I am trying to use a simple plane as a KActor with a Physical Material that emits a "ripple" particle system as the collision effect to make a large water surface (the FluidSurface won't work, it's too large for the simulation).

Thats works fine, except for the collision. How is it possible to make a KActor or any surface get collision information without blocking the KActors, so that the ripple particle system is emitted when the KActors pass through the water surface.

I have to admit that I have a limited understanding of the collisions in UDK. I found some infos in the UDN but I still have trouble to understand how to define what collides with what. I am used to Maya and its collision layers and I am not really able to make sens of UDK's system. For example if I set the RBChannel of a sphere KActor to BBCC_Untitled1 and let the Untitled 1 flag off for my watersurface KActor, why does the sphere doesn't go through the water surface... Doesn't the RBChannel define which channel the actor is in and the "RBCollide with Channels" define which channel it should collide with?

Maybe I am completely off track... The problem is that there isn't a lot of documentation about how does the RBChannel and the RBCollide with Channels work, so if you have any, can you please direct me ?