My plan is to submit a first version that is “good enough” in a few weeks. There are a few things that I still want to implement the release. In the meantime, I have greatly improved the performance of the buoyancy calculations. They are still done in blueprint, but now a lot more floating objects are possible at 60 fps. I will post an example soon of what is now supported. I think the buoyancy is now fast enough to be useful.
Objects that can sink and rise are already supported with the current buoyancy system. There is a public variable in the buoyancy component that controls how deep an object is submerged. Additionally, you can influence the submersion depth by adding a vertical force to an object.
I plan to implement shoreline support, but not for the first release.