Lights for Communication

[ucfdiver]

Re the signals and a tale about regional differences. Many of "us" in the PNW use a "flicking motion" of our lights to indicate direction of travel. When friends from SoCal came up, we just did that -- and they complained (or at least one did!) that the signal was very rude, not to mention disconcerting.

Other than the "big 3" I've realized it really does require some topside discussion as to what signals one might be using.

There's video of JJ/Casey/GI3 demo'ing that on the DIR2004 dvds for those that want a better idea of how it works.

 

[MXGratefulDiver]

Hmmm ... I thought the basic HID Salvo/Halcyon can lights that most cavers and techies use had a 6-degree beam.

In effect, the light has to be focused enough to produce a bright spot that can be "directed" so as to make a recognizable signal.

As to communication ... the most useful communication with any light is the "passive" one that lets your buddy know you are nearby without having to look ... in effect, placing your light in a place where it's visible to them without making them have to actively look for you.

Active signals I use frequently ...

"flick" for direction of travel
"OK" .. a single circle in a clockwise direction ... as with the hand signal, it requires a response
"attention" ... slow back and forth ... a request to look in my direction ... this signal is usually followed by additional communication
"emergency" ... a rapid back and forth ... a command to swim to me and be prepared to assist as indicated
"look in here" ... multiple slow circles ... typically used after the "attention" signal to indicate that there's something of interest inside the encircled area (that I don't want to scare off by shining my light on it)

... Bob (Grateful Diver)

 

[Gombessa]

Hmmm ... I thought the basic HID Salvo/Halcyon can lights that most cavers and techies use had a 6-degree beam.

Bob, I think you're right. Salvo and Halcyon HIDs all have a 6 degree spot.

I believe what TS&M meant is that the LEDs tend to have a more uniform spill across that 6 degree beam, with no hotspot. That hotspot is what provides the high contrast and greater "throw" that allows an HID to penetrate murky water and catch attention.

 

[ae3753]

Earlier this year, I converted my DiveRite lighthead from the MR11 (4 deg. fixed*) to LED (6 deg. fixed).

The combination of HID to LED and 4 deg. to 6 deg, does make the light less desirable to me in caves and in open water. The lumen output supposedly doubled from 500 lumens to 1000 lumens, but I'm not seeing it.

With the upgrade, the light loses its hotspot, is more diffused, and signaling is not as effective. I need to be closer and my light signals need to be more assertive when diving with the LED head.

However, that being said, I can still communicate and my buddies haven't said anything to me about not getting information across or not seeing my light. And yes, they would definitely tell me.

Interestingly enough, I use the LED in open water and the HID head in caves. I have bad luck with HID bulbs, so I minimize the use to only when I really need it.

Here's a comparison between the MR11 to the LED 700 (700 lumens, not 1000 lumens).


* Random side note: The MR11 used to be classified as 6 degree and only recently started calling it 4 degree. My MR11s with SunSpot reflector were sold as 6 degree fixed. But today, it's marked as 4 degrees.

 

[Gombessa]

To those viewing Don's video, I'll point out that the LED probably looks a lot better in the clip than it does in person because the lights overexpose the image (both beams are bright enough to register as 100% white on the CCD). If you could reduce the exposure, what you would likely see is that the LED would fade to a uniform illumination of the subject, while the HID would remain an intensely overexposed hotspot.

Don - I couldn't tell what you were using on our last couple of OW dives, but in the bright, clear conditions we've had, I don't recall ever having a problem seeing your light or your signals. Maybe good technique has much to do with that, but whatever it is, it works!

 

[ae3753]

To those viewing Don's video, I'll point out that the LED probably looks a lot better in the clip than it does in person because the lights overexpose the image (both beams are bright enough to register as 100% white on the CCD). If you could reduce the exposure, what you would likely see is that the LED would fade to a uniform illumination of the subject, while the HID would remain an intensely overexposed hotspot.

Kenn makes a great point. The LED does look better in the clip than in person, and this was in a cavern with 300' viz. This is pretty much optimal diving conditions - no particles in the water, etc.

Also, LED diffuses much sooner. The distance of the video was <10', but in real life signaling your buddy may be a distance of 20' (you're signaling in front of your buddy to get attention).

Don - I couldn't tell what you were using on our last couple of OW dives, but in the bright, clear conditions we've had, I don't recall ever having a problem seeing your light or your signals. Maybe good technique has much to do with that, but whatever it is, it works!

I'd say it was a combination of good technique and great attention by teammates.

But I was also using a different light on our last dive together - a Salvo 12w LED. That's a pretty nice LED light.

 

[Thalassamania]

Here is a description (from an old post of mine) of a light signaling episode:

I turned to my left through about three-quarters of a rotation. I could see one of my three comrades coming up out of the herring mass, perhaps twenty feet away. She ascended about ten feet and pitched back to horizontal, leveling out and smoothly neutralizing her buoyancy. A circular shaped motion of her light indicated she was fine, had seen me and inquired as to my status with that unique economy of the underwater “OK.” I brought my seemingly detached left hand up out of the darkness and responded with a circle of my light.​

 

[gcbryan]

Hmmm ... I thought the basic HID Salvo/Halcyon can lights that most cavers and techies use had a 6-degree beam.

In effect, the light has to be focused enough to produce a bright spot that can be "directed" so as to make a recognizable signal.

As to communication ... the most useful communication with any light is the "passive" one that lets your buddy know you are nearby without having to look ... in effect, placing your light in a place where it's visible to them without making them have to actively look for you.

Active signals I use frequently ...

"flick" for direction of travel
"OK" .. a single circle in a clockwise direction ... as with the hand signal, it requires a response
"attention" ... slow back and forth ... a request to look in my direction ... this signal is usually followed by additional communication
"emergency" ... a rapid back and forth ... a command to swim to me and be prepared to assist as indicated
"look in here" ... multiple slow circles ... typically used after the "attention" signal to indicate that there's something of interest inside the encircled area (that I don't want to scare off by shining my light on it)

... Bob (Grateful Diver)

This was actually the basis for my question. I have a 10 w HID Light Cannon with a 6 degree spot. I was trying to envision the circumstances where that was not enough to communicate so I figured maybe the poster referred to had a focuses light that went to a tighter spot.

I also figured that maybe there were more signals than I had previously thought. I guess not.

 

[BabyDuck]

oh, there are huge amounts, they're just unofficial. mo2vation & hbdivegirl have *reams*! i think there's a post about them somewhere - if not here, then on dive matrix...