Can I add more boats on it？

[huangrunhui]

Can I add more boats on it？

[P3TE]

This simulator was designed with only ever one boat.

That being said, if you're willing to dive into the code and make some changes, you certainly can add additional boats.

Adding more boats will come with different amounts of difficulty depending on how high fidelity you want the boats to be.

Adding a static boat would only require you to add the boat model to the existing static models (buoys) and should be relatively simple.
Adding a dynamic boat that interacts with the waves will required you to add a new instance to the physics world and will require more work.
Having the additional boat(s) have meaningful image and LiDAR sensor readings will require additional render passes and require a lot of code changes.