Ship Vibration Survey Field Record Pack

Choose the survey by the decision, not by the symptom alone.

“The ship vibrates” can describe discomfort in a cabin, motion of a deck or panel, a machinery fault, shafting behaviour or a transient caused by a particular operating combination. Before selecting points, record what must be decided, who will use the report, which vessel conditions can be reproduced and which acceptance document—if any—actually governs the work.

Freeze the governing inputs before the test day.

Record the request, vessel state, spaces or structures, decision owner, witnessing parties, required operating points, planned measurement quantities, report deliverables and exclusions. If a specification, comfort notation, class rule, flag instruction or standard is named, identify the exact edition and clause supplied by the project. Publication status alone does not amend a signed contract, and a supplier should not imply that IACS, a class society or a flag has approved the supplier.

Keep a copy or controlled reference for every governing document. If the project cannot confirm the basis before attendance, report the measurements and limitations without converting an indicative comparison into a formal pass statement.

Translate a felt symptom into reproducible receiver evidence.

Interview wording is evidence about when and where the symptom occurs, not a diagnosis. Mark the exact berth, cabin, bunk, seat, work position, deck bay, bulkhead, panel or equipment foundation. Record who experiences or observes the issue, the body posture or activity, start and stop conditions, dominant direction, audible rattle, visible motion and whether the response changes with shaft speed, engine load, thruster use, heading, sea state or nearby machinery.

The practical ship cabin vibration at certain RPM guide explains why a narrow operating band can produce a strong response without identifying the source by itself.

Synchronise every channel with the condition that produced it.

Ship response can vary with engine or shaft RPM, propeller pitch, vessel speed, displacement, trim, draught, loading condition, heading, sea state, water depth, thruster use, generator and pump combinations, HVAC operation and mooring condition. Select only variables relevant to the decision, but record them at each run rather than relying on a test-day summary. Use a shared time source where instruments and bridge or engine logs must be correlated.

For a controlled speed sweep, predefine the step size, hold time, direction of change and safe excluded ranges. A run-up and coast-down may reveal different behaviour. Any operating restriction remains the vessel operator’s safety decision.

Make locations, axes and processing auditable.

Assign a channel ID before recording. Capture the accelerometer or transducer identity, calibration certificate or field-check reference, mounting method, orientation, measurement quantity, units, amplitude convention, sampling rate, record duration, frequency range, weighting, filtering, integration and analysis settings. Note cable routing, magnetic or adhesive mounting limitations, local surface condition and any channel saturation or dropout.

Keep human-response measurements tied to actual use.

For occupied spaces, record the receiver position and body relationship: floor location, bunk or seat, posture, contact surface, activity and measurement axes. Identify whether the purpose is comfort, complaint investigation, workplace exposure or an agreed vessel-acceptance test. These intents are not interchangeable. The selected frequency weighting, evaluation quantity, duration and spatial plan should follow the confirmed project basis and competent technical review.

The current habitability reference and legacy-contract guide explains the published replacement relationship between the current and withdrawn ship-habitability documents. Confirm the actual contractual edition rather than assuming the newest publication automatically controls.

Separate source, path and receiver before assigning cause.

Structural work may require response points on a deck, shell, superstructure, bulkhead, panel, foundation or support together with reference channels near propulsion or machinery excitation. Show coordinates using deck, frame, longitudinal and vertical references. Record direction, local stiffness or boundary condition, nearby discontinuities, added mass, loose fittings and whether the point represents global response, local response or a suspected transmission path.

A response peak at a steady speed can support a resonance hypothesis, but a defensible mode or source conclusion may need a controlled sweep, phase relationships, operational deflection information, modal testing, calculation or other corroboration. Record what was measured and what remains untested.

Reject or qualify data before it reaches the conclusion.

Review each run for stable speed and load, correct operating lineup, adequate record duration, sensor security, synchronisation, overload, dropout, transient events, movement near the receiver, doors or panels rattling and unplanned changes in sea or mooring condition. Repeat a run while conditions are still available when a validity check fails.

Make the evidence and limitations reviewable.

• The decision, vessel condition, spaces or structures, exclusions and recipients match the approved scope.
• Every reported result has a receiver or structural point, axis, channel setup, run and operating-state reference.
• Measurement quantity, units, amplitude convention, frequency range, weighting, duration and processing are unambiguous.
• Applicable document, edition, clause, project specification and any class or flag review role are stated factually.
• Measured facts, evaluation, diagnostic interpretation, confidence and untested alternatives are separated.
• Invalid, unavailable or non-equivalent conditions remain visible rather than being omitted from the narrative.
• Plots, tables, photographs and drawings use consistent identifiers and readable scales.
• Recommended investigation, repair, operating restriction or matched retest identifies the decision owner.

A report can support a buyer, owner, yard, designer, manager, class or flag review, but the reviewer controls its own acceptance process. Vessel Doctor should not claim approval, authorisation or guaranteed acceptance unless a specific, current document proves it.

Prepare real proof without inventing a result.

Before corrective work, freeze the points, axes, setup, RPM or speed steps, machinery lineup, loading condition and evaluation outputs needed for a matched retest. After the action, record every unavoidable difference. A percentage change is meaningful only when the compared records are sufficiently equivalent and the calculation basis is shown.

Confirm the document that controls the actual project.

• ISO 20283-5:2016 describes measurement, evaluation and reporting of vibration with regard to habitability on passenger and merchant ships.
• ISO 6954:2000 is listed by ISO as withdrawn, with ISO 20283-5:2016 identified as the new version.
• ISO 20283-2:2008 addresses measurement of structural vibration on ships excited by propulsion machinery.
• ISO 2631-1:1997 provides general requirements for evaluating human exposure to whole-body vibration.

The official records establish document identity, publication status and broad scope. They do not establish which document, limit, notation or acceptance process applies to a particular vessel. Confirm current status, amendments, contract language, class rules, flag instructions, vessel type and competent-review requirements when the scope is agreed.