How to make parts can't collid with players and can collid with the vehicle that I want?

I wanted to create an amphibious USMC vehicle and I wanted it to be in terrian water so I decided to add a part that invisiable and can't collid with players but it can collid with the vehicle here is the question how to make the part can't collid with players but it can collid with the vehcile that I want Sorry bad English

Consider using 'CollisionGroups' to filter their collisions with other parts. The service is "PhysicsService" to use it within scripts.