Package layout

Package	Purpose
bluerobotics_parts	Every part — mesh, delivered SDF and xacro macro. Shared by all vehicles
bluerov2_description	BlueROV2 assemblies, RViz; pure description, no simulator code
bluerov2_gazebo	Composed Gazebo model (thrusters, hydrodynamics, sensors, grippers), world, launch and ros_gz bridge
blueboat_description	BlueBoat assemblies, RViz; no simulator code
blueboat_gazebo	Composed BlueBoat model (twin thrusters, hydrodynamics, echosounder), surface-water world, launch and ros_gz bridge

The split follows a convention common to ROS robot repositories: description packages hold geometry and frames only, gazebo packages compose them with simulation behavior (plugins, sensors, worlds, bridges), and the shared parts package feeds both vehicles.