Is it balanced?

No.
Let's compare it to the 4th level spell from 3.5 edition(3.5e) (before 5th edition(5e)), from the spell compendium, called Raise From the Deep.
That spell raised a specific ship you had to know up from any depth to above sea level. It did not do any repairs. It did not crew the ship. It just raised the physical body of the ship above sea level for one hour per level. If you could repair it in time and crew it, great. If not, it would sink back.

Your spell is of the same level and does a lot more.
Given that Raise From the Deep is from 3.5e, and 5e kept almost all spells but rarely made them more powerful - it mostly kept them the same or made them last a shorter period of time - I would say it is not balanced against the other spells in 5e. As a matter of fact, most people I talked to found Raise From the Deep to be too powerful in 3.5e. It was hard to compare objectively, because it did something unique, but most people said "You can do that with a 4th level spell? That's not okay..."

Does it add anything fun to the game?

That's a in relevant question related to your question.
This spell is not used "against" anybody. Not against players, not even against NPCs. So is "balance" really the unit you want to measure it by? I would advise you to find another point of view: is it fun?

Diving down to sunken treasures in rotten ships' carcasses is a great adventure. Rough seas, monsters and dangers you normally don't face in your standard adventure. Gold in chests, easily lost if you don't take care when you bring it up to your own ship. And your own ship? Is it in danger when you lead your most experienced heroes underwater with no contact? A sunken ship is an adventure. It's dangerous, it's adventurous, it's full of what we love to play for. Even keeping your ship from sinking is a great adventure on its own. Finding a shallow cove/bay/coastline to beach it and make repairs, protect from storms and predators on the island, all a big adventure.

So why have a spell to skip the fun part?

I could easily see a spell "free-princess-from-dragon". It would probably not be overpowered for 4th level, because it is so very specific and situational. But... why have it? Isn't the princess-saving the whole point of why we sit around the table? Do we really want our fun be a 3 second wizard spell and nothing more?

TL;DR

The answer to your question is "no, it's not balanced" but the solution is not to balance it. The solution is to scrap it and find a way to make the sunken/sinking ship an adventure instead of a matter of a player flipping through their books' pages to find what it takes to get the ship back.