7 ms·

Genuine question: All the commercial vessels continually broadcast their position, speed and bearing, right? Even if the military vessel does not do so, it sho

Genuine question: All the commercial vessels continually broadcast their position, speed and bearing, right? Even if the military vessel does not do so, it should be able to receive all commercial vessels telemetry... So how can it possibly crash into one?

iramiller 9y ago
Along the same lines all these ships have sophisticated radar systems and can generally track where other vessels are regardless of whether or not they are broadcasting their positions. No one would expect such niceties during wartime.
jandrese 9y ago
Exhaustion and inexperience according to the article. You try navigating safely on 3 hours of sleep over the past three days doing a job you weren't trained for.
soneil 9y ago
> Genuine question: All the commercial vessels continually broadcast their position, speed and bearing, right? Correct. AIS uses regular broadcasts, it’s not challenge-response. > Even if the military vessel does not do so, it should be able to receive all commercial vessels telemetry... Correct. Having an AIS receiver instead of an AIS transponder is a very typical setup for smaller sailboats or daysailors. If they’re not ready for the cost, complexity or power budget of a transponder, they can still pick up a receiver+plotter for $200, which will get them a little lcd with a map of traffic, CPA alarms, etc. Another $200 turns it into a transponder so that you show up on the other guy’s screen too. > So how can it possibly crash into one? The million-dollar question I guess. We manage to avoid it with a $400 radio and one pair of eyeballs on deck.
cconover 9y ago
Yes, AIS is utilized by all ships, and even though military vessels are permitted to not broadcast in the clear their AIS data, they can still receive other ships' AIS broadcasts. That being said, you still need competent mariners on the bridge who can look at their instruments - AIS, ECDIS/chartplotter, radar - as well as use their own eyes looking out the window to interpret that information and made a prudent decision. As the Navigation Rules[0] are written, all vessels must maintain a proper lookout, and electronic systems by themselves are not a substitute. Once a mariner determines that risk of collision exists, regardless of whether they are the stand-on or give-way vessel, they must take sufficient action to avoid collision. Additionally, depending on what the situation between the two vessels is (meeting, crossing, overtaking), they are required to exchange sound signals to indicate their maneuvering intention and acknowledgement by the other vessel of that stated intention, or may make those arrangements by radio in lieu of sound signals. All of that requires prudent, competent mariners who can recognize what is happening around them, and their responsibilities in any situation involving another vessel. [0] https://www.navcen.uscg.gov/pdf/navRules/CG_NRHB_20151231.pdf https://www.navcen.uscg.gov/pdf/navRules/CG_NRHB_20151231.pd...

iramiller 9y ago

Along the same lines all these ships have sophisticated radar systems and can generally track where other vessels are regardless of whether or not they are broadcasting their positions. No one would expect such niceties during wartime.

jandrese 9y ago

Exhaustion and inexperience according to the article. You try navigating safely on 3 hours of sleep over the past three days doing a job you weren't trained for.

soneil 9y ago

> Genuine question: All the commercial vessels continually broadcast their position, speed and bearing, right? Correct. AIS uses regular broadcasts, it’s not challenge-response. > Even if the military vessel does not do so, it should be able to receive all commercial vessels telemetry... Correct. Having an AIS receiver instead of an AIS transponder is a very typical setup for smaller sailboats or daysailors. If they’re not ready for the cost, complexity or power budget of a transponder, they can still pick up a receiver+plotter for $200, which will get them a little lcd with a map of traffic, CPA alarms, etc. Another $200 turns it into a transponder so that you show up on the other guy’s screen too. > So how can it possibly crash into one? The million-dollar question I guess. We manage to avoid it with a $400 radio and one pair of eyeballs on deck.

cconover 9y ago

Yes, AIS is utilized by all ships, and even though military vessels are permitted to not broadcast in the clear their AIS data, they can still receive other ships' AIS broadcasts. That being said, you still need competent mariners on the bridge who can look at their instruments - AIS, ECDIS/chartplotter, radar - as well as use their own eyes looking out the window to interpret that information and made a prudent decision. As the Navigation Rules[0] are written, all vessels must maintain a proper lookout, and electronic systems by themselves are not a substitute. Once a mariner determines that risk of collision exists, regardless of whether they are the stand-on or give-way vessel, they must take sufficient action to avoid collision. Additionally, depending on what the situation between the two vessels is (meeting, crossing, overtaking), they are required to exchange sound signals to indicate their maneuvering intention and acknowledgement by the other vessel of that stated intention, or may make those arrangements by radio in lieu of sound signals. All of that requires prudent, competent mariners who can recognize what is happening around them, and their responsibilities in any situation involving another vessel. [0] https://www.navcen.uscg.gov/pdf/navRules/CG_NRHB_20151231.pdf https://www.navcen.uscg.gov/pdf/navRules/CG_NRHB_20151231.pd...