The bird's average speed is 33 mph (29 knots). Cargo vessels tend to cruise at about 18-25 knots, and many move more slowly.
There's little direct traffic between Alaska and Australia. Shipping lines are visible through their emissions trails, as in this Nullschool link showing NO2 concentrations, from May of this year. The long lines are shipping lanes. You'll note these from Panama to New Zealand, tracking along the Western US coast and Alaska along the Great Circle route to Japan and China, and past Papua New Guinea, among other notable routes:
The data recorders would also likely note any marked variations in travel speed or direction. Again, ships tend not to cover the routes flown by Godwits.