I wrote this short article for the newsletter back in 2013 after an MAIB annual report had been published.

The UK MAIB (Marine Accident Investigation Bureau) has recent resurrected the unfortunate accident of the Skandi Foula, in its second 2013 digest, and in addition the industry has identified a couple of other incidents where collisions resulted from mechanical failure. All of them in one way or another seemed to be related to lack of familiarity with aspects of the ship’s mechanical systems.

Podded propulsion controls on a platform ship. Photo Victor Gibson

The Skandi Foula event concerned the operation of the azmuthing main propulsion by the Chief Officer, who was apparently recently appointed to the ship, and although he was familiar with the operation of the azimuthing propulsion in what was described as the ‘semi-automatic’ mode, he was not familiar with the fully manual operation of the system.

He chose to angle the thrusters in a way that when the power was applied to the appropriate control as well as moving the vessel forward the heading of the ship would be altered in the same direction. Ie, if power was increased on the starboard thruster the ships head would move to starboard.

The Chief  Officer had been unable change the heading as required using the bow thruster and so he increased the thrust to one of the aziprops. However the change in heading was insufficient, and the increase in speed to more than four knots made the bow thruster ineffective (my assumption). The Chief Officer put the main propulsion to full astern which would require the initiation of an additional generator by the power management system, but by the time it had started up the generator and put it on line, the ship had collided with the OMS Resolution.

There have also recently been failures of  control systems on other support vessels. In one case a generator failure resulted in the shutting down of a bow thruster and one of the aziprops. The captain was apparently unable to control the vessel with the remaining systems and collided with another vessel. In yet another case a generator failure resulted in the CP propulsion resetting itself to the default full astern, resulting in the vessel colliding with the harbour wall.

These misfortunes have resulted in the companies involved changing their procedures to make sure that sufficient power is available for all possible activities during port operations.

Now here’s the question. These requirements are so basic that it is difficult to believe that the appropriate pre-departure checks were not carried out. The MAIB report does not tell us what the ‘semi-automatic system’ for directional control of a vessel fitted with azimuthing propulsion was, but it seems likely that either the joystick or the autopilot offered the best means of their collective operation.

And of course it might have been one of these system which was being used when the other unnamed vessel lost a generator resulting on one of the thrusters and one of the azimuthing propulsion units shutting down. Given an omnidirectional thruster aft and a bowthruster  many shipmasters would have no problem at all in controlling the direction and speed of their craft. In fact some might prefer it.

 And as for the failure of the CP system in the full astern position.  Back in the day we understood that this was a common default setting for this form of propulsion, on the basis that most ships spend nearly all their time dashing between places, so in the event of a CP failure it would be best for them to come to a halt as soon as possible. But in the early years of the development of marine support to the offshore industry it was common for ships to present themselves stern on to offshore installations, and so the default position for CP failure was altered to neutral. 

Apart from a lack of preparation for the maneuvering activities which are honestly difficult to forgive, surely the guys out there need some assistance with the operation of the azimuthing propulsion. Some of these systems cannot be put in the astern mode, and rely on the pod rotating to provide the astern power, and all of them probably work better when the vessels are out there under the crane, than in the provision of forward motion and directional control.  

 Actually there are ships which recently entered service with such poorly designed driving positions that not all the individual controls can be operated at the same time. The assumption is made by the designers that some form of collective stick will be used. 

Added to all these systems is Voith Schneider propulsion with which a few offshore vessels are now fitted. This is probably the simplest to use if the modern design follows the traditional Voith control systems. I was once Mate of an Isle of Wight ferry fitted with VS propulsion, having two rotors at the stern and one at the bow. There was  central control station at which the helmsman was situated and one on either bridge wing. To change the heading one turned a horizontal wheel on top of the station, to move forward one rotated a wheel on the side of the station in the fore and aft line, and to move bodily sideways one rotated a wheel in the athwartships line on the front of the station. It was therefore possible, for instance, to move forwards and sideways at the same time. It seems so simple. 

            The MAIB made four recommendations about the Skandi Foula accident of which the last was this:

            The port authority for this harbour had no procedures in place to ensure appropriate

levels of ship-handling competence for vessels moving within the harbour; it assumed that ship managers would ensure appropriately trained personnel would be in control of their ships. Harbour authorities have the powers to demand ship-handling competence standards and, as part of their risk assessment and compliance with the Port Marine Safety Code, should mandate the level of ship-handling competence applicable to all vessels operating within their port confines.

Interesting, but surely to demand ship-handling competence we would be entitled to ask for some guidance and training, and it seems likely that representatives of the port in question, which must surely be Aberdeen will be visiting vessels and asking for the appropriate guidance, and proof of the levels of competence of the drivers.