USCG Exam PracticeMaintenance, machine tools, drawings, and tables
Under 46 CFR §61.20-23, when propelling machinery is located aft, the rebushing clearance limit for the after stern tube bearing compared to the amidship machinery standard is:
- A. The same as for amidship machinery
- B. 1.6 mm (0.0625 in) greater than the amidship limit
- ✓ 1.6 mm (0.0625 in) less than the amidship limitCorrect
- D. Half the clearance specified for amidship machinery
Why C is correct
46 CFR §61.20-23(a)(2) states that where propelling machinery is located aft, the after stern tube bearing must be rebushed when weardown is 1.6 mm (0.0625 in) less than the applicable clearance for propelling machinery located amidship. This tighter limit reflects the shorter bearing span in aft-engine arrangements.
Cited:46 CFR §61.20-23