You can trust that firm; the partners are in ballast all right.
in ballast(of a ship);carrying only ballast
main ballast tank
When big cargo ships are traveling in ballast, that is, without any cargo, they often carry tanks of water in their holes to make them sink far enough into the water to be stable.
Preliminary study on the species composition and abundance of phytoplankton and affecting factors in ballast water of ships from outside Fujian,China