Signalling Device Buddy Link

I have lost sight of my buddy and soldiered on alone, rightly or wrongly, only to find that I meet him on the ascent - because he was there all the time.
That's the magic of tunnel vision, caused by the refraction of your mask in water combined with the effects of low visibility.
Sometimes, if you're not holding hands, you may as well be on different dives.
Martin Parker, the boss of the company that makes Buddy jackets, AP Valves, asked me if I had seen the Buddy Link while I was at the international DEMA show.
It has absolutely nothing to do with his company, but it's an electronic system for keeping tabs on your buddy.
In the tradition of America macerating our language, it is called an "Affinity Device". It allows you to establish whether your buddy is in the affinity, sorry, I mean vicinity.
Well, I suppose that if you have an affinity for your buddy, it's nice to know if he or she is in the vicinity.

The B-Link
The B-Link device attaches to the glass of your mask by way of a suction cap, and is secured by a little lanyard to the mask strap. You position it so that it stays within your peripheral vision.
I suggest that those with low-volume masks need not apply. Your buddy needs one, too.
The B-Link is controlled by a virtual button. This is an indentation in the clear plastic which, when you place your finger there, interrupts an infra-red beam to a sensor within it.
Tapping this virtual button, or holding it, performs different functions.
Once the two units have been mated using this button (and you can mate several units), you can send signals between them while under water. Each B-Link has four LEDs of red, blue, yellow and green. If all four flash, it appears as white.
The B-Link measures signal strength whenever it receives a signal from its mate. When you press the virtual button on yours, it will respond with an LED colour that represents the signal strength from the other's response. Blue and green means that your buddy is there, right behind you, or yellow indicates that he is within range but further away.
Not only this, but it will give between one and four flashes in response to your call, thereby giving you a more detailed idea of the proximity of the other unit. A two-second red means that you are well and truly separated!
The B-Link also has a pinging sound generator, but you'll be pleased to know that you can turn this off before entering the water.
Different tap sequences allow you to send private signals to your buddy. One tap causes the audio tone to "whoosh", while two cause it to pulse on and off. Four taps makes it sound like a police siren.
Each of these is combined with a twinkle. You'll need to prearrange with your buddy the significance of these messages.

In the Water
I felt a bit self-conscious with this thing attached to my mask. It took some convincing to get my impromptu buddy to wear one, too.
You need a mask with sufficient glass area, or the B-Link will obstruct your vision. The little flashing LED light is seen through the sucker-pad mount.
I mused that I could have fitted the second unit to a static anchor-line of a dive-boat and used it as a navigational aid, but it helps to have company when you're feeling a bit of a twit.
Evidently 500 separate channels are available to separate pairs or groups, reducing the danger of coming home with someone else's spouse.
If you think you'll be dazzled by it in low light or darkness, I'm told that it automatically dims.
There is also a blue LED out of the sightline on top. This flashes every four seconds when the B-Link is activated, and is a useful beacon for other divers on a night dive, or in low visibility.
I imagine the colours work well in the murky Californian waters familiar to the designer. In tropical sunshine, I was unable to tell the difference between the colour of the flashes of LED, but I could certainly hear it every time my buddy signalled me.
The problem was that we could either see each other anyway, or we still didn't know where the other was. The B-Link substituted for a privately heard tank-banger. It was quite rewarding to ping it and see my buddy look up from what he was doing 15m away, but in fact it became just as annoying as a frequently used tank-banger.
It obviously works by line of sight, because I lost contact when he went the other side of a big rock.
If the B-Link is intended to spare you from having an out-of-buddy experience, I'm not sure it's worth the aggravation of the little LED continually flashing in the corner of your vision, or the cost.
If you found a set in your Christmas cracker you'd be well pleased, and have fun with it for the rest of the evening, but this could be the solution to a problem that doesn't really exist.

Recharging
This is done every few dives (the maker claims 10 hours' duration for one charge) by plugging into the USB port of your computer with the aid of the adaptor supplied. Otherwise you can recharge the B-Link from a single AA battery, and the hardware for this is supplied too.
It is slightly irritating that you need to charge each battery separately, because this tends to make you cut short the charging process on one of them.

COMPARABLE PRODUCTS TO CONSIDER:
Tank banger, £10
Dive Alert Plus, £55
The lamp you already own!

SPECS
PRICE US $350
BATTERY Rechargeable lithium polymer
DIVES PER CHARGE Approx 10
OPERATIONAL RANGE 30m plus
WEIGHT OF ONE UNIT 19g
INCLUDED Two units, two lanyards, recharging station and connections, Pelican case
WARRANTY Five years
CONTACT www.buddy-link.com
DIVER GUIDE