Although cracking at the big ends of the taper sections of water lubricated propeller shafts (as shown in Figure 1) is considered to be rare, it is something which is confirmed from time to time according to survey reports, etc. This kind of damage is usually discovered after a propeller shaft has been withdrawn during propeller shaft inspections and in some cases may require the immediate replacement of the shaft, which is something that will greatly impact the ship's operation. Figure 2 shows a recent example of such cracking that required the immediate replacement of the propeller shaft.

(To be continued)