LED's in navigation lights will change their color.

[cowpat]

I have searched for this subject without success. That is the GREEN light turning a definite BLUE ....So am asking if anyone has had this interesting problem.? I know it is to do with the spectrum composition of LED light.
I am interested because the manufacturers of navigation lights must be well aware that this happens and anyones thoughts on it would be appreciated.
I rectified mine very quickly by putting some Green acetate sheet inside the lens. Chris.

 

[awol]

Which bulb is this? It took a lot of R&D to produce blue (and hence white) LEDs; greens were around for a long time. Perhaps you could patent this development?

 

[Lon nan Gruagach]

Sounds a bit bizzare really, since LED colours are defined by the chemicals in them, which will not change.
It would be very VERY interesting to see a picture of an old and new one side by side...

 

[JumbleDuck]

Sounds a bit bizzare really, since LED colours are defined by the chemicals in them, which will not change.

True, and so a single LED can only produce monochromatic light. To produce white light they generally use a blue LED with a phosphor covering which absorbs the blue light and re-emits white. Arrays of red, green and blue LEDs have also been used but I think the phosphor route is more common now. Either way you get a spectrum which is significantly different from the spectrum of an incandescent filament. Less yellow/red, basically, so when you pass it through a green filter the output is biassed towards the blue end of the green

It would be very VERY interesting to see a picture of an old and new one side by side...

The light from my pulpit bicolour with warm white LED installed is definitely a blue-ier green than when it had an incandescent bulb. This worries some people a lot, but since it's still definitely green I can live with it. Free Mumsnet membership for anyone who replies "but it may invalidate your insurance".

 

[mariadz]

I seem to recall when I changed all of ours, I had to specify whether the LED was for port, starboard or stern light - they were not interchangeable. Silly question but you gave fitted the right one? Although i have no idea how the others would make a blue light.

 

[JohnGC]

True, and so a single LED can only produce monochromatic light. To produce white light they generally use a blue LED with a phosphor covering which absorbs the blue light and re-emits white. Arrays of red, green and blue LEDs have also been used but I think the phosphor route is more common now. Either way you get a spectrum which is significantly different from the spectrum of an incandescent filament. Less yellow/red, basically, so when you pass it through a green filter the output is biassed towards the blue end of the green

The light from my pulpit bicolour with warm white LED installed is definitely a blue-ier green than when it had an incandescent bulb. This worries some people a lot, but since it's still definitely green I can live with it. Free Mumsnet membership for anyone who replies "but it may invalidate your insurance".

The green defined in the col regs can be quite blue anyway.

 

[JumbleDuck]

The green defined in the col regs can be quite blue anyway.

Good point. I'd guess that my bicolour has moved from (01,06) to (01,04) on that diagram ... as it appears on my screen, of course.

 

[Boathook]

I used a sector'd LED which had green red and white LED's for the tri-light and through the coloured lens looks very good. If you have used just a warm white LED through a coloured lens then there is I believe a colour issue.

 

[Lon nan Gruagach]

True, and so a single LED can only produce monochromatic light. To produce white light they generally use a blue LED with a phosphor covering which absorbs the blue light and re-emits white. Arrays of red, green and blue LEDs have also been used but I think the phosphor route is more common now. Either way you get a spectrum which is significantly different from the spectrum of an incandescent filament. Less yellow/red, basically, so when you pass it through a green filter the output is biassed towards the blue end of the green

The light from my pulpit bicolour with warm white LED installed is definitely a blue-ier green than when it had an incandescent bulb. This worries some people a lot, but since it's still definitely green I can live with it. Free Mumsnet membership for anyone who replies "but it may invalidate your insurance".

The green defined in the col regs can be quite blue anyway.

Good point. I'd guess that my bicolour has moved from (01,06) to (01,04) on that diagram ... as it appears on my screen, of course.

Thinking on.....
LED green isnt ColRegs approved...
Mebby the device uses a white (made by R,G, and B LEDs) and then a green filter over that (or fades each RGB separately or mixes the appropriately (by power) as designed. The symptom of "turning blue" may just be the green element kicking the bucket.

 

[JohnGC]

Thinking on.....
LED green isnt ColRegs approved...
Mebby the device uses a white (made by R,G, and B LEDs) and then a green filter over that (or fades each RGB separately or mixes the appropriately (by power) as designed. The symptom of "turning blue" may just be the green element kicking the bucket.

Nor is any light source. What are defined are the colours.

Some years ago, when our local library had a subscription for BSI and I was free to look at all the standards I desired (on-line) in the reference library. I went on a hunt for the navigation light colour definitions. I don't remember the exact details, but it went something like this;

I began with a reference in the col regs to a British or Euro-Norm standard.
That led to a chain of other standards with each one deferring the colour definition to the next. I think there where about 4.
The final reference was back to the appendix in the col regs which defines the colours as polygons on the CIE curve (there is a table of XY co-ordinates for each colour).

The most interesting of these is for white; it can be quite yellow which I presume allows for oil lamps.

This was before blue was introduced for temporary wreak markers and I haven't checked since.

To meet a standard, a manufacture of lights must ensure the light (however created) falls within the region defined for a colour. How the colour is generated isn't/wasn't defined.

There are two caveats I remember;
1. There is a limit to the intensity of other colours a light may emit. For filament lamps this effectively defines the quality of the filters.
2. Light can not be electrically dimmed. No doubt because the colour shifts. (This is true of LEDs unless the dimming is done with PWM.)

I did that around 2003, no doubt the standards have been updated since. After all, no standards writer ever says, "We don't need any more standards, that it!".

 

[awol]

The green defined in the col regs can be quite blue anyway.

Actually just a tad greener than your diagram.
(ii) Green
x 0.028 0.009 0.300 0.203
y 0.385 0.723 0.511 0.356

 

[JohnGC]

Actually just a tad greener than your diagram.
(ii) Green
x 0.028 0.009 0.300 0.203
y 0.385 0.723 0.511 0.356

Yes, I was in a bit of a rush. I'll do a better job later! Thanks.

 

[theoldsalt]

Very old trick question - what is the colour of the glass in a starboard nav light.?
The correct answer is BLUE (ish). This is because oil lamps and electric bulbs tend to give off a yellowish light. Blue and yellow make green.
If the light source is changed to a very white led then the nav light will appear blue (ish).
I see this effect frequently in updated traffic lights.

 

[lpdsn]

Very old trick question - what is the colour of the glass in a starboard nav light.?

The correct answer is Green. I have one here from an 25 years old Aquasignal light I replaced. I admit it does look a bit bluish against a cool white LED (I have a mixture of cool and warm white LEDs in the kitchen) but is OK with warm. And it was fine with green LEDs when fitted on the boat.

And anyway, far better to have brighter lights with lower current draw. Far better to have the OOW on the bridge saying to the lookout "Do you think the lights on that WAFI have a slight bluish tint?" rather than "Where the F did that B with the faint lights come from?".

 

[JumbleDuck]

And anyway, far better to have brighter lights with lower current draw. Far better to have the OOW on the bridge saying to the lookout "Do you think the lights on that WAFI have a slight bluish tint?" rather than "Where the F did that B with the faint lights come from?".

Absolutely. As Ann Davison wrote - I paraphrase - I'd much rather the lookout on a large ship said "What the hell is THAT?" than that they didn't spot me.

 

[lw395]

White LED spectra are not continuous.
They are a collection of fairly sharp lines from the 'phosphurs' used to convert blue or UV emissions from the diode into something that the human eye perceives as white light.
Modern LED phosphors have many more lines than early ones. Some old white LEDs were quite awful, but even now a lot of things can look different under a halogen lamp of the same colour temp.
Coloured filters are not always continuous either so it's possible for odd things to happen.
The response of the human eye is complicated too.
Then you have to allow for some other human not perceiving the light the way you do.

I'd be a little concerned about a 'green' that looked too blue, as their are 'whites' out there looking fairly blue.

 

[GHA]

A little test this afternoon,

Switching between some white and green cree LEDs

Making your own LED lights isn't that tricky and costs little.

 

[PetiteFleur]

Well. I understood you should use warm white LED's in the Bi-colour bow light which is what I fitted. I looks ok to me and certainly looks brighter than the incandescent lamp. The stern has a cool white which is very bright, I've still to do the tricolour which will be done this winter when the mast is down, replaced with a dedicated red, green, white LED lamp. The steaming light is still incandescent as not found an LED which will fit, anyway the engine is running so not really a problem.

 

[rptb1]

Well. I understood you should use warm white LED's in the Bi-colour bow light which is what I fitted. I looks ok to me and certainly looks brighter than the incandescent lamp. The stern has a cool white which is very bright, I've still to do the tricolour which will be done this winter when the mast is down, replaced with a dedicated red, green, white LED lamp. The steaming light is still incandescent as not found an LED which will fit, anyway the engine is running so not really a problem.

I did something similar on my boat but found a way to make a warm LED fit into an incompatible incandescent fitting. You can take a look here: https://tammynorie.wordpress.com/2015/09/08/bow-light-led-hack/

I question the need for a tricolour when you already have efficient deck-level lights.

 

[Oldhairy]

I question the need for a tricolour when you already have efficient deck-level lights.

Depends on at what distance you wish to be seen.