Voluntary class notation or owner target
Environmental & Acceptance Testing · SERVICE 18
Underwater Radiated Noise Survey
Propellers, propulsion machinery and onboard equipment radiate sound into the water. Underwater radiated noise is increasingly considered in vessel design, environmental programmes, research operations and voluntary class notations. Vessel Doctor supports carefully planned URN measurement campaigns with specialist partners, suitable instrumentation and documented operating conditions.
PERFORMANCE VERIFICATIONClear evidence→
VESSEL DOCTORUnderwater Radiated Noise Survey
SURVEY PROFILEEnvironmental & Acceptance Testing
18/19
Original category-specific diagnostic visual
01
WHY THIS SURVEY MATTERS
Evidence before assumption.
Underwater noise can change with propeller cavitation, speed, loading, water depth, machinery configuration and measurement geometry. Valid results require far more than placing a hydrophone beside a vessel; the test range, background, tracking and processing method must match the reporting purpose.
02
MEASUREMENT SCOPE
What we measure.
- ✓Frequency-resolved underwater sound pressure
- ✓Source-level estimates under the selected method
- ✓Vessel speed and operating condition
- ✓Background and self-noise
- ✓Narrowband or one-third-octave characteristics
- ✓Comparative runs before and after modifications
03
TIMING & APPLICATION
When to request it.
Research and survey-vessel requirements
Quieter-vessel design programme
Propeller or propulsion modification evaluation
Environmental impact or port study
Baseline for fleet decarbonisation/noise initiatives
04
SURVEY PROCESS
A controlled route from plan to finding.
Define
Confirm the decision, vessel condition and evaluation basis.
Prepare
Agree locations, safe access, instruments and operating matrix.
Measure
Capture traceable data with conditions documented during measurement.
Interpret
Evaluate against the agreed basis and isolate meaningful patterns.
Report
Issue findings, limitations and focused next actions.
05
TECHNICAL DELIVERABLE
What you receive.
- ✓Measurement concept and feasibility review
- ✓Test-range and operating-condition plan
- ✓Calibrated acoustic dataset
- ✓Processing and correction methodology
- ✓Results against the agreed reference basis
- ✓Recommendations for source investigation or mitigation
06
STANDARDS & PROJECT CRITERIA
The governing basis comes first.
Use the revised IMO guidelines for reduction of underwater radiated noise from shipping, including MEPC.1/Circ.906 where applicable, the relevant ISO 17208 series, class notation and project-specific criteria. Treat IMO guidance as voluntary unless made mandatory by another applicable requirement.
Important
Explore our standards directory↗Acceptance remains subject to the applicable flag administration, classification society, contract, vessel specification and authorised reviewing party.
ASIA + WORLDWIDE ATTENDANCE
Underwater Radiated Noise Survey wherever the vessel needs it.
Vessel Doctor coordinates this service for vessels in Singapore, India, Malaysia, Sri Lanka, Indonesia, Thailand, wider Asian maritime centres and ports worldwide. The scope can support technical managers, marine superintendents, ship agents, owners, operators, shipyards and consultants who need documented onboard evidence.
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SERVICE FAQ
Questions project teams ask.
Every scope is confirmed against the actual vessel, timing and decision requirement.
01Can URN be measured in any port?+
Not reliably. Water depth, background noise, traffic, geometry and permissions may make a location unsuitable.
02Is underwater noise the same as onboard noise?+
No. They involve different propagation media, instrumentation, metrics and acceptance purposes.
03Does the IMO set a universal mandatory URN limit?+
The referenced IMO guidelines are generally voluntary; specific projects, ports, owners or class notations may set targets.
04Can you locate the source of excessive URN?+
Comparative runs and onboard vibration/noise measurements can help identify contributors, but complex source-path analysis may require additional modelling.
START A TECHNICAL DISCUSSION
Plan your underwater radiated noise survey.
Share the vessel, location, operating condition and reporting purpose. We will help shape a focused, technically defensible survey scope.