can imitate bearing damage. |
| Repeated coupling/bearing failure | Both machine sides, phase, alignment, soft foot, pipe strain and load | Replacing the part again does not establish root cause. |
| Process performance changed | Pressure, flow, current, valve state, temperature and vibration together | Separate process change from mechanical deterioration. |
The marine machinery measurement and diagnosis guide and seven-pattern investigation guide provide the related technical routes.
Prepare first-party proof without inventing a vessel or result.
When a real project can be disclosed with written permission, record the decision, controlled scope, comparable data, diagnostic boundary, action and matched verification. Until permission exists, use this blank structure. It is not a completed case study and contains no customer, vessel, fault, pass statement or improvement figure.
Trigger
What alarm, trend, symptom, failure or acceptance decision initiated the work?
Controlled evidence
Which assets, points, runs, setup records and corroborating checks were captured?
Finding boundary
What does the data support, and which causes remain untested?
Maintenance action
What inspection, repair, restriction or monitoring interval was recommended?
Verification
Was the same point/setup/state repeated after the action, and what changed?
Permission record
Who approved publication, what was redacted and which wording was accepted?
Do not add a vessel, customer, class, flag, defect, downtime saving, numerical improvement, testimonial or acceptance statement without contemporaneous evidence and publication permission.
Make the maintenance decision traceable.
- The decision, scope, machines, exclusions and report recipient agree with the approved request.
- Every result has an asset, point, direction, operating-run and acquisition-setup reference.
- Units, amplitude convention, frequency range, processing and comparison basis are unambiguous.
- Trend comparisons identify any change in speed, load, point, mounting, sensor or processing.
- Measured facts, diagnostic interpretation, confidence and untested alternatives are separated.
- Recommended urgency, operating limitation, inspection/maintenance action and next interval are named.
- Acceptance statements identify the exact maker, project, standard, class or flag basis and reviewer responsibility.
- Customer, vessel, photograph and report-extract publication permissions are documented.
This evidence pack supports field planning and report QA. It does not replace the controlling maker manual, standard, contract, class rule, flag instruction, safety procedure or competent diagnostic review.
Confirm the controlling revision for the actual machine.
- ISO 17359:2018: general procedures for a machine condition-monitoring programme.
- ISO 20816-1:2016: general machine-vibration measurement and evaluation guidance.
- ISO 13373-2:2016: processing, analysis and presentation of vibration data.
- ISO 13379-1:2025: data interpretation and diagnostic-approach guidance.
Official source links establish document identity and scope; they do not establish applicability or a universal limit for every onboard machine. Check the current edition, machinery-specific part, maker criteria, class/flag requirement and contract at scope confirmation. ISO 20816-1 is under revision, so its replacement status should be checked when the project begins.
Turn the evidence pack into a controlled onboard scope.
Send the machinery register, symptom or trend, point history, RPM/load range, previous repairs and required decision. The measurement route and deliverables can then be defined before attendance.
Scope condition monitoringScope vibration diagnostics