In-Situ Tailshaft Machining Repair

Client: MMS Ships
Industry: Marine & Shipbuilding
Location: Hull, United Kingdom
Duration: 2 Days
Service: Tailshaft Machining (In-Situ Repair)
https://royceonsitemachining.com/services/tailshaft-machining/

Project Overview

Royce Onsite Machining, in collaboration with MMS Ships, was engaged to deliver a precision in-situ repair on a vessel following a propeller failure. The incident had caused severe damage to the propeller shaft bearing journals, a critical component responsible for maintaining alignment and operational integrity of the propulsion system.

Due to the vessel’s status and the constraints of a tightly scheduled dry-dock period, a conventional shaft replacement was not feasible. A high-precision on-site machining solution was therefore required to restore the shaft while preserving its original geometry, structural integrity, and service life.

Scope of Work

To address the damage, Royce Onsite Machining deployed custom-built orbital machining equipment, designed and manufactured in-house for this specific application. The operation focused on restoring the bearing journal surfaces using precision machining techniques carried out entirely in situ.

Key activities included:

• Establishing accurate machining datums on a worn and irregular shaft surface
• Precision machining of damaged bearing journals with minimal material removal
• Maintaining strict tolerances while preserving the original shaft centreline
• Ensuring structural integrity and alignment for continued operational performance

The machining process was carefully controlled to extend the usable life of the existing shaft rather than replace it, reducing both downtime and cost.

Technical Highlights

• Shaft diameter: 260 mm
• Machining tolerance achieved: within 0.03 mm
• Flatness achieved: 95%
• Surface finish: 0.3 Ra

These results demonstrate a high level of precision, particularly given the constraints of working in a dry-dock environment on an significant vessel.

Outcome

The project was successfully completed within a single day of machining work, meeting the strict deadline imposed by the vessel’s dry-dock schedule.

Key outcomes included:

• The propeller was replaced while retaining the original shaft
• Full restoration of bearing journal surfaces to operational standard
• Elimination of the need for a costly and time-consuming shaft replacement
• All dimensional, alignment, and performance requirements successfully met
• Vessel returned to service on schedule with minimal downtime

Conclusion

This project highlights the effectiveness of in-situ machining as a cost-efficient and time-critical solution for marine shaft repair. By combining precision engineering with specialised orbital machining technology, Royce Onsite Machining successfully restored a critical propulsion component, extending the life of the original shaft and avoiding major replacement work.

The successful completion of this repair demonstrates the value of advanced onsite machining techniques in supporting the marine and shipbuilding industry, particularly in high-pressure dry-dock environments.