Looking for commercial endorsements and/or the more advanced amateur tickets (Coastal to Ocean).
I have a red & green vision deficiency, while I am not completely colour blind. And while sometimes it takes me a while to recognise the colour of a distant buoy or a light, I do fare quite well while navigating. Due to many factors, sometimes seeing it first despite everything, and sometimes just knowing what should be where, I often know what's going on before better-sighted mates do.
Does anyone have experience if RYA/MCA are willing to issue restricted tickets for the 'colour blind' like me, or perhaps even equate practical abilities over the medical exam?
This is embarrassing, never been in trouble (quite the opposite) in practice, .. until reading up what they want.
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Thread: Colour blind & RYA/MCA
20-10-09, 19:55 #1New User
- Join Date
- Oct 2009
Colour blind & RYA/MCA
21-10-09, 13:07 #2Registered User
Location : Devon
- Join Date
- Jan 2007
There are no colour vision testing requirements for the RYA exams, but if you fail to identify nav lights at night I suppose you would fail.
The formal test is required as part of the medical assessment for the commercial endorsement.Go to the MCA web site and search on "colour vision". You will find various documents. The issue for you is fitness for lookout duties. If you can pass the Holmes Wright B lantern test you would be "fit" and therefore should be able to meet the standard required for a commercial endorsement. I don't know the mechanism for getting the test and the waiver from the MCA, but if you read any relevant documents you should be able to find out.
Why be embarrassed? About 8% of white, male, Europeans and Americans have a significant red/green deficit.
Last edited by andygc; 21-10-09 at 13:11.
21-10-09, 13:22 #3
When I took the old Board of Trade yachtmaster the exam involved a sight test using coloured lamps in a dark room. Some colour blind people managed to get through because when they used oil lamps the colours showed up as different intensities. I recall one experienced mariner who was completely stuffed when they changed to electric lights.
These days there is no sight test for exams up to Yachtmaster though there is a colour blindness test in the medical required for the commercial endorsement.
I presume you know about the red & green colour filters you can use to distinguish red and green lights. I can't imagine an examiner would fail you if you used a set of these and were able to get the correct readings with them.
For the benefit of anyone who is red/green colour blind and doesn't know about these, you get a pair of red and green filters. When you look at a red light through a green filter you can't see it, likewise a green light can't be seen through a red fillter. You use them by moving the filter back and forth across the light in question. If the light is white or the same colour it shows all the time. When the light is the opposite colour it will wink out as the filter goes in front of it.
A friend with this condition described red and green as 'a dirty shade of yellow'. I imagine it is possible to distinguish between white and yellow lights.One hull good, two hulls better.
21-10-09, 13:37 #4
In most cases of red/green defficiency, the red/green receptors are tightly concentrated in the centre of the retina rather than being more widely distributed as is the norm. As you may know, many red/green 'defficients' can often discern colour quite accurately by staring at the object directly.
There are products such as http://www.color-view.com/ which will enhance red/green differentiation. In fact all you need is a single pink-tinted contact (or spectacle) lens.Thick as two short planks
21-10-09, 14:15 #5
I have a friend who had the same issue.
He had a yachtmaster ticket, so I don't think that it restricts you from getting the ticket. But when he wanted to get commercially endorsed he couldn't.
I've never asked him the details, so I don't know the exact reason/test that stopped him, but I do know that he wanted to be commercial but couldn't on account of his eyesight.You never know, I might be right!
21-10-09, 14:46 #6Registered User
Location : Edinburgh, Scotland
- Join Date
- Apr 2007
I think if an examiner realised you had difficulty distinguishing red/green, during your YM practical exam, that might give them pause. There is probably guidance for examiners on this matter.
I do know that when I had a medical for commercial endorsement the doctor conducting the examination was delighted to be able to test my colour vision and field (peripheral) vision, because those were about the only actual medical tests, all the rest was just questions about whether I had ever had a stroke or whatever.Ken McCulloch
Rival 38 'Cherry Ripe'
21-10-09, 16:35 #7Registered User
- Join Date
- Jul 2005
21-10-09, 19:38 #8Registered User
Location : Devon
- Join Date
- Jan 2007
It's really quite simple, you either have adequate red/green discrimination to distinguish between red, green and white lights at night, or you don't. For maritime purposes the Ishihara plates are a screening test - if you can read them you are for practical purposes red/green normal. If you can't read them you need a specific occupational test, which is the Holmes Wright lantern. That uses red and green filters that match the internationally standardised colours for navigation lights. If you can't pass the Holmes Wright lantern test you are unsafe to act as a lookout at night and you will not meet the standard for a commercial endorsement or any other professional watch-keeping certificate.
elton's theory is marvellous, but as noelex suggests, is nonsense. The cones (colour sensitive cells) are wholly concentrated in the centre of the retina. Red/green defects (of which there are two different types) arise (in simple terms) because of either a substantial or complete lack of red or green sensitive cones. Vision in the periphery is mediated by rods which provide monochrome vision.
The colour filters mentioned by snowleopard might work for some people some of the time, but are not a reliable means of discriminating between navigation lights. These filters work by relying on the substantial overlap in the spectral sensitivity of red and green cones. There is overlap with blue, but much less so. Even the best colour filters have some transmission loss. These will not stay in good optical condition for long.
The unreliability arises because the filter will reduce the brightness of the light which is being detected by a cone which is not particularly sensitive to that wavelength. So, for somebody who is red cone deficient, a green light through a green filter is dimmed by the filter, but detected by the green cone. A red light through a red filter is dimmed by the filter, but has to be detected by the overlap sensitivity of a green cone. It needs to be bright to be seen. The approaching red light on the starboard bow will be seen initially as a 'don't know' which disappears when seen through both red and green filters, remaining a 'don't know'. It eventually becomes a dim light seen through a red filter, shortly before the crash alteration of course to give way to a crossing vessel.
Of course, you also have to remember which is the red filter and which the green, because if you are colour deficient you probably can't tell by looking at them, especially in the dark. Strikes me that they are a great idea.
Last edited by andygc; 21-10-09 at 19:42.
22-10-09, 09:27 #9
For MCA issued tickets you will need to pass the MCA lantern test - a series of red, green, white and yellow lights set at brightness of 6 miles (I think that was what it was when I did mine?).
**This used to have be taken without any reading or eyesight aids.**
Having a letter from your optician to state you had god vision and were not colour blind wasn't accepted, you had to pass their lantern test and it was only valid for 6 months from date of issue (but you didn't have to take it again until you upgraded your ticket. If you fail you used to be able to get referred to an MCA approved optician - at your own cost who could retest you and issue a lantern test certificate.
So get your eyes checked first before you spend.
My advice would be to contact the MCA first about your eyesight concerns and ask them how you should proceed.Drinking rum and playing music with my friends.
22-10-09, 18:49 #10Registered User
Location : South Wales
- Join Date
- Mar 2005
I am red green colour blind and have found the red/green lenses (spelling) to be a great help. My vision other than colur blindness is excellent and don't need to wear wet,steamed up glasses as a number of friends are forced to do on bad nights.I just look upon the lenses as some one with poor eyesight would look upon their spectacles.
I also realise that white steaming lights are normally brighter than red and green lights and play a major part in identifying the course of a craft.
I am also surprised how many red/green colour blind sailors are around.