When the mega container ship Dali struck the Francis Scott Key Bridge at 1:28 am on Tuesday, March 26, the world saw a remote video of a ship-wide power outage seconds before impact.
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I take issue with the statement “Dali was propelled by a single low-speed two-stroke crosshead diesel engine coupled to a fixed-pitch propeller.” Logic dictates that some sort of transmission device was placed between those two technologies. It is my understanding that the diesel engine spins and alternator that feeds an an electric motor that is connected to the propeller. The propeller shaft is the armature. That same arrangement has been in use on railroad diesel locomotives for decades.
MV Dali uses a directly connected MAN-B&W 9S90ME-C9.2 engine which is run in reverse for reverse propulsion. This arrangement is very common in Containerships.
Let’s not get ahead of the NTSB. While the press has advanced contaminated fuel as a possible cause, the on-going investigation has made no determinations. It will be some time before we understand why the Dali lost power.
While Dali may have instigated this article, the point is, any of us who run diesels can experience fuel contamination. I was overwhelmed to see all the types of additives that are out there. If I used them all, I wouldn’t have any room in my tank for the diesel fuel! So my question is: What one additive is best for maintaining a contaminant free fuel system and affected engine components?
My source for this info is a harbor pilot friend who undocked the MV Dali about two days before the Key bridge collision. He had docked and undocked her several times.
The Dali has a single large in-line diesel, as noted. There is no ‘neutral’. When the engine is turning, the prop is turning also. Reversing the engine (and proceeding astern) is done by stopping the engine, changing over the gear to select ‘astern’, and restarting the engine using compressed air. Whether the engine is then run in reverse is certainly possible. My point is that it is not instantly reversible.
Contaminated fuel is certainly a possibility. Apparently there are also a number of shipboard computers and it is possible that a cascade of failures begun by the failure of the main propulsion engine occurred, as successive systems shut down.
The pilot, who had very little time to react, was able to drop anchor, get off a MayDay call, and contact the MTA police to get all the traffic off the bridge- except for the road crew; six of the eight in the road crew died, which is tragic. But for the pilot’s action, more people might have died. That seems to me to be an admirable performance.
Interestingly, my friend felt that a tug escort should have been present and possibly cabled to the Dali. When the Dali left the dock, she was pushed off the dock by tugs, into the channel, and the main engine was then started. Apparently the main engine ran for at least a minute or two as she had accelerated to eight knots before the collision.
Like everyone here, I am very keen to see the findings of the NTSB and the USCG.