"The Submarine may not be compatible with the currently selected content packages, because it requires the content packages EK | Gunnery, Better Glass, POwerful Sonar. Are you sure you want to choose the submarine?" ---

Is stated when trying to host a game using this submarine while having the 'required mods' active. I suggest adding the mods to the 'required mods' part of the Workshop page so they're linked and are automatically downloaded, or at least include a URL with each of your required mods. Or if a specific mod order is needed, include it in the description.

Currently broken and unable to use.