It is just wrong, imprudent and dangerous to think you need to stay out of their way.
I couldn't disagree more. You MUST have intended to put a "NOT" between "dangerous" and "to think". While the Rules do specify the responsibility of the "stand on" vessel, no where in the Rules does it say you should've use common sense. Small boat skippers must assume that big ships are not as maneuverable as they are and that common sense dictates you should stay out of their way. That said....
One thing, though, is to realise they can't work out what you are doing easily, so Minnes 10 degree change of course would not have registered at all. For them to see it try 40 or 50 degrees. Hold that for a few mins then come slowly back to the correction you want.
Couldn't agree more. When "messing" around with big ships make every move early and very obvious. Big course changes are the order of the day.
One of the very nice features of AIS is that once you designate a contact for tracking, the system will tell you if he's changed his rudder angle. On more than one occasion I've "communicated" with an overtaking merchant ship using rudder angle alone. E.g., he's approaching from several miles astern and the CPA is a hundred yards or so. When he's a mile and a half or so away with little or no change in the CPA I will alter course 20-30 deg. to open the CPA. I watch his rudder angle and very often I see him turn opposite of my course change to open the CPA even further. Five or ten minutes pass and we both resume our original courses. No need for a radio call...he could see what I was doing....me likewise. If at any point in this "silent dance" it is not clear what's happening, I'm on the radio and we work it out...usually with me volunteering to stay out of his way.
But as I said in the original post, the photo shows a huge clearence. I would be very comfortable at that passing distance.
I'd agree the photo shows a very acceptable passing distance. Probably the most useful feature of AIS is knowing what the CPA is when you're still a mile or more apart. At two miles a 400 yard CPA can appear (visually) like its going to be much closer.
When big ships are a long way off (several miles) it's often very hard to judge the relative motion. The change in bearing often doesn't become obvious until you're closer to them.
All that's been said about trying to figure out where they're going and why they may be altering course as they are is good. You shouldn't think they're "messing" around. If professional mariners mess around they put their license, and therefore their livelihoods at risk.