Check out the Skydome blueprint, looks like the color is fed from a curve.
Current status of the upcoming “ships” update:
It’s almost ready, there a couple of things I have to clean up and make a bit more “modular” first, so you can easily add and configure your own ships/boats.
-Networking is all setup, all done via BP and nicely commented out (although synchronization is still WIP and probably not perfect, needs more testing)
I had to make a custom player controller in C++ though (to solve a problem with possession, basically the ship got de-spawned when a player it disconnected or exit the game while driving it) special thanks to for helping me figure out how to do that 
-Ship health and damage is implemented (nothing too fancy, just a simple health bar made in UMG and then sinking via density override), you can totally have a little naval battle 
Ships can be respawned after they are destroyed, there is a respawn time variable.
-Particle hit when hitting water, ice (icebergs) and wood which also catches on fire
-Added ambient sfx.
-Added snow, which can be toggled in Skydome BP.
-Cannons which can be fired individually by a player next to it or all at once when driving the ship.
You can add and “link” as many cannons as you like to a ship.
Each cannon has reload time and damage variables.
-Two ship blueprints.
The first one is pretty simple… forward speed, steering speed and buoyancy settings.
The second one is the “per-poly collision” one, I might post some notes after I release the update to explain a bit how it is done, it’s a little more complex.
Funny thing is that the per-poly collision ships seems that can be much more efficient perfomance-wise compared to convex collision with many primitives