Hull Cleaning Gibraltar
Call us now
+350 200 68811
Email now
ops@hullcleaninggibraltar.com
North Mole Rd
Gibraltar
Call us now
+350 200 68811
Email now
ops@hullcleaninggibraltar.com
North Mole Rd
Gibraltar

Case Studies

Underwater Ship Repair Case Studies

Underwater Ship Repair Case Studies: Success Stories

  1. Emergency Hull Patching of a 300m Crude Oil Tanker
    • Issue: Vertical side shell penetration causing minor oil seepage at East Anchorage.
    • Solution: 6-hour rapid response with class-approved magnetic cofferdam and underwater wet welding.
    • Result: Seepage stopped; vessel cleared by ABS for onward voyage.
  2. Propeller Blade Straightening for a 10,000 TEU Container Ship
    • Issue: Severe vibration due to bent propeller tip from floating debris.
    • Solution: Underwater cold-straightening using hydraulic jacks at Western Anchorage.
    • Result: Vibrations eliminated; fuel efficiency restored to 98% of design specs.
  3. Sea Chest Valve Replacement via Bespoke Cofferdam
    • Issue: Leaking main engine intake valve requiring urgent internal repair.
    • Solution: Custom-fabricated underwater cofferdam installed to create a dry seal.
    • Result: Valve replaced afloat; avoided $125/175k dry-dock deviation cost.
  4. Rudder Pintle Clearance Measurement & Inspection
    • Issue: Suspected steering gear wear during transit through the Strait.
    • Solution: High-precision underwater measurement using digital calipers and visual recording.
    • Result: Technical report delivered to owner in 2 hours; confirmed safe operation limits.
  5. Afloat Crack Arresting on a Bulk Carrier’s Transverse Bulkhead
    • Issue: 15cm stress crack detected during routine IWS.
    • Solution: Stop-drilling and high-tensile steel plate welding (AWS D3.6M).
    • Result: Structural integrity secured; permanent repair deferred to next scheduled dry-dock.
  6. Full Anode Array Replacement for a Panamax Bulker
    • Issue: 85% depletion of sacrificial anodes leading to hull pitting.
    • Solution: Underwater replacement of 42 zinc anodes at Gibraltar anchorage.
    • Result: Cathodic protection restored; hull corrosion arrested.
  7. Bow Thruster Grates Repair & Marine Growth Removal
    • Issue: Blocked thruster tunnel leading to reduced maneuverability in port.
    • Solution: Underwater welding of broken grate bars and high-pressure cleaning.
    • Result: 100% thruster efficiency restored for safe berthing.
  8. Underwater Sealing of Stern Tube Leak
    • Issue: Oil leak from stern tube seal threatening environmental fines.
    • Solution: Installation of a specialized hydro-tight seal bypass system.
    • Result: Leak contained; vessel allowed to transit to final discharge port.
  9. Echo Sounder & Speed Log Transducer Replacement
    • Issue: Malfunctioning navigation sensors below the waterline.
    • Solution: Diver-led transducer replacement using internal blanking techniques.
    • Result: Navigation systems back online within 6 hours.
  10. Propeller Blade Cropping on a Damaged LNG Carrier
    • Issue: Fractured propeller tip causing severe engine imbalance.
    • Solution: Precision underwater cropping of opposing blades to restore balance.
    • Result: Engine stress reduced; vessel maintained 14-knot transit speed safely.
  11. Overboard Discharge Pipe Plugging (Emergency)
    • Issue: Corroded overboard pipe leaking seawater into the engine room.
    • Solution: Emergency underwater plugging with mechanical expansion bungs.
    • Result: Internal pipe repair completed while afloat.
  12. Bilge Keel Fracture Repair for a Ro-Ro Vessel
    • Issue: 2-meter section of bilge keel detached during heavy seas.
    • Solution: Underwater cutting of damaged section and smoothing of edges.
    • Result: Hydrodynamic drag reduced; prevented further hull tearing.
  13. In-Water Survey (IWS) for Class Extension (DNV)
    • Issue: Scheduled dry-docking delayed due to cargo commitments.
    • Solution: Full CCTV IWS including hull, rudder, and tailshaft measurements.
    • Result: DNV granted 6-month extension based on our high-quality report.
  14. Sacrificial Anode Installation on Sea Chest Grids
    • Issue: Accelerated corrosion inside intake chambers.
    • Solution: Installation of specialized compact aluminum anodes.
    • Result: Internal corrosion rate reduced by 90%.
  15. Clearing of Entangled Fishing Nets from Propeller Shaft
    • Issue: Gemi yolda kaldı (Vessel disabled) due to heavy nylon net entanglement.
    • Solution: Emergency dive at night; hydraulic cutting of 50kg of netting.
    • Result: Propulsion restored within 3 hours of arrival.
  16. Sealing of Empty Ballast Tank for Internal Weld Repairs
    • Issue: Internal crack requiring hot-work but threatened by sea pressure.
    • Solution: External magnetic patch applied to the hull.
    • Result: Internal dry repair completed safely at Gibraltar anchorage.
  17. Welding of Doubler Plates on Corroded Tugboat Hull
    • Issue: Localized thinning found during pre-purchase inspection.
    • Solution: Underwater welding of 12mm steel doubler plates.
    • Result: Hull thickness compliance restored for insurance purposes.
  18. Underwater Polishing of CPP (Controllable Pitch Propeller)
    • Issue: Heavy calcium deposits on blade hubs affecting pitch mechanism.
    • Solution: Precision polishing and hub mechanism inspection.
    • Result: Smooth pitch transition restored; fuel savings of 4%.
  19. Rudder Blade Void Space Leak Repair
    • Issue: Water ingress into rudder blade causing steering sluggishness.
    • Solution: Underwater drilling, draining, and sealing of the ingress point.
    • Result: Rudder buoyancy and response time returned to normal.
  20. Removal of Invasive Species for Australian Port Entry
    • Issue: Vessel denied entry due to biofouling on the niche areas.
    • Solution: Detailed cleaning of sea chests, rudder trunk, and bow thruster.
    • Result: "Clean Hull" certificate issued; vessel entered Australia without delay.
  21. Cathodic Protection System Audit & Replacement
    • Issue: ICCP system failure; temporary protection needed.
    • Solution: Rapid deployment of hanging anodes and hull-mounted sacrificial units.
    • Result: Vessel protected until next dry-dock.
  22. Cleaning and Inspection of Speed Log Sensors
    • Issue: Inaccurate speed readings affecting fuel monitoring.
    • Solution: Delicate underwater hand-cleaning of sensor faces.
    • Result: Accurate data restored for fuel optimization software.
  23. Underwater Welding of Sea Chest Grate Hinges
    • Issue: Grates falling off, risking debris entry into pumps.
    • Solution: Reinforcement of hinges using underwater fillet welds.
    • Result: Intake system secured against large debris.
  24. Propeller Rubert Grade A Polishing at Night
    • Issue: Tight schedule; vessel arriving at 22:00 for bunkers.
    • Solution: Full night-dive operation with high-intensity underwater lighting.
    • Result: Operation completed before bunkering finished; zero time lost.
  25. Pre-Purchase Condition Report for 50,000 DWT Bulker
    • Issue: Buyer required an independent view of the hull before final payment.
    • Solution: 8-hour comprehensive survey of all underwater assets.
    • Result: Identified minor grounding damage; buyer successfully renegotiated price.

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