MV Aurora
During the Christmas New Year Cruise 2004-5 the Starboard Main Motor failed which required both motors to be replaced.
So, what actually happened. She was on her way back to Southampton from Madeira at the end of her Christmas cruise, due to arrive into Southampton at 0700 hrs on the 9th of January in readiness to sail out that evening at 1700 hrs on her world cruise. Whilst underway and at around 0630 hrs she suffered failure of the Starboard Main Motor. Full inspection of the issue was not possible due to needing to stop the ship completely in order to fully open up thus the ship continued on to Southampton on one shaft, the Port motor at maximum power whilst the starboard motor was allowed to free wheel.
Here is a plant over view. 4 off Diesel Generators which generate the electricity for all the ships needs, be it hotel consumers, engine and also propulsion use. The main motors or PEM’s as we refer to are in Compartment 14. PEM means Propulsion Electric Motor. The diesel Generators are in compartments 11 and 12.
The motors as fitted were 20 MW electric Motors. You will note the coolers to keep the motors cool are side mounted. This in itself presented an obstacle latter once the decision was taken to change the motors out.
This is a cross sectional view of one of the PEM’s You will see the Rotor, Stator exciter etc. The rotor weighs some 95 Tonnes. The stator weighs some 90 Tonnes.
This picture was taken but does not portray the reality at the time. The cover had been removed in order to try and view the problem however the rotor and shaft are rotating at approximately 90 to 100 RPM, hence considerable caution was taken.
This picture was also taken while the ship was on passage.
Close up view of the stator slots with the coils removed. As you will see a lot of burning and melting of the Stator has taken place.
Once all the coils were removed, all debris was cleaned out and preparations made in order to run the motor. You can see that quite a bit of metal was removed in order to get the area clean.
View of Stbd PEM prior to final sea trials before decision to change out. You will see the size of the motor in comparison to a Man.
Stator windings marked up and insulated after cuttings and re-jointing of some coils. Just below the lamp you can just see a man behind the windings who is finalising the insulation etc before final closure for the final trials.
Some of the papers ran jokes about the whole incident which at the time did not seem that funny but do now.
This was run in the local evening paper in Southampton.
Starboard Propulsion Electric Motor, Forward View, prior to removal.
You can see in this view the coolers on the side of the motors which I mentioned previously. This became an issue for the change out due to the new motors having the coolers on the top of the motors.
How do you move something which is so heavy if you cannot lift it ?
The ship was built around the motors so how do you get them out, up, down, sideways ?
Due the amount of work involved who is capable and has the facilities at such short notice to do the work? The ship would have to be in a Dry Dock for nearly 60 days if we had spare motors to start with.
New ones will take 8 months to make.
The pems are situated in Compartment 14. The view is an overview of the ship in the Dry Dock. The dry dock is not wide enough to take them out through the side. Up is not an option due the amount of ship which would have to be removed, the only way is down through the bottom of the ship but that in itself is not easy.
The only way for the Pem’s to be removed is first to move the motors outboard towards the hull of the ship, then down through the bottom of the ship and then aft under the ship to the aft end of the Dry Dock where they can be lifted out by a crane. Note however that just outboard of the Pem’s is a main support stanchion which is structural to the support and construction of the ship. The calculated weight bearing down on that support was some 180 Tonnes.
In order to move the motors side ways before moving down the stanchion had to be removed. Thus the decks above had to be supported in some way and thus new supports which would not interfere with the transition of the motor had to be constructed. The next issue was that once the motor was on the dock bottom unfortunately the head room between the motor and the ship was insufficient and thus more of the hull aft of the access opening had to be cut out in order to get the motor underneath the ship.
The section of Hull or amount of hull which was required to be removed was substantial and too much to remove in one section. Thus it was removed in 6 off sections. The total amount of Hull removed in weight each side was 25 Tonnes.
This view is a cross section of the ship and dry dock showing how the motors had to be moved outboard and then down into the dock bottom. Also the hull form which was in the way and also had to be removed.
Due the further removal of Hull after of the motors in order to get them under the ship it also presented further support problems and or support problems. This required more modifications and stanchions supporting as you will see. It is not different from making access into a person rib cage and ensuring that the cavity does not collapse during access.
Where the men are removing the plates supports is the bulkhead of the Trim Tank. It will necessary to remove this complete bulkhead and or tank in order to move the motor in due course.
The motors are situated in Compartment 14 however in order to get these motors under the ship sections of the hull need to be removed in Compartment 15. This meant that in some areas extra support was required even in the sections to be removed. In this case you cans see the lightening holes which will require welded inserts in order to give them extra support once the hull is cut out.
The ship had to be maintained on its services and as several of these services were routed through and outboard of the main motors in compartment 14 arrangements had to be made to bypass these various services in order keep the ship “Alive” so to speak. We had to run numerous temporary pipes in order to achieve this.
At the time of the failure the Crown Princess was under construction in Italy. The motors for her were actually in Italy and had only just arrived that week ready for fitting during the construction. The motors were near identical but not quite. The main issue was that the rotor couplings and bed plate arrangements were different. Thus if we were to use the Crown motors we had to pick and mix so to speak. Other issues which needed to be resolved were that technically although the motors were for the Crown Princess, we did not own the Crown Princess, the ship yard did so we had to purchased the motors from the building yard. That then raised the issue of a possible time delay in construction which had to be addressed as well. Further, the motors were too large to drive across Europe and thus they had to be shipped from Italy all the way to Bremen.
Also, as an aside, the Lloyds surveyor in the build yard at the time was a good friend who rote on the side of the motors before they were shipped, “Property of David Jewkes Chief Engineer Mv Aurora Germany” He is now the principle surveyor in charge in Seattle, good old USA.
Compartment 15 at frame 70 looking from below. Extra supports visible in way of frame stanchion 70. In the case of the equipment you can see, it would normally be supported of the hull but as that has been removed it is now supported of the deck above by welding in temporary supports.
View directly bellow and looking up at frame 70 stanchion in the starboard side. One can see the stanchion supports which have been cut through above and also in the upper right hand corner you will see the base of a Galley Grey water drain tank which has been supported from above.
The second section of Hull having been burnt out being lowered to the dock bottom. This is from the after section of Compartment 15 and you will see just inside the ship the swimming pool equipment.
The last sections of Hull on the Port side being removed and lowered out to the dock bottom. One can just see Pem and the ballast tank bulkhead. The men are standing in what is left of the ballast tank.
All removals complete and ready for Motor Removal Port Side. Once full access for removal was made a heavy lift company Lastra were brought in. In order to move the motor they first had to raise each motor and place them onto skids which would enable them to slide them in the direction required. Obviously they also had to some how move them outboard but not into free air. The constructed a frame work out of wooden blocks and jacks to enable this.
Heavy Lift Company Lastra prepare there equipment in order to remove the 185 Tonne motors. You will se in the right-hand picture the frame which the motor will eventually sit on erected and being raised by means of the wooden blocks, 3 inches at a time.
Lastra at the point of moving the Motor outboard. The frame has been raised to the height required and thus the motor is now made ready for sliding outboard onto the frame.
The motor now on a skid is moved hydraulically outboard and onto the larges Jenga frame I have ever seen.
Port motor outboard and being lowered to the dock bottom. You will see the transverse skids which the motor was moved on and just in view on the right hand side is the new temporary support to enable the motor to be removed without the ship collapsing on top of it.
The port motor on its way aft in the dock towards the dock gate in readiness for lifting out. Only just passes the Propeller.
The floating crane in attendance and lifting out the Port Motor. The crane used to lift the motor out could lift a maximum 2000 tonnes. It cost 2100 euros per hour to hire.
Built 1967
Gross Tonnage 1999 t
Modified 1993
Classification GL + 100 A4 K
Length overall 55,00 m(Pontoon
Lifting Capacity 600 t
Breadth overall 25,00 m(Pontoon)
Pumping Capacity 1350 t/hour
Draft 2,50 m
BHP 1050
Propulsion: 3 x Screw Schottel Propellers in Kort-nozzles
The motor being lowered into the river barge for transport to LDW factory in Bremen. The motors had to be shipped back up to Bremen to the factory in order to open up along with the two from the crown princess in order to make two good ones which would fit easily and in the shortest time possible.
Due the new motors being slightly different in that the air coolers were mounted on the top and not the side as with the old motors we did not have quite enough head room in order to fit the motors. Thus we had to raise the deck head of thePem room which was the deck of the Inverter room and carried a considerable amount of electronic equipment within it. It was necessary to raise the deck head by some 6 inches. All the equipment above had to be supported to the upper deck head so that the deck of the inverter room could be removed and raised by 6 inches.
While the Motors were away being addressed we continued on with various works however we had to take the opportunity of making a snow man on deck. As you can see from the picture, not a shortage of snow !
The new motor’s being assembled in the LDW workshop. The new sections of bed plate weighed 4 tonnes each and thus added some 8 tonnes to each motor.
