Project Snapshot
The 141.5-metre Ro-Ro/passenger vessel required urgent repairs due to excessive wear on both shaft sleeves and stern tube bearings.
KIMI completed the tail shaft sleeve replacement, stern tube bearing machining, and onboard installation under class supervision, returning the vessel to service in time for the summer season.
Challenge
The principal challenge was to machine the new sleeves to exact tolerances, achieve a precisely controlled shrink fit, and machine the stern tube bearings to match the final sleeve dimensions and specified operating clearances. The shaft then had to be reinstalled and accurately aligned onboard.
With severe time constraints and zero margins for error, strict dimensional accuracy, exact clearance control, and full process monitoring at every stage were essential. All machining, fitting, verification, installation, and alignment activities were performed under Classification Society supervision.
Complex Manufacturing & Engineering Challenges
Extremely tight dry-docking schedule.
Handling and machining an 18-metre-long tail shaft.
Precision machining and controlled shrink-fitting of the new sleeves.
Achieving correct interference, concentricity, bearing clearances, and accurate shaft alignment.
Zero margin for error under Classification Society supervision.
Propulsion Shaft and Stern Tube Repair Process
INITIAL INSPECTION & DIMENSIONAL VERIFICATION
Shaft condition, runout, straightness, and critical dimensions were recorded.
REMOVAL OF WORN SHAFT SLEEVES
Worn sleeves were removed protecting the underlying shaft material.
SHAFT INSPECTION & SURFACE PREPARATION
Shaft surfaces inspected and prepared, with straightness and runout verified.
MANUFACTURE OF NEW SHAFT SLEEVES
New sleeves were precision-manufactured to OEM specifications and tolerances.
CONTROLLED SHRINK-FITTING
Sleeves installed through controlled shrink-fitting, with interference, concentricity, and runout confirmed.
STERN TUBE BEARING MACHINING
Stern tube bearings were precisely machined to match the sleeve dimensions and achieve the clearances.
ONBOARD FINAL FITTING & ALIGNMENT
Final bearing positioning, shaft installation, operating clearances, and shaft alignment were verified onboard.
FINAL INSPECTION & CLASS ACCEPTANCE
All work was completed under Classification Society supervision and accepted without remarks or non-conformities.
Project Results
✔ Both propulsion shafts inspected and dimensionally verified.
✔ New sleeves manufactured to OEM specifications.
✔ Controlled shrink-fitting achieved the required interference and concentricity.
✔ Reduced vessel downtime by completing the repairs within the scheduled overhaul period.
✔ Stern tube bearings precision-machined to exact clearances.
✔ Onboard installation and alignment completed.
✔ Full class acceptance without non-conformities.
✔ The vessel returned to service on schedule.
Within a tight schedule and with zero margin for error, KIMI restored the complete shafting system through precision machining, controlled fitting, and class-supervised verification.
Precision machining, quick response, and full class compliance.
Why Rely on KIMI
KIMI delivers complete propulsion shaft restoration for shafts up to 25 m, using advanced CNC precision machining, laser cladding where required, and controlled dimensional verification. Sleeve replacement is performed through strict shrink-fitting procedures, ensuring correct interference, concentricity, alignment, and full compliance with class and quality requirements.
Heavy-Duty Shaft Capability: In-house handling and machining up to 25 m.
Precision Restoration & Sleeve Fitting: CNC machining, laser cladding, and controlled shrink-fitting.
Class-Compliant Quality: Controlled inspection under Class supervision.
Reduced Downtime: Integrated in-house and onboard capability speeds return to service.