USCG Exam PracticeMaintenance, machine tools, drawings, and tables
Under 46 CFR, when must a water-lubricated rubber stern tube bearing be rebushed?
- ✓ When any water groove is half the original depthCorrect
- B. When clearance reaches 6.4 mm regardless of shaft diameter
- C. When the Officer in Charge, Marine Inspection determines it necessary
- D. When weardown is 1.6 mm less than the amidship machinery standard
Why A is correct
46 CFR §61.20-23(b) specifies that water-lubricated rubber bearings must be rebushed when any water groove is half the original depth. The 6.4 mm clearance and the 1.6 mm reduction apply to non-rubber water-lubricated bearings, and the OCMI determination applies to oil-lubricated bearings.
Cited:46 CFR §61.20-23