Question: How can I reduce naval movement range on the campaign map without affecting land movement?

Details:
I’ve been editing campaign movement values and testing various DB tables and Lua scripts. I discovered that land and naval movement are tied together — changing one affects the other. My goal is to reduce how far armies can move on water (rivers or sea travel lanes) while keeping land movement normal.

I’ve tried adjusting campaign_movement_range, character_movement_modifiers, and even terrain types, but nothing isolates naval movement. Has anyone found a way to apply movement penalties or remove sea travel bonuses specifically for naval movement? Lua-based solutions are welcome too.