Negate PostProcess/PhysicsVolume ?

Hi All,

I need a fresh idea here. I’m probably not thinking right because of the water simulation math I’m (still) working with. But I finally have a solid basis and a rowboat into the level.
The issue is that the rowboat dips into the post process and the physics volume.
mostly just to give me head-hakes.

Does anyone have any idea of how to exclude a movable area from a post process/volume/brush ?
Did not find much on this but my search terms may be the issue here.