Full Hull Cleaning Koh Si Chang with Propeller Polishing and Marine Growth Removal
- MaxiDive
- 3 hours ago
- 4 min read
MaxiDive Co., Ltd. completed a full hull cleaning Koh Si Chang operation for a commercial bulk carrier at Koh Si Chang Anchorage, Thailand. The underwater work included full hull cleaning, appendage cleaning, sea chest grating cleaning, bilge keel cleaning, and propeller polishing using hydraulic and hand tools.
The vessel was found heavily covered by soft and hard marine growth, including algae, slime, barnacles, tube worms, and oysters. MaxiDive’s diving team carried out the cleaning operation to remove marine fouling, restore underwater surface condition, and support vessel efficiency without dry docking.
Full Hull Cleaning Koh Si Chang Scope
The full hull cleaning Koh Si Chang scope included underwater cleaning of the vessel’s hull plating, flat bottom, vertical sides, appendages, sea chest gratings, bilge keels, discharges, propeller assembly, and rudder area.
The work covered:
full hull marine growth removal;
flat bottom cleaning;
vertical side cleaning;
sea chest grating cleaning;
appendage and bilge keel cleaning;
discharge area inspection and cleaning;
propeller polishing;
rudder and drain plug inspection;
underwater photo and video documentation.
The work was performed under challenging sea conditions with limited visibility, requiring experienced commercial divers, controlled equipment handling, and structured underwater reporting.
Heavy Marine Growth on Hull Plating
Before cleaning, the vessel’s hull was heavily covered by both soft and hard marine growth. The reported fouling included algae, slime, barnacles, tube worms, and oysters on both port and starboard sides.
The flat bottom was also heavily covered by hard marine growth, including barnacles, tube worms, and oysters. Loss of topcoat consistent with anchor chain abrasion was noted around the bow area. The visible paint condition across the vessel was generally fair, although some areas of bare steel were observed.
After cleaning, the flat bottom and vertical sides were reported free from marine fouling. No concave weld seams were noted, and no visible damage or structural anomalies were reported during the inspection.
Sea Chest, Appendage and Bilge Keel Cleaning
The sea chest gratings were heavily blocked by barnacles before cleaning. MaxiDive’s divers cleaned all sea chest gratings using hand tools, helping restore clear water flow through the inspected openings.
The gratings were found secure, with no movement, contact damage, or visible abnormality reported. Bilge keels were covered with both hard and soft marine growth and were also cleaned using hand tools.
Discharge areas were found with no structural anomalies, although partial blockage by barnacles was noted. ICCP components and transducers were reported with no contact damage or abnormality. Drain plugs were secure in place, with no leakage noted.
Propeller Polishing and Rupert Scale Improvement
The propeller assembly was found heavily fouled before cleaning. The report recorded approximately 70–95% hard marine growth, soft marine growth, and calcareous deposits on the propeller assembly.
MaxiDive’s diving team cleaned the propeller assembly using hydraulic tools fitted with 3M Scotch pads. Initial blade surface roughness, excluding marine fouling, was recorded as Rupert Scale “E”.
After initial cleaning, all blade surfaces, blade palms, and hub areas were polished using silicate grit polishing discs. Upon completion, the average blade surface roughness was recorded as Rupert Scale “A”, equal to approximately 1 micron CLA.
This improvement is important because propeller roughness directly affects propulsion efficiency. A smoother propeller surface helps reduce turbulence, improves water flow across the blades, and supports better vessel performance.
Propeller Blade Defects Documented
During the propeller inspection, several blade defects were documented for technical review. The report noted missing material on one propeller blade leading edge near the tip, cavitation on another blade leading edge, and additional missing material on a separate blade leading edge near the tip.
The stern shaft area was found free from marine fouling.
Documenting these findings is important because hull cleaning and propeller polishing are not only cleaning operations. They also provide vessel managers with underwater evidence that can support maintenance planning, future dry-dock preparation, and technical assessment.
Rudder and Anode Findings
The rudder was found free from marine growth after inspection. The paint coating was reported in fair condition, with areas of missing paint down to bare steel on the leading edge.
The rudder niche area was free from marine growth. The rudder hatch was found secure in place, and the drain plug was secure with no leakage noted. Sacrificial anodes were reported secure, although fully depleted.
These findings were documented as part of the underwater service report to support the vessel’s maintenance records and future technical planning.
Why Full Hull Cleaning Matters
For commercial vessels operating in tropical waters, marine growth can accumulate quickly and significantly affect performance. Heavy fouling on the hull, appendages, sea chest gratings, and propeller assembly can increase resistance, reduce speed, increase fuel consumption, and affect operational efficiency.
Professional underwater hull cleaning helps vessel operators:
reduce drag from marine growth;
improve underwater hull condition;
support fuel efficiency;
restore propeller surface performance;
reduce unnecessary dry-dock dependency;
identify visible damage or coating issues;
document underwater condition for technical review.
By combining hull cleaning with propeller polishing, MaxiDive provides a complete underwater maintenance solution for vessels at anchorage.
Commercial Diving Support at Koh Si Chang Anchorage
Koh Si Chang Anchorage is one of Thailand’s key maritime locations for commercial vessels requiring underwater inspection, hull cleaning, propeller polishing, and technical support without dry docking.
MaxiDive provides underwater hull cleaning, propeller polishing, sea chest cleaning, marine growth removal, underwater inspection, and commercial diving services across Thailand’s major ports and anchorages.
With 2,111 completed projects, 964 clients, 21 locations, and 5 diving units, MaxiDive supports shipowners, managers, charterers, and technical departments with reliable underwater ship maintenance services throughout Thailand.
Conclusion
MaxiDive successfully completed the full hull cleaning Koh Si Chang operation, including heavy marine growth removal, sea chest cleaning, appendage cleaning, bilge keel cleaning, propeller polishing, rudder inspection, and underwater documentation.
The vessel’s flat bottom and vertical sides were cleaned free from marine fouling, sea chest gratings were cleared, and the propeller surface was improved from Rupert Scale “E” to Rupert Scale “A”. The final report also documented propeller blade defects, coating condition, rudder condition, and anode status for technical review.
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