That’s a good idea. Are you talking about surface or underwater? I guess you mentioned ships, so that’s surface. Either way, I THINK there isn’t a ubiquitous one like turtlebot. People mentioned having more accessible inexpensive marine robots for education at the ICRA marine workshop in 2021, but I don’t know if there is a platform that educators start beginners with.
That said, the features you mentioned – a simple environment with thruster and hydrodynamics for the purpose of testing controls – it exists. The LRAUV simulator mentioned in the Community Meeting fits that bill well. It is an underwater vehicle though.
Here’s the example world file in the modern Gazebo: https://github.com/gazebosim/gz-sim/blob/gz-sim7/examples/worlds/auv_controls.sdf
It is very barebone, just the vehicle model and a few plugins. You can see it has hydrodynamics and thrust, both are built-in features in the new Gazebo. The controllers to illustrate the example are very simple, and that’s where you can substitute in your own controllers. It is independent of ROS though, so you’ll have to set up the ROS hooks.
As for surface vehicles, with ROS integrated, there are less barebone environments, like the MBZIRC simulation in ROS 2 and modern Gazebo. The VRX simulation is also being ported from Gazebo-classic to modern Gazebo. You can see the recorded slides about them in the Community Meeting.