Thanks for the tip and photo! That’s the Zhen Hua 23 passing West Seattle, carrying four China-built port cranes southward. Usually there’s a big advance alert about this kind of thing, but so far all we’ve found is that the Zhen Hua 23 is on Monday’s schedule to dock at the Port of Tacoma’s WUT (Washington United Terminals) terminal. (Terminal 5 in West Seattle is due to get cranes for the second modernized berth, but that’s still some months away.)
ADDED: Here’s the WUT announcement from when these cranes were ordered.