Night light for chart work

Crazy-Diamond

Crazy-Diamond

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Hello all,

In planning for some night sailing over the coming months, I fitted a short strip of red LED lights over the chart table, simply assuming that this was the correct procedure. I tested them over the last weekend, and not only did I find them too bright (I have about 15 in a ribbon) but the red light made my Imray charts very hard to see. I reverted to a very dim white light, which may have damaged my night vision, but at least I was able to see and plot on the chart.

What is the correct accepted method for this? White or Red?

Giles
 
Red is the colour that has been used traditionally, but it does make red features on the chart hard to see, as does the dimness of the bulb, as used in the flexible map-reading lamp fitted to most boats built in the last forty years or so. In fact, the brightness of your string of LEDs may be more than would be considered necessary.
I have acquired a headlamp which has both red and green LEDs, which I hope to experiment with soon, to see if the green light is more suitable.
 
I am tempted to try using a very dim white bulb. I think I'd rather be fully informed about the navigation than have the best night vision. If the bulb is dim enough there may be a good balance....
 
Whatever you use needs to be VERY dim to avoid defeating your night vision. An LED strip will be WAY too bright - a single low power LED bulb (think instrument panel bulbs) would be more like! Once your eyes have adapted to darkness, they are surprisingly efficient in dim light; even the light from my chart-plotter at it's lowest setting and in night time colours seems very bright. However, night vision is effectively monochrome, so your chart needs to be readable without colour information. Admiralty charts (which adhere to IHO international standards) are certainly designed to be usable in low light conditions; I would have hoped that other suppliers would have looked at that aspect when designing their cartography.

If you can distinguish colour, the light is too bright and will degrade your night vision once your eyes are fully dark adapted. That's why the colour characterisitics of lights are given in the abbreviations as well as by the chart symbol - the colour of the chart symbol may not be visible.
 
I have used a truckers red light for years. The important bit is it has two bulbs in it wired in series , to get a suitably dim light for the truly dark night. Needless to say they have lasted for years, and the current is very very low.
 
I have both.

Under the side deck above my chart table is a strip of red LEDs and a strip of white LEDs. They're fed by a dimmer circuit and a changeover switch, so I can select red or white and the preferred brightness. At night I will set these ones to a very dim red, to make the general area of the chart table visible.

Then, under a wooden lip just above the surface of the table, which hides the clamps that hold the chart in place over the Yeoman, there is a strip of white LEDs angled to spread light across the face of the chart but not shed any upwards. These are on a separate dimmer, and they put just enough white light onto the chart itself so as not to hide red and orange features.

Finally, the chart table light panel has a master on-off switch that is bigger than all the others and placed against the woodwork so that your hand is naturally guided onto it in the dark. This lets you set the dimmer knobs and red/white switch as required, and then easily flick the whole lot off as you stand up and on as you sit down.

Some people would probably say I overengineered it ;)

Pete
 
We have a dim diffused red LED above the table. I find it relatively easy to read anything that isn’t magenta but some of older crew members sometimes struggle. I tend to note down anything important that is in magenta on my passage plan notes.

I do have a head torch that has a red light if I want a little brighter but I use it sparingly and make sure it’s off before heading back to the cockpit. Biggest risk to night vision on one of the board I regularly sail is the light in the heads. The switch is just where you might lean if on starboard tack and there’s a window out to the cockpit. :rolleyes:
 
prv said:
. Some people would probably say I overengineered it ;).
Pete
Click to expand...

Yep, I think you have.

Most of the time below decks will be doing multiple things - kettle on, check chart then make tea/coffee etc. Perhaps heads visit also. Could spend all day fiddling with all your various lights witches and dimmers.

I tend to keep a small £1.99 LED torch in my pocket at night. And either use this, or more likely simply use the glow from my phone home screen. Both can be moved around to cover all of the tasks without touching any light switches. (Can’t actually recall if the boat has a chart table light, suspect it has but that may have been a previous boat. Didn’t work on that boat and never bothered to fix it!)

And I was advised that a head torch is a no no except on singlehanded boats. Other person says something and you immediately turn round and blind them with your eBay torch.
 
dunedin said:
I tend to keep a small £1.99 LED torch in my pocket at night. And either use this, or more likely simply use the glow from my phone home screen. Both can be moved around to cover all of the tasks without touching any light switches. (Can’t actually recall if the boat has a chart table light, suspect it has but that may have been a previous boat. Didn’t work on that boat and never bothered to fix it!)
Click to expand...

I Agree Convenient except for the silly part where they go on to the flash on every third press of the button Grrrr
I just cannot see the point of the red light& very often I just turn the cabin light that is not in the direct line of sight of the helmsman on.
I really do not think that they affect night vision as much as people claim. But then I can see b..ger all any way:ambivalence:
 
I use some very dim green LEDs over the chart table as orienting light and then a white 'flash light bulb' LED on a flexible arm for a concentrated spot to see finer detail (and get the colours right).
The white spot looks very bright in this photo, but it is just how the camera sees it.
nightchart2.jpg
 
If you want to preserve your best night vision, dull red illumination is the best. If you want to see detail, colour, or just process information rapidly, white light is better.

When sailing there are times when one or the other modes predominant. Sometimes night vision is critical, but during these times you may still want some reference to a chart and dull red is hopefully enough. At other times detailed information from a chart or other source such as radar, AIS etc may be more important than maintaining the best dark adaptation. In this case sacrificing some night vision to obtain the best information from charts and other sources may be sensible, so dull white light is better.

So the best solution is a combination of dull red and dull white, matching illumination to the requirements. Surprisingly few yachts have suitable illumination.
 
prv said:
I have both.

Under the side deck above my chart table is a strip of red LEDs and a strip of white LEDs. They're fed by a dimmer circuit and a changeover switch, so I can select red or white and the preferred brightness. At night I will set these ones to a very dim red, to make the general area of the chart table visible.

Then, under a wooden lip just above the surface of the table, which hides the clamps that hold the chart in place over the Yeoman, there is a strip of white LEDs angled to spread light across the face of the chart but not shed any upwards. These are on a separate dimmer, and they put just enough white light onto the chart itself so as not to hide red and orange features.

Finally, the chart table light panel has a master on-off switch that is bigger than all the others and placed against the woodwork so that your hand is naturally guided onto it in the dark. This lets you set the dimmer knobs and red/white switch as required, and then easily flick the whole lot off as you stand up and on as you sit down.

Some people would probably say I overengineered it ;)

Pete
Click to expand...

I think your system sounds wonderful, even if some naysayers would describe it as over-engineered... I don't have a fixed chart table, but a chart case that can be moved around somewhat.

I tend therefore to use either one of the relatively dim and warm white 12V halogen reading lamps in the saloon, or, more often, the head torch I keep on my head/around my neck at night. - edit: on the red light mode, switching to white or using the halogen bulb only if I can't read something and need to see it urgently, which doesn't happen that often to date.

I bought some £5 Amazon jobs a couple of years ago which are fantastic—bright enough on the white light setting, but they have a separate red light button, so one can turn the red light on without paging through the white light setting and blinding everybody. They can also be angled down to point at the deck/chart. I think these are important feature on crewed yachts, per other peoples' remarks on head torches in general...

Also, even when single-handed, you don't want to lose your night vision unnecessarily!

William
 
I struggle with low red light so find low white ideal, I did read a research paper last year that indicated that retaining night vision is more about the intensity rather than colour, red is historically just easier to have at a low level but with white LED this is not an issue anymore.
 
Intensity is certainly an issue, I looked through the binoculars at a passing channel marker just as the light illuminated, which ruined the night vision!
 
Daverw said:
I struggle with low red light so find low white ideal, I did read a research paper last year that indicated that retaining night vision is more about the intensity rather than colour, red is historically just easier to have at a low level but with white LED this is not an issue anymore.
Click to expand...

+1. and also did read an article several months ago that said exactly that. Blowed if i can find it now though. Dim white is better for me and it definitely makes it easier to read the chart with my poor eyesight.
 
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