metaphor is that of passengers in the life-boat of a sunken ship.
To sail under false colours — to pretend to be what one is not; sometimes, to pose as a friend and, at the same time, have hostile intentions. The metaphor is that of an enemy ship that approaches its intended prey showing at the mast the flag ("colours") of a pretended friendly nation.
To show one's colours — to betray one's real character or intentions. The allusion is, once more, to a ship showing the flag of its country at the mast.
To strike one's colours — to surrender, give in, admit one is beaten. The metaphor refers to a ship's hauling down its flag (sign of surrender).
To weather (to ride out) the storm — to overcome difficulties; to have courageously stood against misfortunes.
To bow to the storm — to give in, to acknowledge one's defeat.
Three sheets in(to) the wind (sl.) — very drunk.
Half seas over (sl.) — drunk.
Though, as has been said, direct associations with seafaring in all these idioms have been severed, distant memories of the sea romance and adventure still linger in some of them. The faint sound of the surf can still be heard in such phrases as to ride out the storm or breakers ahead! (= Take care! Danger!). Such idioms as to sail under false colours, to nail one's colours to the mast (~ to be true to one's convictions, to fight for them openly) bring to mind the distant past of pirate brigs, sea battles and great discoveries of new lands.
It is true, though, that a foreigner is more apt to be struck by the colourfulness of the direct meaning of an idiom where a native speaker sees only its transferred meaning, the original associations being almost fully forgotten. And yet, when we Russians use or hear the idiom первая ласточка, doesn't a dim image of the little bird flash before our mind, though, of course, we re-