Buoyancy for multiple welded physics static meshes

Hi, I have a water plane, and I have a boat building and welding system, I build a boat, if the simulate physics is false, it stays in place, if true + set physics linear velocity it floats very good, but if I stand on it, it flies away.

Im having the same problem with my Player Blueprint (that has a capsule collider) and my physics actors in the level flies off as soon as I use Set Actor Location.

Please write here if you find any solution to this problem.

Thanks