emma maersk port said

The Emma Maersk at Port Said, Egypt

The EMMA MAERSK suffered a flooding incident in February as it was getting ready to transit the Suez Canal. As reported earlier, water entered the vessel through a damaged stern thruster. The flooding was initially contained in the shaft tunnel, however, the Danish Maritime Authority’s investigation report just released notes that once the pipe tunnel was full and the pressure equalized with the depth of the hull, the water found a weak spot, cable penetrations through the water-tight bulkhead.

emma maersk flooding

According to the Danish Maritime Accident Investigation Board (DMAIB),”the main technical sequence of events were a break-down of the forward stern thruster causing a major leakage into the shaft tunnel, a collapse of the watertight integrity of the bulkhead between the shaft tunnel and the engine room, primarily caused by non-effective cable penetration sealings and some undesirable properties of the bilge system and the emergency bilge suction from the engine room. Throughout the course of events, all officers and crew members were constantly disturbed and highly stressed by the sound of countless alarms, which made it extremely difficult to concentrate on the many challenges that appeared.”

Simply put, penetrations are holes in a watertight bulkhead. A penetration can be to permit movement by crew, cargo (think car carriers), pipes, portholes, propeller shafts and electrical cables. Each kind of penetration has to be sealed, whether by a watertight door, shaft seal packing or other way. The sealing of the cable penetrations on the EMMA MAERSK were not able to withstand the water pressure of a flooded shaft alley.

At about 2205 hours, a 3rd engineer, who was standing at the aft part of the main engine watching the situation develop, became aware that water unexpectedly began flowing from a 440 volt AC outlet at the port side of the engine room some five or six metres from the water-tight bulkhead.

As the 3rd engineer investigated this unexpected scenario, he heard a sudden blast and saw one of four cable penetration sealings in the water tight bulkhead give way to the water pressure followed by a massive ingress of seawater. A few moments later, the other three cable penetration sealings also failed which resulted in an even larger ingress of water into the engine room.

With a draught of approximately 15.1 metres, the entire space of the shaft tunnel and the emergency exit, leading vertically from the aft part of the shaft tunnel to the cargo hold, had been filled by seawater. The water pressure at the propeller shaft sealing and cable penetrations of the watertight bulkhead was therefore equal to a water column of appr. 8.9 metres (Note: 29 feet below sea level!).  – DMA Report

The accident report is a great read and I dare say a must read for every engineer and Captain/Chief mate. I especially recommend reading the section covering the events in the engine room. Then read up on the section covering the sealing of the cable penetrations, or more appropriately covering how the cable penetrations were improperly sealed by using parts meant to seal for gas and fire, not watertightness. There is no telling how this accident might have ended had they been at sea. Congrats to the crew for dealing with a very dramatic incident.

So how many of you are going to take a closer look at the cable penetrations on your ship the next time your sailing?

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  • waynep71222

    WOW!!! great read.. brings up all kinds of questions. 
     i would imagine that every water tight packing separator is going to need to be inspected.  with at least a self actuating center punch to see if its plastic or metal. that would be a quick and easy way as you only have to access the end of the separator where it overhangs the mounting ring.

    i wonder how tight the ventilation doors seal in figure 12 . and if they close against a single sided ridge to seal them or if a redesign is needed and a bend across the middle then profile milling the blade.. so it can only rotate 88 degrees closed as the angled edges will impact the ID of the tube sealing it like a carburetor throttle blade. 

    i have a better idea for the water tight shaft seals shown in figure 13 and 14.  Forshida seals.  or V seals..  made with a wide flange. spit so they can be removed and replaced on the prop shaft when they wear..  one on either side of the water tight bulk head.. would work far better than a packing seal that depends on shaft alignment.  the hole in the bulk head could be several inches larger than the shaft od.. and the seals ride outside that a significant amount. 
    the design would need to have enough section thickness to prevent a blow thru of the seal if there is water ingress on one side of the pair.. 

    there is going to need to be significant gussets added to the sides of the mounting flange welded into the thruster tubes shown in the failure in fig 41.

    perhaps some vibration indicators on the thrusters also.. to monitor for missing blades. 
    i personally wonder if the rear thruster tube is flat against the sides of the hull.. and if during a docking when the thrusters are used to hold the ship against the dock. if the sides of the dock are totally solid and flat.. that would have blocked most of the inlet flow and created extra stress on the blades..  covered under the term cavitation on page 44 paragraph 9 from the fairings.. that might have blocked the inlet. 

    figure 42 thru 49 show the blade fatigue and fracture areas.  adding material to the root of new production blades that creates more of a diamond pattern that keeps the root foil shape closer to the center of the 3 bolts in the pattern..  with that ridge extending up farther into the blade to add structure to reduce flex at the root as shown. 

    the thruster supporting plate shown in figure 38 on page 35   figures 51 thru 55 need a plate doubler in that area.. even if the edge that faces the propeller is beveled for blade clearances

    that’s the heavy side of the motor  with the prop on it .  loss of a prop blade is going to cause this again… 
    wayne.   forward thinking saves lives.

  • roperin

    Thats about the most thoughtful and complete comment there could be on this incident.  I’d like three of these people on my team.

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