I’ve been wondering about the possibility of a ship simulator somehow being embedded or linked to P3D. A lot of things would obviously have to be reworked, like coastlines, water dynamics, and weather simulation and it’s effects on the sea but my question is would it be possible or would it be necessary to build a standalone sim and somehow link it to P3D? Like getting the aircraft and airports from P3D but create an environment for ships like we have for airplanes? Just curious.

Depending upon the package's requirements (any DLLs), there's nothing to stop someone from using a FSX watercraft in P3D4. After all, P3d4 does come with a submersible ship out of the box. Proper water based data would need to be extended from the limited areas shipped with P3D4.