Sorry, but I cannot see a sail from a sailboat when I look at this. It is clearly curved only like a woman with a C cup could be. It is a boob. And so was the architect that thought he was designing a sail when he penned this.
A real sail never quite traces an outline like that under full or partial wind. Any sailor would agree. This is what sails look like:
Or even like this. Note the shape of the curve. In geometry it is referred to as a catenary. The parabolic arch traced by a line falling under a natural force. Like a suspension bridge's cable against gravity, or in this case a sail against the force of the wind.
Here's hoping the owner of the unit closest to where the nipple should be, has the moxy to stick a giant red parasol on the balcony for the summer months.
Furthermore... If you were trying to evoke the feeling of a sail against the water... Why choose green glass for the sail? Why not use fritted ceramic glass, like Festival Tower used, for the sail and blue for the water. It would better emulate the look of a sail... especially IF THEY SHAPED IT RIGHT.