A classification survey of the propeller shaft withdrawn from the stern tube to inspect for corrosion, cracking, and bearing wear.
In practice
A non-destructive examination (NDE) of the shaft, typically using magnetic particle inspection or dye penetrant testing, is carried out to identify surface-breaking defects not visible to the naked eye. Bearing clearances are measured and compared to class-approved limits; worn bearings must be renewed. The condition of the stern tube seals — critical for preventing seawater ingress and oil leakage under MARPOL requirements — is also inspected. If a shaft is found to meet specified criteria for surface condition and dimensional tolerances, and a type-approved bearing monitoring system is fitted, some classification societies permit an extended interval between withdrawals, reducing drydocking cost and off-hire time.
Regulatory detail & full definition
A tailshaft survey (also termed propeller shaft survey or intermediate shaft survey) is a classification society examination of the propeller shaft, stern tube, and related bearings, conducted at defined intervals — typically every five years for vessels with conventional oil-lubricated stern tubes, or as determined by the vessel's HSLC (harmonised survey and loading cycle). The survey requires withdrawal of the propeller shaft from the stern tube so that the shaft surface can be inspected for corrosion, pitting, fretting, fatigue cracks, and journal wear.
A non-destructive examination (NDE) of the shaft, typically using magnetic particle inspection or dye penetrant testing, is carried out to identify surface-breaking defects not visible to the naked eye. Bearing clearances are measured and compared to class-approved limits; worn bearings must be renewed. The condition of the stern tube seals — critical for preventing seawater ingress and oil leakage under MARPOL requirements — is also inspected. If a shaft is found to meet specified criteria for surface condition and dimensional tolerances, and a type-approved bearing monitoring system is fitted, some classification societies permit an extended interval between withdrawals, reducing drydocking cost and off-hire time.