For Rocupe's propulsion problem I suggest magnets for propeller drive. For the steering swing seals, those can be higher than waterline. Those pod boats are pretty high from water.
For ships those are azimuth thrusters. (if you want google those)
Clays and gravels are different at different places/countries. Look your nearby road and pipeline excavations.Are the pipeline trenches over 8 feet deep without support? I think that 8 feet deep is stupid. Maybe 5 feet excavation and 2-3 feet high wood wall. Don't kill yourself.
My guess is that bearing broke and shockload broke the stem. And now maybe bearing is bigger. The old design hook bearing is over the dynamic load chart.
Hello. Have been reading this thread and I think that 120mm diameter ball bearing with 3mm balls is near limit speeds for bearing balls. At that 3000 rpm
New guy here don't shoot. About two years ago liebherr 295000 hook broke. Now crane has been repaired. Crane hook looks bit different. The nut is a lot bigger than before.