Night vision

[Daydream believer]

Am i the only one?
All advice is to use red lights for reading charts or for low level instruments at night
I have tried this & cannot see a thing. I always end up turning on the cabin lights when i go below to read charts etc or i use a small LED torch (& magnifying glass if my glasses are steamed up)
I do not notice much difference when i go back on deck unless i have looked straight at the cabin lights or a torch
If a crew goes below we always ask them to use the cabin light which cannot be directly seen by the helm
Re instruments i always have on max illumination.
Never really notice much difference to night vision - or is it because my eyesight is fading anyway?
The only real hassle is coming into Bradwell creek at night- i say something to the crew on the bow with the torch & he always ( never fails) turns round to reply & gives me a burst of 1 million candellas . That does b..r up the vision

 

[jwilson]

I have never found red light to be any help - prefer a dim white light at chart table plus an illuminated magnifier if required for detail.

At the helm though have often turned off instrument lights apart from the compass, prefer to sail he boat rather than a row of dials.

 

[tillergirl]

I find that the light polution from my nav lights is pretty strong which actually means that like you using the lights below has little affect. No doubt the light pollution does reduce my night vision but I found we were seeing things beyond the boat quite well.

For some reason Bradwell Creek in the dark does seem especially 'dark'!

 

[rivonia]

Yup we are the same. We have fitted those led lights that are made by Cheap chinese labour. So if we have to go below just a press on the light and a single bulb lights up, two press's and two lights come on, however third press and its like blackpool illuminations. The red light is useless, does not make for easy chart plotting.

 

[Pye_End]

I use as lower level of light possible at night for whatever needs doing. I have low level red LED for doing things like filling the kettle, but for chartwork using red light makes some of the colours disappear (eg TSS boundaries), so tend to use as lower level of white as possible (eg finger covering end of a torch). My instruments on the lowest setting (mostly) are fine, and often find full light intrusive on one that cannot be turned down.

Do you find you are leaving the instruments on max out of habit or because it is the minimum you need to read to see them? Perhaps turning everything down for half an hour, and trying to avoid turning on bright lights will give you an idea as to whether it is down to aging eyes or not. What do your crew say about light levels, and do they have better eyes?

 

[pampas]

Nearly all the ships I have worked/sailed on have orange filters, Red I find changes the colours of the chart and as observed not very practical, A light blue also is useful and whatever one uses it should have a dimmer fitted.

 

[sarabande]

UKHO has taken great care to ensure that, when red light is erroneously used to look at charts by night, the colours do not become confused.


Research has amply demonstrated that the best light for night work is low 'white' light.

http://stlplaces.com/night_vision_red_myth/

 

[noelex]

It is very hard to read a chart properly with red light.
It want to read it with white light you need to accept that night vision will be reduced and it will take 15-20 mins before full dark adaption is reached.
If you are not noticing any difference when you go on deck after reading the chart its likely that your level of dark adaptation on deck is poor.
This fits in with having having your instruments on full bright.

When sailing at night is not always best to aim for full night vision.
Often checking the chart seeing the radar/ chartplotter /AIS etc takes precedence and to use these tools easily and well, you need to accept some reduction in night vision.

However there are times when full night vision is beneficial. It is important to relise these situations and switch gears when required.
With two people one up at the bow (without a torch its amazing what you can see with full dark adaptation) and someone at the helm using the instruments is often the best solution.
There are times when a torch at the bow is best, but It is important to realise with this bright light source it will take 30mins to regain your full dark adaption so don't turn it on without careful consideration.

The eyes dark adaptation is retinal, so blocking off on eye and retaining night vision in one eye is sometimes a good compromise.

 

[KellysEye]

We had a small white light and the charts were easily visible as were the ship lights when I went back on deck. It didn't affect night vision at all.

 

[nigelmercier]

It is clearly impossible to read a paper chart with red light, but it is good for finding things.

 

[markhomer]

talking of night vision

my nephew appeared with these other day http://www.amazon.co.uk/Spy-Net-Nig...97751&sr=8-4&keywords=night+vision+binoculars

im ashamed to say we did exactly as one of the reviewers did , ie straight into cupboard under stairs , and yup they work amazingly well !!!!!, see only good for 50 foot , but for those dodging up mooring littered rivers or approaches 50 foot from bow in pitch black must be usefull

 

[nigelmercier]

talking of night vision ...

My son is alleged to have a US military specification night-vision scope, which is illegal to export from the US; the loop-hole is to export it as spare parts! Cost about two grand, but awesome. If you go for a domestic model such as a Yukon, don't get the X1 magnification; the X2 or X3 work a lot better.

I've got one of these on the boat, quite handy: http://www.amazon.co.uk/exec/obidos/ASIN/B0002HBOPQ/dolcetto-21

 

[Sailingsaves]

UKHO has taken great care to ensure that, when red light is erroneously used to look at charts by night, the colours do not become confused.


Research has amply demonstrated that the best light for night work is low 'white' light.

http://stlplaces.com/night_vision_red_myth/

Agree. Haven't looked at the link but it was proved to me a long time ago (scientifically) that dim white is better than red for chart use = sorry can't remember any data links.

 

[Sailingsaves]

My son is alleged to have a US military specification night-vision scope, which is illegal to export from the US; the loop-hole is to export it as spare parts! Cost about two grand, but awesome. If you go for a domestic model such as a Yukon, don't get the X1 magnification; the X2 or X3 work a lot better.

I've got one of these on the boat, quite handy: http://www.amazon.co.uk/exec/obidos/ASIN/B0002HBOPQ/dolcetto-21

I worked for the Home Office Scientific Branch (made kit for police) in my youth and even then they had some mind blowing night vision and thermal imaging protoypes = I would have loved to have been allowed to have one. Sadly, whilst the facilities were top notch and money wasted on chairs and loos - best toilets I have ever seen = marble tops = shiny taps = the pay was pathetic and I moved on.

 

[nigelmercier]

it was proved to me a long time ago (scientifically) that dim white is better than red for chart use...

No need to be terribly scientific, printed colours work by absorbing all the colours except the one they reflect. If that colour is not present in the illumination, it cannot be reflected, so will appear black.

 

[Sailingsaves]

No need to be terribly scientific, printed colours work by absorbing all the colours except the one they reflect. If that colour is not present in the illumination, it cannot be reflected, so will appear black.

Quite, but why has the myth been around for so long? Too many submarine films or something?

 

[Sailingsaves]

Should have said, the scientific research bit stated that red was not needed to aid night vision and that dim white was equal to red light in not affecting night vision.

Obviously as you point out that is quite true for charts.

I don't know if what I wrote in sentence one is true for night vision = it was just what I was told = biology is not my kettle = lucky if I can tell a finger from a toe.

 

[noelex]

We had a small white light and the charts were easily visible as were the ship lights when I went back on deck. It didn't affect night vision at all.

If you are using a white light to read a chart your night vision is effected.
I am afraid this is an unavoidable aspect of the eyes physiology.
White light even at at a low intensity that is only just bright enough to see detail, bleaches out most of your rod function.
There is no way around this (in the eye used)

That does not leave you with no dark adaption, but its important to understand as soon as you use a white light to read a chart full dark adaption is going to take 15 mins.

Often full dark adaption is not needed. On other occasions the reduction of night vision is outweighed by allowing the chart etc to be seen easily and in detail.

At least try to set the boat up so that full dark adaption can be achieved when required. When contemplating something that will reduce your night vision consider if benefits outweigh the inevitable loss of some night vision.

 

[Sailingsaves]

If you are using a white light to read a chart your night vision is effected.
I am afraid this is an unavoidable aspect of the eyes physiology.
White light even at at a low intensity that is only just bright enough to see detail, bleaches out most of your rod function.
There is no way around this (in the eye used)

That does not leave you with no dark adaption, but its important to understand as soon as you use a white light to read a chart full dark adaption is going to take 15 mins.

Often full dark adaption is not needed. On other occasions the reduction of night vision is outweighed by allowing the chart etc to be seen easily and in detail.

At least try to set the boat up so that full dark adaption can be achieved when required. When contemplating something that will reduce your night vision consider if benefits outweigh the inevitable loss of some night vision.

There you go, told you I know nothing of biology and wherever I got that "scientific" research that dim white did not affect night vision was wrong according to you - still stands for charts though of course - white dim is best for chart use as opposed to red even if the UKHO make super dooper charts.

Adding this bit: Agree again, boats should have red and white because I find my red head torch function does not wake others up whereas the white does. As Nigel said, red is fine for looking for odds and ends.

I also love even if don't understand the cones and rods biology and how at night peripheral vision is better than straight ahead and hence why we are taught to use the figure of eight motion when looking around at night.

 

[nigelmercier]

Quite, but why has the myth been around for so long? Too many submarine films or something?

But it isn't a myth that red light is less disruptive to your dark adaption, it's just no good for reading a chart.

http://en.wikipedia.org/wiki/Purkinje_effect#Use_of_red_lights