Originally Posted by carstendenmark
OP here - thank you so much for all inputs !
About dimming of a screen/display by a cover :
If not focusing completely on RED, but dimmed, how about a grey tinted acrylic
sheet cover ?
Then the colours are there, but the light is dimmed.
A neutral density filter is much nicer to use than red and allows the preservation of colour coded information. It can be a good choice in situations where you need detailed electronic information and are prepared to sacrifice some dark adaptation.
However, it is important to realise that dark adaptation is a slow process so even after not looking at the screen, the best levels of dark adaption will take around 15mins to recover.
The correct level of red light will reduce or even eliminate this lag, but the quality and ease of use and speed of information from the chartplotter
will be significantly degraded.
In a situation where detailed information that can be processed rapidily is required from the radar/electronic chart/AIS, then dull white light can be the best choice. However, sailboats travel at a slow speed so often it worth sacrificing high speed electronic data to preserve the best dark adaptation
Much depends on the circumstances, but the ability to have some electronic information while preserving the best dark adapation can be a very useful option and only red light will do this.