"Ships are 'she', except in the American navy, where littoral surface combatants are 'he'", or "...except in the British navy, where submarines are 'he'", something like that, isn't it? Guess I'll only talk about "the vessel", which should pretty reliably be "it".

> Plurals and articles seem to trip up many non-native English speakers. The rules for these things are quite intricate and riddled with exceptions, and if you write a page of prose and make a single mistake with a plural or an article, a native English reader will instantly know you are not a native speaker, even if your meaning is understood.

Fortunately not so bad for speakers of German and the Nordic languages, which work rather similarly. (Germans usually give themselves away by using the compound in stead of simple past tense.)

> Example: "if you write page of prose and make single mistake with plural or article, native English reader will instantly know you are not native speaker."

The canonical example seems to be the Slavic languages, above all Russian.