When replacing the drive shaft dripless seals in my boat, I also had the cutlass bearings replaced (inside the supports near the propeller) while the driveshafts were pulled out. When driving the boat back to its homeport after the repairs, I noticed a strong vibration, sounding like a clothes drier tumbling out of control with an unbalanced load of laundry. When the marina that had replaced the bearings looked at the problem, they discovered that they had missed seeing bearings (somewhat hidden) inside the driveshaft tubes. Apparently when reinstalling the starboard driveshaft and pushing the shaft back through the shaft tube, the bearing (which was probably very old) broke into pieces, which caused the vibration when the driveshaft was turning. The replacement of the broken shaft tube bearing fixed the vibration problem. So, the lesson here is to be sure to check for bearings in the driveshaft tubes when replacing the cutlass bearings!
Jim Geier
Cheoy Lee Trawler 55