Question

Why a steel ship becomes magnetized as it is constructed?

Answer 1

iron or steel is only magnetized when current is passed through it...
ship is magnetized because it has a superstructure,, during welding of ship enormous amount of current is passed through it and also it goes on and on path through the whole structure which aggregates the current up to thousands of amperes ,,,
as a result this current re aline all the molecules because of which they become a little magnetic and make the entire steel ship magnetic :)

Answer 2

Because steel is a ferromagnetic substance.

Step-by-step explanation:

A ship is build from number of plates joined together as a group of panels and block by welding.

A huge amount of welding is done for the construction of ships. During this a high ampere of current is required. As steel is a ferromagnetic substance, it has magnetic dipoles which tends to acquire magnetic behavior once being passed through electric current.

Hence when huge amount of current is passed through steel plates for the formation of ship, it becomes magnetized.