Well, to my mind, in a technical sense we're talking about square-rigged vessels.
If they are shaking then the vessel is sailing too close to the wind for them to draw properly. Either the yards should be trimmed or the course adjusted.

Refering to the pretty fair maid, I guess that she's showing a sailor all that she needs to, to gain his interest!! and if her bosom quivers like the top-sail of a ship sailing too close to the wind - well thats all we need to know!

Jake