Diesel engines in ocean going cargo ships

[Donald]

I was listening to a guy discussing the cargo ship that struck the bridge in MD and it's engines.

Couple of interesting things were mentioned.

1) The main diesel engine is connected to the propeller shaft. The engine itself can be run CW or CCW depending upon if you want to go forward or reverse. To change direction you need to stop the engine then start it in the other direction.

2) the engine is started by compressed air also requiring the generator to be running.

3). The cooling pump and fuel pump are electric powered and require the generator to be running. So the main engine will not run if the generator is not running.

4) The ship had 4 generators. Two pairs of two. The generators put out 6000 V and that was cut to 440V by transformer.

5) The presenter said the cooling pump, fuel pump and bow thruster all run on the 6000 V from the generator. I think he was wrong and they run on 440V.

 

[Gyro Gearloose]

The video I saw showed the bow thruster connected directly to the 6000V bus which in totally believable. As for the others it would depend on the pump speed and hp requirements. The plant where I worked had large slow speed motors 300-1000 hp that were all high voltage motors (4000 volts) to get the power output without being the size of a minibarn.

 

[BrendanC]

probably correct, higher voltage means less current which allows them to use smaller wire. the 440v is really only used for small machinery and lighting.

 

[Donald]

So with four generators plus an emergency generator one might guess that the problem was with the high voltage power board. The power board might be the single point of failure.