Ok, so I know there are a lot of these topics out there but none work, I’m building a boat but I float when I’m between those bumps. I tried doing the Precise Convex Decomposition, but it never did anything to help, I tried splitting the models up, but there sizes even with auto resize off formed awkwardly. So if you have any ideas on how to fix it please do post.
I’m guessing you mean your character stands off the surface when they walk up or down the ramp sections of the deck?
You can use the Plugin Mesh Optimization Tools - Roblox by Clonetrooper1019 to show the Decomposition Geometry.
Meshparts and Unions will use a percentage type of system to figure out the DG, so if you have a huge wall and put a Robloxian size door in it then it probably will block the player.
Even worse is how Meshes and Unions ‘fill in’ concave sections like you’ve noticed.
I’d be tempted to try splitting your Mesh into 2 sections in a straight cut horizontally at the lower deck line. Keep the lower deck flat surface in the bottom mesh leaving the wedge ‘railings’ in the top Mesh and the majority of the hull in the bottom mesh.
Try to use wood material and make mesh uncollidable and add wedge welded to mesh so that u can adjust how much boat must sink.