Diving with “The Moderator”
I returned a couple of weeks ago from a diving holiday with my family, but it’s taken me that time to get around to doing a write-up about it.
Naturally, being a conscientious CPFer, I made sure I was fully tooled up with adequate underwater illumination equipment. Some of you may remember the modifications I made to a Navy dive light, which (until recently) I have been calling the “Yellow Monster”.
The full story of the light and the mod can be found in this thread, but its brief details are:
Originally made in 1993 for the British Royal Navy (looks like it could have been made in 1893, lol)
· Bright yellow
· 12 inches long
· 3 ins wide at bezel
· Solid ¼-inch thick cast aluminium body
· Heavy stainless steel tailcap
· A whopping 3 lbs 4 oz (1.5 kgs)
· 4.5V bulb (75 lumens)
· 3x alkaline D-cells
· Crappy reflector
Modded by me to take:
· Fivemega G4 bi-pin socket
· WA 1185 bulb (1,200 lumens)
· 3x AW protected ‘C’ Li-Ion cells
· Fivemega MOP reflector
· Other internal fittings, spacers etc
Before I went on holiday, I was thinking about labelling it with my name, but I realised this would be pretty pointless, as nobody else would be likely to have a light even remotely similar to this ancient dinosaur of the deep.
On an impulse, I instead reproduced the “DM51 / moderator” info as it appears at the top of my posts in CPF. I printed this on to a clear waterproof adhesive label and stuck it on the body of the light. It looked appropriate, and IMO really quite smart.
I fully expected some questions about this unusual label, but no-one, not even members of my family, seemed to realise what it signified. Perhaps they thought the light had come like that. I decided not to explain. Strange as it may seem, my family seem to be unaware that I visit this forum. They do not know what a moderator is, either. They know that I have an interest in flashlights, but that is all. So, much to my amusement, the light itself became known as “The Moderator”, and that is what I now call it.
Here is a pic of it disassembled (while the batteries are on charge). You can see what I mean by the label.
You can see I have fitted the light with 3 bolt-snaps – 2 to clip to D-rings on my harness when it is not in use, and a 3rd one which remains attached to prevent loss when it is in use, on the end of the safety cord (that is the original cord the light came with, BTW).
Here is another (not very good) pic, taken underwater, of the light attached to my harness.
It proved to be a fine dive-light. That big chunky twist switch is superbly easy to operate. The light is obviously as solid as a lump of granite. It is however about 2½ pounds negatively buoyant underwater, which is quite a lot.
And of course, with a WA 1185 bulb, it is BRIGHT!! At ~35 Watts and ~1,200 lumens, it demolishes most other dive-lights, and it is very gratifying to see the surprise on other divers’ faces when they see what looks like an obsolete relic blasting out so much light.
Here is a large eel (~5 feet long) which seemed pretty surprised too:
Many divers nowadays use LED dive-lights. When you just need to see where you are going at night or in caves, these are fine, and the long run-times / brightness / compact size make LED lights very useful indeed. However, they fall down badly in underwater color rendition – the weakness of the red component of the spectrum is even more pronounced due to its absorption by water.
Red will not penetrate more than 5m (15 ft) of water, so at even quite modest depths, recreational divers will never see any red colors unless they carry a light. Orange disappears at 15m, yellow at 30m, green at 60m and finally blue at 80m. Below that, it is pretty much black.
A powerful incan will bring back the missing colors in a startling way, especially the reds and oranges that are not otherwise seen even at normal recreational dive depths, and the Moderator certainly proved its worth. The pic of the eel above was taken during daytime, BTW, not night-time.
After the first dive, I was very pleased. I had run the light for nearly 40 minutes without noticing any problems, and it had more than lived up to my hopes for it.
However, there was to be an intriguing and totally unexpected problem with this light, which for a while had me totally baffled. It proved a fascinating problem to deal with – something very unusual, which has probably never been experienced before by anyone, with any light.
I will continue the story in a later post in this thread…