Stern Tube Bearing & Seal Replacement for Multipurpose Vessel

Project Overview

A 12,500 DWT multipurpose vessel required stern tube bearing replacement and aft shaft seal renewal during intermediate survey at a Chinese repair yard. The BV surveyor had flagged excessive bearing clearance and minor oil seepage at the aft seal during the previous annual survey.

Challenge

• Stern tube bearing dimensions needed to be measured after shaft withdrawal — cannot be pre-ordered to exact size
• BV-approved bearing material required (white metal or composite)
• Shaft seal must match existing stern tube housing dimensions precisely
• Total drydock time allocated: 14 days (shaft work = critical path)

Our Solution

Hicool pre-positioned semi-finished bearing blanks at the manufacturer while the vessel was in transit to the yard:

• Aft Stern Tube Bearing — white metal (Babbitt), BV-certified, final-machined to measured dimensions within 48 hours of shaft withdrawal
• Forward Stern Tube Bearing — composite (Thordon-equivalent), BV-approved, machined to survey measurements
• Aft Shaft Seal Assembly — complete lip seal unit with chromium oxide wear ring, matched to shaft diameter
• Spare Seal Rings — 2 sets for future maintenance

Results

• Bearings delivered to yard within 48 hours of receiving final measurements — critical path not delayed
• BV surveyor approved both bearings and shaft seal at installation inspection
• Vessel completed sea trials with bearing temperature and shaft alignment within specification
• Total stern tube component cost: 50% less than European seal OEM pricing

Key Takeaway

Stern tube work is always on the critical path during drydock. Pre-positioning semi-finished components and final-machining after measurement can save days of drydock time. Hicool's approach coordinates manufacturer readiness with vessel drydock timing.