‘Safety of navigation’ anyone know?

[Sean_B]

On 6/23/2019 at 4:00 PM, chengkp75 said:

Even indirect, ambient lighting will affect night vision, so as long as the light is shining outside, whether directed at the bridge, or just adding to ambient lighting like a city's lights do, will affect night vision.  Most cruise ship bridges will have shades on any aft facing, and many side facing windows to prevent the ambient light spillage from the side of the ship affecting their vision.  The only other way to avoid this "light spillage" would be to have all the forward facing cabins behind and below the bridge by a considerable margin (i.e. having the bridge jut out forward of the cabins), and even then it would degrate night vision to an extent.  Those who have never experienced the extreme dark of night at sea (and a cruise ship is anything but dark), don't understand how a single small light can affect your ability to see dim objects in the dark.

 

I think we are probably some of the few who have experienced the absolute darkness of the night at sea. Me: former Officer of the Watch in the Navy.

[coevan]

 night sails are quite magnificent, of course with cooperating weather. 

Edited June 24, 2019 by coevan
sp

[chengkp75]

Maybe a little science will dispel the "ignorance":

 

https://www.researchgate.net/publication/259425341_Night-time_Lookout_Duty_The_Role_of_Ambient_Light_Levels_and_Dark_Adaptation

 

Or how about from one of the classification societies that most cruise ships use (if you don't know what a class society is, google it) to obtain their certificate of seaworthiness:

 

https://rules.dnvgl.com/docs/pdf/DNV/rulesship/2011-01/ts608.pdf

 

If you don't want to better yourself reading all about the rules for nautical safety, just look at rule Section 3, Rule C202:

 

"202 During hours of darkness; the lighting provided to discern control devices and read labels and markings shall preserve the night vision of the OOW. It shall be possible to dim down the illumination intensity to nearly zero. Guidance note: Except at the chart table, red light or filtered white light (CIE coordinates x and y equals 0.330) should be used whenever possible in areas or on items of equipment requiring illumination in the operational mode, including bridge wing instruments. Provision should be made to prevent red lights from being visible from outside of the ship."

 

The rules also state that workstation illumination on ship's bridges, at night should be by red light of 20 lux intensity, which is actually less than 1/2 of a watt.  I guess they are showing their ignorance that ambient lighting, even at extremely low wattage, can affect the safe navigation of a ship.  Yeah, no one in the entire maritime industry believes that night vision is important.

[chengkp75]

1 hour ago, Elaine5715 said:

Considering the professionals continue to respond, well, professionally, whereas some of us would not be so pleasant.  

I'll admit, I'm getting very close to the line with professionalism.  Step back and take a breath.

[Elaine5715]

7 minutes ago, chengkp75 said:

I'll admit, I'm getting very close to the line with professionalism.  Step back and take a breath.

OMG, Chief quoting me?  I may faint.  Woot, if I do, I will test my night vision...

[Lottacruises]

13 minutes ago, LostPuppy said:

I was a crew member on a nuclear sub for several years. The control room on the sub is "rigged for red" at night.  The logic behind this that if the sub needed to do an emergency surface, bridge personnel (look-outs, OOD) could quickly go to their posts and have effective vision.   Night vision is also needed for any periscope depth operations.

 

While the rest of the sub (outside of berthing) is always lit with florescent lights,  walking into control was like going into a black hole.  The only lights are from the gauges and even those are turned way down.  

 

And then there's that... Lol

 

Thanks for explaining these things to us guys. Some of us like to learn!

[crooooze]

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Edited June 27, 2019 by crooooze