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Comment by eps | Hacker News Reader

Wouldn't the burden of steering off collision courses be on these shadowy hard-to-spot ships then?

Yes, the tanker belongs to "Restricted in Ability to Maneuver", which means they have priority over pretty much anything. You can't ask them or expect them to detour to avoid you, you must avoid them.

That's not correct - according to the Collision Regulations, simply being a large ship does not make you "restricted in ability to maneuver." That definition is reserved for vessels carrying out an activity which restricts them from altering their course, such as dredging or mine clearing. A large oil tanker may be "constrained by draught" in a narrow channel in which case it does indeed have right of way over smaller vessels, but larger vessels will be constrained too so "priority over everything" becomes a pretty meaningless concept as everyone will have it.

In open water, large vessels like that give way to smaller vessels when appropriate all the time.

https://www.navcen.uscg.gov/?pageName=def3g_RAM https://www.navcen.uscg.gov/?pageName=def3h_CBD

Nonetheless, I'd expect a far more agile battleship to be able to move itself out of harm's way.

It's ridiculous that they're out there unlit and not broadcasting their position, and somehow not 100% liable for the damage caused by such behaviour.

Especially considering that their sensor suites must be orders of magnitude more powerful than commercially available civilian equipment.

Primary navigation radar gives away your position, as does active sonar, in the same way that AIS does. If they have the latter off, it's not unreasonable to assume they also have the others off.

Passive sonar would pick up a tanker if the engines are running fast enough or the ship isn't particularly streamlined (which tankers invariably aren't) so this is probably a failure of communication.

Crew on the bridge with NODs would seem to be a no-brainer in those conditions, at least.

Seems like the naval vessels should be using passive radar detection as well, if they're not already. That wouldn't protect them from everything, but it should catch all of the big commercial vessels, right?

The tanker was broadcasting its position. That's how we have this nice visualization. I don't understand why you are talking about active systems. They should just have listened to AIS messages.

Likewise also don't understand why the article goes on and on about more clever ways the collision avoidance system could be programed. No collision avoidance system can help you if the operators of the stealthy war-machine drop the ball.

Oh, I wasn't aware you can receive other ship's AIS position updates while your own system wasn't active.

Even in that case, it's the same as the passive sonar example I illustrated: the ship is there and you can see it, but they didn't avoid it anyway. Failure of communication.

And you know, turn on the lights if necessary...

The navigation lights should be on. They are not immune to the ColRegs (but they can add more lights and dayshapes if they want as long as they don't add anything confusing).

I don't understand how, after three accidents, they don't have a policy of careful watch in an area like that. Something still doesn't smell right with the info we're getting.

My theory is this is a covert operation by the Chinese to disable the U.S. 7th Fleet, one merchant ship collision at a time. :)

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