What checks and measurements of tail shaft and stern tube to be done during dry docking?
Due to the considerable weight of the propeller, the tail shaft is subject to a bending stress. There are however other stresses which are likely to be encountered. There is a torsional stress due to the propeller resistance and the engine turning moment, and a compressive stress due to the prop thrust. All these stresses coupled with the fact that the shaft may be in contact with highly corrosive sea water makes the likelihood of corrosion attack highly probable.
Following examinations of tail shaft and stern tube to be conducted during dry docking:
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Before the periodic inspection the bearing weardown should be measured.
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After shaft removed given thorough examination.
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On water lubricated shafts the integrity of the fit of the bronze liner should be checked by tapping with a hammer along its length listening for hollow noise indicating a separation.
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Measure wear of shaft.
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Examine key way for cracks especially the nut thread area. Replace rubber rings
