Great work/autism fellow anons! I'll add my 2 bits. Talked to friends on Whidbey. They didn't see the launch but concur that it looks like it came from Skagit Bay. A line drawn from Hansville to Mt Baker is roughly NNW. If it came from west of Whidbey it would be due north of Hansville. The track looks to be between those 2 lines and the only saltwater body is in or near Skagit Bay. Also a while back people around Holmes Harbor (south of Skagit Bay) were bothered by a loud low freq hum. They couldn't find any source on land and there were no visible vessels in the harbor. I suspect it was the Navy experimenting with UW sonic weapons and/or UW comm's. Pretty sure there's been subs in that area before so I wouldn't be surprised to find subs between Bangor and Oak Harbor.