What Is Underwater Hull Inspection?
Underwater hull inspection is the assessment of a vessel's hull condition while the ship remains afloat — no dry-docking required. In Singapore, one of the world's busiest bunkering and ship repair hubs, underwater hull inspection using ROV technology has become the preferred method for vessel owners and managers seeking to monitor hull health between scheduled dry-dockings.
An ROV (Remotely Operated Vehicle) is deployed alongside the vessel at anchorage or berth. The underwater drone systematically scans the entire hull surface, recording high-definition video of the coating system, biofouling coverage, cathodic protection anodes, sea chests, propeller blades, rudder surfaces, and all underwater appendages. The class society surveyor monitors the live video feed from the surface and directs the ROV pilot to investigate any areas of concern.
This approach — formally known as UWILD (Underwater Survey In Lieu of Dry-Docking) — is accepted by all major classification societies for intermediate hull surveys. For vessel owners, it eliminates the massive cost and operational disruption of dry-docking, which typically runs $200,000-$500,000 and takes 2-3 weeks out of a vessel's trading schedule. In Singapore, where anchorage and berth space is readily available, UWILD surveys can be completed in a single day.
What We Inspect on the Hull
Our underwater hull inspection covers every component below the waterline. Each element is assessed, documented, and rated according to class society condition grading standards.
Hull Coating Condition
We assess the anti-fouling and anti-corrosive coating system across the entire hull — flat bottom, vertical sides, boot top, and bilge radius. Coating breakdown, blistering, chalking, and bare steel exposure are documented by location and severity.
Biofouling Assessment
Marine growth is classified by type (slime, algae, barnacles, tubeworms, mussels) and coverage percentage per hull zone. We follow the IMO Biofouling Guidelines and provide data for the vessel's Biofouling Management Plan — increasingly required by port states including Singapore.
Cathodic Protection
Sacrificial anodes are measured for remaining wastage percentage. Impressed Current Cathodic Protection (ICCP) anodes and reference cells are visually inspected. We map anode locations against the vessel's CP design drawing to verify adequate protection coverage.
Propeller and Rudder
Propeller blades are inspected for edge damage, cavitation erosion, fouling, and pitch accuracy. The rudder, rudder pintle, and stock are checked for corrosion, fouling, and clearances. Stern tube seal condition is assessed where visible.
Hull Inspection Pricing in Singapore
Our hull inspection pricing is based on vessel size and survey scope. All prices are fixed and include workboat, ROV mobilisation, and reporting.
| Vessel Type | Length | Price Range (SGD) |
|---|---|---|
| Harbour Craft / Tug | Up to 50m | $3,000 — $5,000 |
| Coastal / Feeder Vessel | 50-100m | $5,000 — $8,000 |
| Handysize / Supramax | 100-200m | $7,000 — $10,000 |
| Panamax / Post-Panamax | 200-300m | $10,000 — $13,000 |
| VLCC / Large Container Ship | 300m+ | $12,000 — $15,000 |
| Add-on: UT Thickness Measurement | Any size | +$2,000 — $5,000 |
Compared to dry-docking: A dry-docking in Singapore costs $200,000-$500,000 including dock fees, staging, cleaning, painting, and lost revenue during the 2-3 week dock period. An in-water hull survey saves vessel owners 95% or more of that cost while satisfying class society requirements.
Our Hull Inspection Process
Survey Planning and Coordination
We coordinate with the vessel owner, ship manager, and class society surveyor. The survey date is scheduled around vessel movements and tidal conditions. MPA notifications are submitted for operations at Singapore anchorages.
Workboat Mobilisation
Our team and ROV equipment mobilise to the vessel location by workboat. For vessels at Singapore anchorage (Eastern Working Anchorage, Western Anchorage, or Changi anchorage), transit time is typically 30-60 minutes from our base.
ROV Hull Survey
The ROV is deployed and systematically covers the hull in a predetermined pattern — port side, starboard side, flat bottom, stern area including propeller and rudder, and bow area including bulbous bow and bow thruster. The class surveyor monitors the live video feed and directs close-up examination of any anomalies.
Data Processing
Video footage is processed and annotated. Biofouling coverage is quantified per hull zone. Anode wastage is measured. Coating defects are mapped to hull drawings. All data is compiled into a structured format aligned with class society requirements.
Report Delivery
The complete hull inspection report is delivered within 5-10 working days. Reports include hull condition overview, zone-by-zone assessment with annotated images, biofouling rating, CP assessment, propeller condition, and recommendations — formatted for class society submission.
Class Society Compliance
Our hull inspection service meets the UWILD requirements of all major classification societies operating in Singapore. We work directly with class surveyors to ensure every survey satisfies their specific standards.
- DNV — hull survey procedures compliant with DNV Rules for Classification, Part 7. ROV video quality and coverage meet DNV's documentation requirements for UWILD surveys.
- Lloyd's Register — surveys follow LR's ShipRight procedures for in-water surveys. We accommodate LR surveyors' specific examination requirements for hull plating, appendages, and sea connections.
- Bureau Veritas — ROV inspection data meets BV's technical requirements for underwater inspection. Reports are formatted for BV's survey documentation system.
- ClassNK — surveys comply with NK's Guidance for In-Water Surveys. We have experience with NK surveyors' focus areas including bilge keel attachments and sea chest gratings.
- ABS — hull surveys follow ABS Rules for Survey After Construction. ROV documentation standards meet ABS Guide for Use of Remotely Operated Vehicles.
Biofouling Assessment and IMO Compliance
Biofouling management is an increasingly important aspect of hull inspection. Singapore, as a signatory to the IMO Biofouling Guidelines, expects vessels to maintain biofouling management plans and records. Australia and New Zealand already enforce strict biofouling requirements, and more port states are following.
Our hull inspections include a detailed biofouling assessment that quantifies marine growth by type and coverage across defined hull zones. This data supports the vessel's Biofouling Record Book and provides evidence of biofouling management compliance. Where biofouling levels exceed acceptable thresholds, we can recommend in-water cleaning services — avoiding the need for an unscheduled dry-docking that could cost the vessel owner hundreds of thousands of dollars.
For vessels calling at Australian or New Zealand ports, our biofouling reports are formatted to satisfy Australian Department of Agriculture documentation requirements, helping vessel operators avoid the risk of being denied port entry or required to undergo costly hull cleaning at the port of arrival.
Frequently Asked Questions
Get a Free Hull Inspection Quote
Tell us your vessel name, size, and location in Singapore — we reply with a fixed-price hull inspection quote within 24 hours.