# Surefire M6R as a dive light?



## cryhavok (Sep 14, 2008)

I was wondering what everyone of a Surefire M6R being used as a dive light? Will this work? Am I better off getting one of those huge ugly plastic dive lights 

:thanks:


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## LukeA (Sep 14, 2008)

You will have big problems with water and the switch.


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## Illum (Sep 14, 2008)

it is interesting to notice that both the bezel and tailcap threads have two grooves for not one but two O-rings to be installed per light.:kiss:
the Tailcap, when fitted with two o-rings should permit the tailcap to screw on or off without leakage.

It should be waterproof to at least a couple meters as stated on the surefire manuals but no guarantees afterwards.:candle:


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## leukos (Sep 14, 2008)

I believe SF rates the M6 for 33 feet, but that would be without rotating the tailcap underwater. Why not get a dedicated dive light? Barbolight makes some very nice LED dive lights if you are looking for better craftmanship.


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## cryhavok (Sep 15, 2008)

Thanks for the replies, guys. 

I don't own a M6 yet, so I was wondering if I could get some extra duty out of it when I do buy one. I suppose it couldn't be outfitted with a clicky? 

Is there anywhere I can look to find out the latest Barbolight creations for diving? Their site stays it is under construction. Google search brings up models using Luxeon III leds. I'm not sure of the Barbolight terminology.


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## Monocrom (Sep 15, 2008)

You really are better off with a dedicated Dive light. I love my M6. But it wasn't made to be submerged for any length of time.


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## mdocod (Sep 15, 2008)

I comfortably take my M6 into the rain and such, but would not consider this to be dive ready in any sense.

Aside from the water issue, dive lights are generally something you want to turn on and be able to leave on, providing light for a long period of time. An M6 can do this well with a lower output lamp, like say, an MN15, but that lamp is over-driven heavily like that, reducing reliability.

For Dive applications, LED and HID are probably much more appropriate.


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## leukos (Sep 15, 2008)

cryhavok said:


> Is there anywhere I can look to find out the latest Barbolight creations for diving?


 
Sorry, I didn't realize their website was under construction. I'm assuming they are planning on coming out with a full line of dive lights with CREE leds. Their current tactical line are still rated for 20 ATMs (660 feet), not sure how much depth rating you need for your application: http://www.barbolight.com/tactical/


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## js (Sep 15, 2008)

Don't use your M6 as a dive light! Bad idea, bad idea! Get a dedicated dive light that uses NiMH batteries, which perform very well at cold temperatures, unlike Li-ion or Li-Mn-O2 or alkaline, which lose a non trivial amount of performance at 0 C.


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## Outdoors Fanatic (Sep 16, 2008)

js said:


> Don't use your M6 as a dive light! Bad idea, bad idea! Get a dedicated dive light that uses NiMH batteries, which perform very well at cold temperatures, unlike Li-ion or Li-Mn-O2 or alkaline, which lose a non trivial amount of performance at 0 C.


Actually, LEDs are attrocious for diving. If color rendition is already bad in dry athmosphere, you have no idea how worse it is underwater with all those little sea water particules, sand and algae reflecting and backfiring the light everywhere. Most recreational dives are done in less than 30 minutes, so incans are still the best option (or HIDs if you arer serious about night diving). I use a Princeton Tec Shockwave and a UK SL-4 for backup, all xenon and all reliable as hell.


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## js (Sep 16, 2008)

Outdoors Fanatic,

I wasn't talking about incan vs. LED. Just about battery chemistry, regardless of the light source. CR123A primaries lose a lot more performance at 0 C than NiMH.

But in any case, I'm sure you are correct about the performance of LED's underwater! My objection to the M6 wasn't because it was an incan, but because the seals aren't rated for as deep as a "real" dive light, and because of the Li chemistry.


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## Outdoors Fanatic (Sep 16, 2008)

js said:


> Outdoors Fanatic,
> 
> I wasn't talking about incan vs. LED. Just about battery chemistry, regardless of the light source. CR123A primaries lose a lot more performance at 0 C than NiMH.
> 
> But in any case, I'm sure you are correct about the performance of LED's underwater! My objection to the M6 wasn't because it was an incan, but because the seals aren't rated for as deep as a "real" dive light, and because of the Li chemistry.


Hey Js, sorry man. I was trying to quote *Mdocod, *not you... my bad! The "Post Quick Reply" function is tricky.


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## Patriot (Sep 16, 2008)

There are several threads available to search regarding the water resistance of Surefire lights. Basically, Surefire only rates their lights as "weatherproof" but not submersible. That said, many would feel quite comfortable dunking their Surefire light in a bucket of water if it fell in the mud and some would even feel confident about snorkeling in two or three feet of water with an M Series light. It's just that it's not rated for submersion so it's not recommened. 

Many CPFers, including myself believe that Surefire should give their lights a water resistance rating since then the user would know for sure. They instead play it safe by the "weatherproof" statement which probably covers them well with regards to warranty liability. On the other hand I realize water ratings for a product range as extensive as theirs would require another team of people at great expense which probably isn't cost effective. Also, it's not like they have trouble selling product regardless of the lack of water rating. They seem to be a very smart and practical company and I have to give them credit for that.


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## Illum (Sep 16, 2008)

well, diving with a flashlight will put the light through a heck of alot of other variables than just that of a bucket of water

"weatherproof" is becoming a conservative term for moderate to good water resistance. Considering that surefire builds itself on providing the military special operations with worthwhile lights, I'm surprised surefire does not have a model or series dedicated for the frogmen division:shrug:


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## Patriot (Sep 16, 2008)

Illum_the_nation said:


> I'm surprised surefire does not have a model or series dedicated for the frogmen division:shrug:




I'm not certain but I think the Surefire 6PN may still offered as special order item. I've never personally seen one but apparently it's indistinguishable from the standard 6P other than the package with a sticker stating, "tested to 33m."


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## sed6 (Sep 16, 2008)

js said:


> Don't use your M6 as a dive light! Bad idea, bad idea! Get a dedicated dive light that uses NiMH batteries, which perform very well at cold temperatures, unlike Li-ion or Li-Mn-O2 or alkaline, which lose a non trivial amount of performance at 0 C.


 
Agreed that Lipo's/Li-ions don't like the cold, but where in the world did you get 0 c? Most recreational diving takes place in 77-82 F water, a perfect temp for Lipo's/Li-ions to deliver their maximum capacity. You'll find many high end dive lights rely on them for their great energy density.


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## Patriot (Sep 16, 2008)

I know that HID is also a popular lighting format for diving and most of the high end lights are li-ion. Maybe arctic conditions would cause some lost of performance but like you eluded to, that's an extreme condition.


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## Illum (Sep 17, 2008)

Patriot36 said:


> I'm not certain but I think the Surefire 6PN may still offered as special order item. I've never personally seen one but apparently it's indistinguishable from the standard 6P other than the package with a sticker stating, "tested to 33m."


 

well, I know of this model but only through the discussions here on the forum...often with Size15s, I've never seen a pic of this little 6P but from what I can see oberving the use of incandescents in murky freshwater I'd expect surefire to make a light with a bigger reflector for throw. Water eats lumens almost as hard as my van drinks gasoline, especially dirty water


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## js (Sep 17, 2008)

sed6 said:


> Agreed that Lipo's/Li-ions don't like the cold, but where in the world did you get 0 c? Most recreational diving takes place in 77-82 F water, a perfect temp for Lipo's/Li-ions to deliver their maximum capacity. You'll find many high end dive lights rely on them for their great energy density.



Good point!

0 C was just a convenient data point. I know most people don't dive in water that cold. I guess I was thinking about the usual temp around where I used to live in Maine: about 50 F if I remember correctly, which will definitely affect Li-Mn-O2. Heck, even room temperature water will do that. Check out McGizmo's thread: A Paradox to thermal relief. I think that was the name of it.

Point is that CR123A's like to run hot--like 90 F or better--for best performance, and suffer at 60 or 70 F.


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## steve6690 (Sep 17, 2008)

Interesting points...I'll let you know how my home-made Li-ion pack performs this winter on 1 hour dives in 4 degree C water...
I don't agree that led is a bad choice for diving though. Whilst HID lamps are better for signalling because they produce a much tighter beam, that's IMHO only because led lamps have to use several led's, and therefore multiple reflectors, to get the same brightness as, for example a 21 watt HID (around 1500 lumens). When we reach a point where one led can produce 1500 lumens or so and therefore be used singly in a lamp I think a single larger reflector would be able to produce a narrow enough beam to cut through the murk like an HID. Salvo are getting there, but I would argue their "21 watt led" lamp could have benefitted from a different reflector to give a tighter beam. Here's a useful comparison :

http://www.yorkshire-divers.com/forums/torches/77536-salvo-21w-led-vs-21w-hid-part-1-a.html


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## Patriot (Sep 20, 2008)

steve6690 said:


> Interesting points...I'll let you know how my home-made Li-ion pack performs this winter on 1 hour dives in 4 degree C water...
> I don't agree that led is a bad choice for diving though. Whilst HID lamps are better for signalling because they produce a much tighter beam, that's IMHO only because led lamps have to use several led's, and therefore multiple reflectors, to get the same brightness as, for example a 21 watt HID (around 1500 lumens). When we reach a point where one led can produce 1500 lumens or so and therefore be used singly in a lamp I think a single larger reflector would be able to produce a narrow enough beam to cut through the murk like an HID. Salvo are getting there, but I would argue their "21 watt led" lamp could have benefitted from a different reflector to give a tighter beam. Here's a useful comparison :
> 
> http://www.yorkshire-divers.com/forums/torches/77536-salvo-21w-led-vs-21w-hid-part-1-a.html






I picked up on the incan vs. LED vs. HID underwater discussion and the first thing that I noticed is that the talk as been very generalized and many variables are being ignored. 

I also agree with *steve *that LED's aren't necessarily going to be atrocious for diving. Some of the newer bins are amazingly natural in color and much closer to sunlight than 3300K incans. I think we have to remember how far LEDs have come and put to rest at least some of our dated reservations about them.

Likewise, all HID's are not "bluish" or 6000K+ color. The link above does demonstrate how some HID's can appear but just like LED's they vary in natural color (no glass tint) from 4000K all to over 6500K. The range from 4200K to 5000K is an exellent spread and reproduces sunlight like color as well or better than most LED's. 

With regards to 1500 lumen single LED's, yes they're getting close now since a hard driven, well cooled P7 is maintaining 900 lumens but that does not mean that the LED will be capable of the same throw, only the same overall output. It could still be many years before and LED is capable of reproducing the surface brightness of an HID arc, because right now they're still quite a ways off. The P7 is bright for sure, but it spreads that amount of output light arcoss a rather large area. I do think there will be another LED technology breakthrough soon but as we've witnessed it's not progressing as quickly as we might hope. When a Rebel sized die comes along that can produce 1500 lumens and can be sufficiently cooled then we've passed the surface brightness threshhold.


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## DM51 (Sep 22, 2008)

I have moved Barbarin's excellent post from here, and it is now post #1 in a new thread with the title Dive lights: LED vs. Incan. vs. HID. 

This thread may continue to discuss the unsuitability of the M6 as a dive light.


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## Barbarin (Sep 22, 2008)

Very good action, thank you.


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## Mercaptan (Sep 22, 2008)

js said:


> Good point!
> 
> 0 C was just a convenient data point. I know most people don't dive in water that cold. I guess I was thinking about the usual temp around where I used to live in Maine: about 50 F if I remember correctly, which will definitely affect Li-Mn-O2. Heck, even room temperature water will do that. Check out McGizmo's thread: A Paradox to thermal relief. I think that was the name of it.




When teaching open water in upstate New York, our dives would routinely be in 4 degree water. Advanced open water did night dives in 6 degree water. 

Needless to say, I gave up with alkalines a long time ago.

It's all well and great that most recreational dives occur in crystal clear, bath-water-esque Caribbean waters, unfortunately I was not afforded said luxury. Build a dive light for all rigors and locales.

I too am completely flabbergasted that Surefire doesn't have a dedicated dive light series. Oh, the 6PN doesn't count. Throwing on an additional o-ring won't cut it for me.

I would kill for a Surefire dive light.


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## Barbarin (Sep 22, 2008)

The way we design our lights to work with LiMno2 or Li-ION to avoid being affected by low temperatures is as easy and effective as to made battery tubes diameters 5-10 % larget than batteries diameter. That makes an insulating hot air chamber that keeps the battery warm. If the battery tube is too tight it will affect the runtime, for sure

It makes a huge difference.

Javier


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