Propellers that can be revolved, so-called azimuth propellers, are becoming increasingly common. But there are several risks associated with them, largely since it is a new way of manoeuvring. One example is of a ship that was approaching its arrival position. The ship had drifted due to wind and needed to compensate. The captain did this by making a wide turn towards the position and then turning one of the propellers to avoid getting too close to another ship. The push which resulted was apparently reinforced by the propeller water from the second ship, which led to the captain turning the propeller in a different direction. The reaction was probably too fast, because the propeller did not turn in the way the captain had intended. The ship moved in the wrong direction and came too close to the shore. Another example of the risks involved with azimuth propellers is their reverse function. The propeller can reverse despite the unit pointing forwards. This avoids turning the whole unit, but the disadvantage is weaker propulsion. Some units can combine reverse and propeller pitch. The risk is that backwards and forwards become mixed. One such case occurred last spring when a ship had engaged ”reverse pitch” when manoeuvring in port. In the final stage of the mooring manoeuvre this was forgotten and the ship collided with the quayside. In this context it should be pointed out that the captain was the sole operator on the bridge at the time and had to communicate with the rest of the crew on the radio. The shipping company proposes better procedures and manning on the bridge.
SFu ref. 06.05.02 TSS 2012-1076, 06.05.02 TSS 2011-1698