Underwater Hull Inspection Thailand and Propeller Polishing at Koh Si Chang Anchorage
MaxiDive recently completed a professional underwater hull inspection Thailand operation for a commercial vessel at Koh Si Chang Anchorage.
The project combined systematic underwater condition assessment with selected cleaning of accessible underwater components and professional propeller polishing.
The commercial diving team documented hull plating, underwater appendages, sea chest gratings, transducers, ICCP areas, propulsion components and the rudder assembly.
Sea conditions were calm, with underwater visibility varying approximately between 1 and 5 metres during the operation.
Professional underwater camera systems, hydraulic equipment and hand tools were used according to the requirements of each work area.
The resulting photo and video records provided the vessel’s technical team with a clear reference for underwater condition monitoring and future maintenance planning.
Underwater Hull Inspection Thailand at Koh Si Chang Anchorage
The inspection began with a systematic assessment of accessible hull plating and principal underwater components.
The commercial diving team reviewed:
bulbous bow;
vertical sides;
flat bottom;
stern arrangement;
bilge keels;
sea chest gratings;
transducers;
underwater discharges;
ICCP components;
propeller assembly;
rope guard;
stern tube and seal area;
rudder assembly;
visible anodes;
rudder hatch and related fittings.
Overview video was combined with close-range documentation so that both general condition and localized observations could be reviewed afterwards.
Hull Plating Condition
The accessible vertical sides and flat-bottom areas were found in generally very good visible condition.
No significant signs of contact damage or abnormal structural condition were observed across the inspected areas.
The stern arrangement also appeared free from visible cracking or other major abnormalities.
At the bow, localized abrasion was noted on the bulbous bow area.
This type of observation is important to document because localized abrasion can be distinguished from more extensive hull coating deterioration when supported by clear underwater imagery.
The inspected flat-bottom areas did not show significant visible grounding-related abnormalities.
Bilge Keels and Hull Appendages
Accessible bilge keel sections maintained a normal visible profile.
No notable deformation or significant contact damage was identified during the inspection.
Bilge keels are important inspection points because they project beyond the main hull surface and can be exposed to mechanical contact during vessel operations.
The condition of accessible underwater appendages was documented individually rather than treated as part of a general hull overview.
Sea Chest Grating Inspection and Cleaning
Sea chest gratings were inspected for structural condition, position and visible abnormalities.
The gratings appeared securely positioned and properly fastened.
Accessible areas were cleaned where required to improve visibility and allow clearer condition assessment.
The commercial diving team documented:
grating condition;
visible fasteners;
surrounding plating;
marine growth;
structural integrity;
accessibility of the openings.
Clear underwater imagery is particularly useful around sea chest areas because marine growth can otherwise obscure the condition of bars, fasteners and adjacent hull surfaces.
Underwater Transducer Condition
Accessible transducer areas were visually inspected and documented.
The units appeared securely positioned, with no significant visible mechanical abnormalities identified.
Selected marine growth was removed where necessary to improve inspection access and visibility.
The diving team assessed the external condition of:
sensor face;
mounting area;
retaining components;
surrounding hull coating;
visible fasteners.
Underwater visual inspection documents external physical condition but does not replace onboard electronic testing or calibration.
Underwater Discharges
Accessible overboard discharge areas were also included in the inspection.
No significant visible abnormalities were identified on the documented outlets.
The inspection focused on:
outlet condition;
surrounding hull plating;
coating condition;
visible deformation;
marine growth;
signs of external mechanical contact.
This provides the vessel’s technical team with a broader condition reference covering both the main hull and smaller underwater fittings.
ICCP Areas
Accessible ICCP components were assessed visually during the underwater survey.
No significant visible mechanical damage was observed in the documented areas.
The inspection considered:
external component condition;
secure positioning;
surrounding hull coating;
visible impact damage;
marine growth;
abnormal surface condition.
Visual underwater assessment provides useful physical-condition evidence while electrical performance remains subject to the vessel’s appropriate technical testing procedures.
Propeller Assembly Inspection Before Polishing
Before polishing, the propeller assembly was inspected to establish its visible condition.
The diving team assessed:
individual propeller blades;
blade edges;
hub;
boss area;
boss cap;
rope guard;
stern tube area;
visible sealing region.
No evidence of rope or line entanglement was observed around the accessible propulsion components.
The rope guard appeared in good visible condition.
No significant leakage indication was observed around the accessible seal area.
The propeller blades did not show significant visible signs of contact damage, cavitation-related damage or abnormal deformation.
Underwater Propeller Polishing
After the initial condition assessment, the commercial diving team carried out professional underwater propeller polishing.
Accessible blade surfaces were polished systematically to improve the surface finish.
The completed propeller surface was assessed at approximately Grade A using the Rubert Scale.
Propeller surface condition is important because roughness caused by marine deposits or surface deterioration can increase hydrodynamic resistance at the propeller.
Professional polishing restores a smoother surface while also allowing the blades to be examined closely during the operation.
The work included documentation before and after polishing to provide a clear technical record.
Propeller Boss and Associated Components
The boss cap was inspected and appeared securely positioned.
The keeper arrangement was also found intact in the accessible area.
These smaller propulsion components are included in the inspection because their condition can be difficult to assess without direct underwater access.
Close-range photography provides evidence that can later be compared with future inspections.
Rudder Assembly Inspection
The rudder assembly was inspected for visible structural condition, coating integrity and abnormal movement.
No unusual visual movement of the rudder was detected during the inspection.
Accessible areas showed generally very good visible condition.
The diving team documented:
rudder blade surfaces;
coating condition;
weld seams;
visible anodes;
inspection hatch;
associated fittings.
The accessible topcoat and visible weld seams appeared in very good condition.
Rudder Anodes and Inspection Hatch
Visible rudder anodes appeared secure and active.
The rudder inspection hatch was also securely positioned.
No significant visible abnormality was identified around the documented hatch area.
Including these components in the inspection creates a more complete condition record than documenting only the main rudder blade.
Selected Underwater Cleaning
In addition to propeller polishing, selected underwater areas were cleaned where necessary to provide access to component surfaces and support condition assessment.
This included accessible areas around:
sea chest gratings;
transducers;
relevant underwater fittings.
Cleaning was carried out as part of the agreed operational scope at Koh Si Chang Anchorage.
The purpose was both to address marine growth in selected areas and to improve the visibility of underlying components.
Technical Photo and Video Documentation
Every underwater operation becomes more useful when findings can be reviewed after the vessel leaves the anchorage.
MaxiDive documented the operation using underwater photography and video.
The records included:
component overview images;
close-range details;
hull plating condition;
sea chest gratings;
transducers;
propeller surfaces;
rudder condition;
selected appendages;
condition after polishing and cleaning.
This allows technical superintendents and vessel managers to compare future inspection results against an existing condition reference.
Why Combined Inspection and Maintenance Matters
An underwater inspection can identify current condition, but combining assessment with selected maintenance tasks can also provide immediate operational value when appropriate.
In this project, condition assessment and work execution were integrated within one underwater operation.
The vessel’s technical team received documentation covering:
hull condition;
underwater appendages;
propulsion components;
selected cleaned areas;
propeller surface condition;
rudder condition;
ICCP areas.
This provides a more comprehensive underwater picture than reviewing individual components in isolation.
Commercial Diving Services at Koh Si Chang Anchorage
Koh Si Chang Anchorage is one of the principal locations where MaxiDive supports commercial vessels in Thailand.
Available underwater operations can include:
underwater hull inspection;
propeller inspection;
propeller polishing;
selected underwater cleaning;
sea chest inspection;
transducer inspection;
ICCP inspection;
rudder inspection;
underwater CCTV;
technical photo and video documentation.
Each project is planned according to vessel requirements, underwater condition, visibility and technical scope.
Clear Underwater Evidence for Technical Decision-Making
This underwater hull inspection Thailand project at Koh Si Chang Anchorage provided a structured assessment of the hull, appendages, propulsion system and rudder assembly together with selected cleaning and propeller polishing.
The inspected vertical sides and flat-bottom areas showed generally very good visible condition, while localized bow abrasion was documented for technical reference.
Sea chest gratings, transducers, ICCP areas, propulsion components and rudder fittings were systematically assessed and recorded.
Propeller polishing was completed to approximately Grade A on the Rubert Scale, supported by close-range underwater documentation.
The resulting photo and video records provide the vessel’s technical team with a practical reference for future condition monitoring and maintenance planning.
MaxiDive — We work under pressure.
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