In trucker forums, I can see drivers referring to their trucks by pronoun “**she**”. Similarly [a site](http://www.thebomber.com/history/) about an older airplane writes about “restoring **her**”.

I would expect using “**it**” for all things (which are not persons).

What is the logic here behind using “she” instead of “it”?  

In what other cases (not referring to people) is this applied?  

Would using “it” sound unnatural in these contexts?

Note: there is already a similar question if a car should be “he” or “she”, but this one is sligthly different.