HSOS Germany and HSOS Belgium jointly carried out stern tube boring on a vessel in dry dock at a German shipyard – including flange face machining and in-house laser alignment within 2.5 shifts.
Situation
A vessel was placed in dry dock at a German shipyard on short notice. The stern tube – the primary bearing assembly for the propeller shaft – showed signs of wear and required refurbishment before the next operational period. Tight shipyard schedules demanded an immediate, coordinated response.
Challenge
The stern tube spanned a total length of 4,500 mm with different bore diameters at both bearing locations. The pre-measured misalignment was 3 mm – a deviation that had to be brought within tolerance to ensure reliable operation of the shaft line. In addition, the flange faces on both ends required machining to guarantee a flat, properly sealed mating surface for adjacent components.
Approach
Before any cutting commenced, HSOS conducted an independent laser measurement of the as-found geometry. This in-house metrology step is integral to our workflow: it provides independent baseline data, establishes the target dimensions and enables final quality verification without reliance on third-party measurement services.
Scope of work:
- Boring of both bearing locations to different nominal diameters
- Face turning of both stern tube flanges
- Continuous alignment monitoring throughout machining
- Final laser measurement for documentation of achieved tolerances
Team
The job was executed jointly by HSOS Belgium and HSOS Germany. Cross-border resource pooling within the HSOS group allows specialists and equipment to be mobilised at short notice – a decisive advantage when unplanned dry-dock windows arise.
Result
Within 2.5 shifts, both bearing bores and flange faces were machined to specification, misalignment was reduced to the required tolerance band and the vessel was released on schedule. Full measurement records were handed over on-site.
Summary
This project illustrates how HSOS combines short-notice response, proprietary metrology and multi-site team coordination to deliver repeatable machining quality on safety-critical marine components – even under severe time pressure.