Every chief engineer has more machinery than condition monitoring budget. Vibration analysis, oil sampling and thermography all claim to catch failures early, but each one sees a different set of faults, on different machines, at a different point before failure. Spend the first part of the budget on the wrong method and the critical failure is still invisible. This guide compares what each method actually sees and how early it warns, matches methods to shipboard machinery, and sets out a scoring method for deciding which condition monitoring to fund first. Book a demo to see oil results, vibration readings and thermal surveys tracked against each machine.
Condition monitoring: vibration, oil or thermal first?
One budget, three methods. Match each method to the failure it sees earliest.
Condition monitoring methods: what each one actually sees
Machinery Lubrication puts it plainly: oil analysis and vibration work together, not against each other, and each leaves gaps on its own. Thermography covers a third area, heat, which is where most electrical faults show first.
| Failure mode | Vibration | Oil | Thermal |
|---|---|---|---|
| Imbalance, misalignment, looseness | Strong | No | Late |
| Gear tooth damage | Strong | Partial | No |
| Rolling bearing wear, early stage | Late | Strong | Late |
| Plain (journal) bearing wear | Hard | Strong | Late |
| Water, dirt and fuel in the oil | No | Strong | No |
| Oil degraded or wrong viscosity | No | Strong | No |
| Loose or corroded electrical connections | No | No | Strong |
| Overloaded circuits, blocked cooling | No | No | Strong |
Based on Machinery Lubrication and Fabrico’s comparisons. “Late” means the method sees the fault only once damage is well advanced.
Condition monitoring early warning: how much time each method buys
Early warning is what you are paying for. The P-F interval is the time between the first sign a method can pick up (P) and functional failure (F). The longer it is, the more time you have to plan the repair instead of reacting to it.
Warning before failure on rolling element bearings: Palo Verde nuclear plant
From Machinery Lubrication. A Monash University gearbox study found oil analysis flagged threatening conditions on average 15 times sooner than vibration, though it missed some failure types altogether.
Same plant: who caught the fault?
Running both methods closed a gap that either one alone would have left open.
Condition monitoring by machine type on board
The method follows the machine. Vibration struggles on slow-speed, reciprocating and hydraulic machinery and on journal bearings, which describes much of a ship’s engine room. Fast rotating auxiliaries are where it is strongest.
Main and auxiliary engines
Reciprocating, with plain bearings. Lube oil trends catch wear, fuel dilution and water first.
Stern tube and steering hydraulics
Water ingress and particles are the main threats. Vibration has little to read here.
Gearboxes and screw compressors
Machinery Lubrication lists multistage gearboxes and screw compressors as best served by both methods together.
Turbochargers and purifiers
High-speed rotors, where imbalance and bearing faults show clearly in the spectrum.
Pumps, fans and electric motors
Misalignment, looseness and soft foot cause most failures, and vibration sees all three.
Switchboards and motor control centres
One scan covers a whole panel. Scan under load, or hot connections stay hidden.
Switchboard thermal surveys sit alongside routine electrical checks. See our marine switchboard and electrical distribution inspection guide. On the engines, oil trends feed straight into overhaul timing, as covered in our main engine overhaul schedule and inspection guide.
See oil, vibration and thermal results on the same machine
Stop chasing lab reports, spreadsheets and survey PDFs. Every reading lands on the machine it belongs to.
Choosing which condition monitoring to fund first
Start from risk, not from the technology. Score each machine on how bad its failure would be and how likely it is, then fund the method that sees that machine’s main failure mode earliest.
List the critical machinery
Start from the equipment your ISM system identifies as critical.
Score and place it
Use consequence and likelihood, with failure history from your planned maintenance records.
Name the main failure mode
Wear, misalignment, contamination or heat. That decides the method.
Fund the top-right first
Then widen coverage as results start to pay back.
The grid is an example only. Your own scoring will place machines differently.
Oil analysis
Most ships already sample engine oil. Widen it to stern tube, hydraulics and gearboxes, and trend every result.
Thermography
Regular scans of switchboards and motor control centres under load: broad cover in a single visit.
Vibration
Handheld route readings on critical rotating plant, then online sensors where the risk justifies them.
A typical order for an engine room built around slow-speed engines. A ship with critical high-speed rotating plant may put vibration first.
Condition monitoring and class: CBM survey arrangements
Condition monitoring can also earn survey credit. DNV describes condition based maintenance as a survey arrangement that combines scheduled and predictive maintenance, carried out with an approved service supplier, with maintenance done once a decline in condition is seen. ABS offers similar notations; a GasLog LNG carrier was the first to receive ABS SMART (MHM) and PMP-CBM together. Any CBM arrangement sits on top of an approved planned maintenance scheme. Our planned maintenance system guide covers that foundation.
Condition monitoring programme checklist
How Marine Inspection brings condition monitoring together
Marine Inspection puts lab oil reports, vibration route readings and thermal survey findings on the machine they belong to. It trends them and raises a job when a reading crosses its limit. The panel below is illustrative.
ME lube oil
Iron trend steady; water 0.05%
DG2 engine
Fuel dilution rising; injector job raised
TC No. 1
Overall velocity within limits
SW cooling pump 2
1x peak growing; alignment check due
Main switchboard
Last scan clear; next due in 4 months
Stern tube
Water steady; sample due at next port
Condition monitoring: frequently asked questions
Which condition monitoring method should a ship start with?
Is vibration analysis better than oil analysis?
Does vibration analysis work on the main engine?
What does thermography find on a ship?
Can condition monitoring earn class survey credit?
Three methods, one machinery health picture
Bring oil, vibration and thermal results together, and spend the next part of your budget where the data says it matters.
