Light doubling

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roakey

Old, not bold diver
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Or “Why I think night diving is easier than daylight OW diving” :)

Light doubling (any other names for it?) is taught in the GUE Cave I course. It’s nothing new, but if you and your buddy become more aware of it and actually use it, it’s a powerful tool.

Light doubling is actually two things, first, when both of you illuminate one area you get to see it better, that’s obvious. But more importantly, if your buddy makes sure that his light crosses your field of view quite often, it allows the diver in front to keep track of rear diver without having to ever turn around. I usually cave in a team of three divers. If I’m the #1 diver, I’m always making sure that I’m seeing two other beams of lights playing on the walls in front and beside me besides my own. Divers 2 and 3 make sure that their lights shine forward at regular intervals so I can see them. The #2 diver always makes sure that he sees the beam from #3 at regular intervals (as well as looking forward at me). #3 just has to keep the first two divers in sight. On exit, the roles are reversed. This way it's easy for any one diver to keep track of the other two for redundancy.

We’ve done some long penetrations (long for my level) without the front diver ever having to turn around!

Upping your awareness of the diver’s light beams also helps in emergency situations where a diver starts shaking his light. If you’re not used to looking for the other’s beams, you might be slow to notice and/or react. Since watching the other diver’s beams is now part of your buddy system, any shaking is immediately noticed.

This makes night dives a piece of cake, though I do check from time to time in crowded waters to make sure someone hasn’t “dropped in” and replaced my buddy’s beam. :)

I’m sure that anyone that’s done more than a few night dives has kept track of their buddy via their light, but try and formalize it and you’ll find out that it’s an excellent diving tool.

Roak
 
Hi Roakey,

Actually I used this on my last kelp dive - I think it's great - kelp lends itself to single file diving, so I stayed behind my buddy, who was continually turning around and tangling trying to see where I was. I had a decent sized light for looking at stuff, and I starting shining it on the bottom in front of him every now and again, and voila! No more turning around to check on me, and no more tangles. I'm surprised it wasn't mentioned on my OW course. And it was much easier to get his attention to share discoveries.

Ben
 
Hey Ben & Roak, I agree with you 100%! I find that it is MUCH easier to keep track of my buddies when night diving. We don't have any caves here, but we use our lights to communicate all the time. I LOVE having a BIG light!!!

-kate
 
Yo Roak,how about a primer on standard signals.We use left,right those are easy.To stop and get attention is rapid sideways shaking.To proceed we lift up the beam forward.OH S__T is in a cirle rapidly.Know of any standards other than amongst teams?
 
Roaky--

I want to jump in and say THANK YOU for such good information here and in some of your other posts. This light technique is a good one and I'll make sure to bring it up to my buddies.

Keep this good stuff coming. It's info like this that makes us all better divers and makes us appreciate your expertise.

--TM
 
Hey Roak, how do you guys deal with hi-silt situations? We keep in physical contact in silt. Do you have tugging signals (perhaps like line signals) if light signals aren't an option?

I REALLY want that GUE cave class so I can pick up on some of the more formal things and apply them to wrecks. We've made it up as we went along, but we're very familiar with each other so that helps a bunch.

Mike
 
Tony, about using the lights as a communication tool...

We actually have very few signals using the lights. Hand signals are so much more versatile and powerful that we use those for any detailed communication. Ignoring keeping the light beam in sight for light doubling, we use only three light signals:

Waving of the light back and forth in front of another diver’s field of vision: “Attention.” This usually causes the front diver to turn around and some communication is carried out via hand signals in the penumbra of the light.

Shaking the light rapidly back and forth in front of another diver’s field of vision: “Emergency!” This usually causes the front diver to turn around very quickly with regulator in hand, ready to donate in case the emergency is of the worst kind: OOA. It’s better to have the regulator ready and not needed than needed and not ready.

Moving your beam in a circle around the spot where another diver’s light is shining: “OK?” The diver whose beam was circled then moves their light beam in a circle to signal “I’m OK” back. This way you can actually direct an OK? Question to a particular diver.

Note that there is nothing like “up and down is Attention” and “back and forth is Emergency!” Or is the other way around? This is for two reasons. First morons like me can never remember which is which and two, if you’re descending a shaft, what’s back and forth versus up and down? You can get in some screwy positions in a cave and a wreck, so you want signals that are clear and unambiguous (another reason you don’t want a lot of different signals).

A circle, a slow wave and jerky flashing are very easy to differentiate and if you’re not sure what your buddy is signaling, just turn around ready to donate your regulator, what does it hurt? :)

Roak
 
I can't seem to delete a note, so I'll replace it with this text.

LY asked about touch communication and for that I've started another base note.

Roak
 
Originally posted by TexasMike
...and makes us appreciate your expertise.

TM,

On one hand thanks, but on the other, let me make it clear that I'm a weenie technical diver at this stage. There are others on this list that I feel know far more than I. That said, I do try my best. :)

I think this stuff is pretty neat, and I do like talking about it (more than obvious).

And the sum of all the knowledge of folks on this board far outstrips any one contributor; that’s the beauty of a board such as this.

Roak
 
Originally posted by 100days-a-year
Yo Roak,how about a primer on standard signals.We use left,right those are easy.To stop and get attention is rapid sideways shaking.To proceed we lift up the beam forward.OH S__T is in a cirle rapidly.Know of any standards other than amongst teams?
Tony,

I did want to address your emergency signal being a circle. One thing that GUE/WKPP/DIR has been very good at is basing its emergency procedures on “what would a panicked diver do?” And then working forwards from there.

Starting with a panicked diver, they’ll probably be swimming toward you full tilt either swimming with their hands and/or just thrashing them about. This why the emergency signal is a rapidly flashing light -- a panicked diver will probably automatically display such a light pattern. For this reason you may want to rethink your circle as an emergency signal. A panicked diver isn’t going to have the presence of mind to be drawing a circle with their light as they’re going hypoxic (another good reason to rethink it is PADI teaches a circle as being an OK symbol, so you’re in a vast minority :))

This is also one of a myriad of reasons we donate the primary regulator from our mouths -- a panicked diver is going to snatch the regulator from your mouth, not do the calm, collected drawing the finger across their throat and wait while you hand them your octo as your practiced in OW class. If you PLAN on donating the primary from your mouth, if it ever gets snatched away you know exactly what to do (go for the backup around your neck). You won’t even miss a breath!

Roak
 
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