The Naval Transports, which can be seen on the Screenshots above are part of my Mod: FBP New Techs.
The Mod itself is still in development but it is available on my Github Repository as an Early Access.
I already know that Naval Transports are not really supported by the Game itself.
There are a few Issues which makes them a little bit tricky to made.
For Example if you want to unload your Landunits from these Naval Transports.
It can happen that a few Units will be located below the Land / Ground Layer of the Map and will be destroyed. It is not perfect at all, but overall these Naval Transports exist.
Even the Landtransport from Brewlan has this Issue sometimes and is still a really cool useful Unit
But for the Issue itself there is no way to fix this as far as I know.
I have several other Concepts in my archives for Naval, Hover or Landunits, which I want to try out in the future.
Maybe these ones will work better in general. But since my main Development Progress is currently focused on FBP Orbital (a new upcoming Space related Mod with Spaceships, Spacestations and more) these Naval Transports are the only ones.
Of course Air Transports are very useful in several aspects of the Game.
But even in Real life there are many other Variations of Transports. The main reason why I have add Naval Transports is to add more Variety to the Game.
Basically Air and Naval Transports have thier own Advantages and Disadvantages and are useful on different Situations. The next point was the topic of the addition of Naval Transports into the Game is old and starts after the Release of Supreme Commander. And the last thing is why not it is still the decision of the player to use them or not.