Review by: Bill Dawes – 7/06/2023
Build Quality: 8/10 – Function: 10/10 – Usefulness: 10/10
Also known as a heliograph, this is one of the most under-rated emergency comms devices. It’s tiny, weighs nothing, it floats, it’s completely impervious to getting wet, yet you can use it to signal really effectively to anyone or anything in your line of sight, whether they’re one mile or 50 miles away. Tuck it in your shorts pocket or the pocket in your buoyancy aid, and you won’t even know it’s there, until you need it.
Using a heliograph is incredibly straightforward, although it does have the twin requirements of a) sunshine, and b) the object or person you wish to signal to being in the same half of the horizon as the sun. You simply sight through the hole in the back of the device (ie the non-mirrored side), and hold your finger up so that the tip is exactly in line with the distant recipient of your signal. Now move the mirror around until you have lit up your finger-tip with the sun’s reflection. Hold it steady, gently lower your finger so it’s just below the target, and hopefully your mirror is now dazzling that boat, plane or person in the distance. By moving the mirror just very slightly, you can make it into a message – three ‘dazzles’ with a half second break in between, and repeat. Or if you’ve really got control of it, do the old short-short-short-long-long-long-short-short-short SOS transmission.
Practice in the garden before you add it to your emergency kit. It’s a really cool piece of gear and unbelievably effective for such a simple little device. I’ve been carrying one for 25 years now (I had it in my windsurfing emergency kit before paddleboarding came along), and it’s still in perfect working order. And yes, I’ve used it a couple of times ‘for real’, and it has worked flawlessly each time.
The only thing to be aware of from a maintenance point of view is that the mirror will lose some of its effectiveness if it gets scratched. So if you keep it in a light cloth bag or even just a fold of material, it’ll last better. (This is why I’ve given the slightly lower rating for the build quality for this standard model. You can get more expensive ones with a toughened glass mirror, but honestly, it’s probably not worth the extra expense.)