127 HP. They can do the same method as the paint buckets, just spam the shit out of them. After weld, they flip em. EDIT: When flipped around. Its not as stable since I hit prop limit but thats an example if you equally make them buoyant.
Ah, this is where my stat list comes in handy.... I think the chair is fine as is (for now) because it takes a minimum of six (6) to hold up a single player. The buckets only need five (5) and they're smaller.