4:10 PM: Thanks to Eli Barlag for the photo. That’s the Ready Reserve Force cargo vessel M/V Cape Hudson, which arrived in Elliott Bay today after sailing up from Tacoma. It’s a 750-foot roll-on/roll-off cargo vessel, 41 years old, based in San Francisco and often chartered for military operations like Pacific Pathways. According to a Maritime Administration social-media post from earlier this year, Cape Hudson is still part of that”mobility exercise, taking on and discharging cargo at domestic and international ports … an annual operational deployment exercise designed to determine the best methods for planning, preparation, execution, and ordering of craft to move troops and equipment.”
ADDED MONDAY MORNING: Without docking in Seattle, Cape Hudson sailed on this morning, currently shown on MarineTraffic.com as northbound in Puget Sound.