In some places it's imperative; either to keep moisture out or protect the decks from the sun's destructive UV rays.
Even if you operate in the most ideal place, you may still find some kind of cover necessary.
Covers can keep dust and debris from blowing into the boat.
Spiders are less likely to crawl in and set up shop.
If a boat is covered it may discourage passersby from nosing around - knowing they'll have to go to more trouble to do so.
A good cover also helps keep birds from pooping on, and cats from peeing in the gondola.
I've seen some pretty impressive variations on the gondola cover theme, and this one ranks high on the list.
Most gondola covers are meant for quick and easy removal (even though they are often just tied to one side), but the owner of this gondola appears to have long-term storage in mind.
For daily use, this would not be my first choice, but it would be great if I had to leave my boat unattended for long periods.
The canvas attaches at the rail, stretching over a series of bowed battens (which kind of remind me of an old covered wagon), and looks like it's no small task to put on.
I'm guessing the guy who created this masterpiece is quite proud of it.
I'm also guessing that it wasn't cheap - but then really, that's a small price to pay to keep cats from peeing in your gondola.