Surface signalling mirror

[Zero]

After disembowelling a hard drive hard which caused me way too much grief (another story), I noticed the round, thin, reflective platters sitting on the table. I wondered if these could be used as a surface signalling device. It has a nice smooth hole in the centre with smooth edges which would prevent BC damage.

Has anyone tested how well this media holds up in salt water? Considering the number of dead drives sitting on my workbench, it’s worth conducting a few tests.

 

[Boogie711]

Probably "not."

There's a link floating around here showing relative reflectivity of a proper signal mirror versus another commonly believed substitute - a CD. People are fooling themselves and risking their life by taking a CD and thinking it works as a signal mirror. Will it work? Sure. Does it work as well as a proper signal mirror? It's less than half as effective.

And my signal mirror floats, and it cost me about $5. For a $5 bill, I'd sure hate to see the Coast Guard plane fly overhead and disappear into the horizon. I doubt very much I'd say "Well hey, at least I saved $5."

Get a proper signal mirror - that's my advice, anyway.

 

[cdiver2]

After disembowelling a hard drive hard which caused me way too much grief (another story), I noticed the round, thin, reflective platters sitting on the table. I wondered if these could be used as a surface signalling device. It has a nice smooth hole in the centre with smooth edges which would prevent BC damage.

Has anyone tested how well this media holds up in salt water? Considering the number of dead drives sitting on my workbench, it’s worth conducting a few tests.

They are no good. There has been a couple of long threads on this if you do a search. Get a mirror...there cheap enough

 

[WVDiver]

Probably "not."

There's a link floating around here showing relative reflectivity of a proper signal mirror versus another commonly believed substitute - a CD. People are fooling themselves and risking their life by taking a CD and thinking it works as a signal mirror. Will it work? Sure. Does it work as well as a proper signal mirror? It's less than half as effective.

And my signal mirror floats, and it cost me about $5. For a $5 bill, I'd sure hate to see the Coast Guard plane fly overhead and disappear into the horizon. I doubt very much I'd say "Well hey, at least I saved $5."

Get a proper signal mirror - that's my advice, anyway.

Have not seen a mirror like the one you have described. Do you have a link for it?

 

[Boogie711]

Have not seen a mirror like the one you have described. Do you have a link for it?

This is one of the more expensive ones I've seen. Mine was like, $7 Canadian or something ridiculously cheap.

http://www.survivalunlimited.com/survival_misc/starflash.htm

 

[WVDiver]

This is one of the more expensive ones I've seen. Mine was like, $7 Canadian or something ridiculously cheap.

http://www.survivalunlimited.com/survival_misc/starflash.htm

Pretty cool. It doesn't say it floats but I have seen similar ones. Mine is hard metal and it will not float. Maybe I will try one of these. Mine has gotten pretty scratched up over the years. I have used it in the past. Not really for dire emergencies but it has come in handy a few times.

 

[Doc Intrepid]

One thing to keep in mind is that the plane thats searching for you will be moving. Likely at least 130 kts or faster.

A proper mirror can be aimed. If you take it outside on a sunny day, pick a spot up on the foliage of a tree and attempt to flash that precise spot with regular flashes. To do this you need to aim through the mirror and pass the bright dot regularly over the specific location on the tree foliage. You'll discover that while it isn't brain surgery it might take you a bit to be able to flash the location precisely.

And that location isn't moving at better than 130 kts per hour or more.

To flash an aircraft you need to be able to move the bright dot back and forth over the aircraft as its moving across your horizon.

Trust me, you'll aim that dot much more precisely onto a moving aircraft with a proper mirror than with a CD or some part you pulled out of the guts of a computer.

FWIW. YMMV.

Doc

 

[Zero]

Probably "not."

There's a link floating around here showing relative reflectivity of a proper signal mirror versus another commonly believed substitute - a CD. People are fooling themselves and risking their life by taking a CD and thinking it works as a signal mirror. Will it work? Sure. Does it work as well as a proper signal mirror? It's less than half as effective.

And my signal mirror floats, and it cost me about $5. For a $5 bill, I'd sure hate to see the Coast Guard plane fly overhead and disappear into the horizon. I doubt very much I'd say "Well hey, at least I saved $5."

Get a proper signal mirror - that's my advice, anyway.

Yes, I've seen and tested the poor reflective qualities of standard CD media. In fact, this media does not seem very durable as well. I wouldn't like one fracturing in a pocket or gear bag.

The media for hard drives is entirely different from that of a CD. The ones I was able to salvage were aluminum with a mirror like surface (seen attachment). In fact, this media was quite durable after the repeated bounce test. It took quiet a bit of force in a vise to bend it as well. I've dropped a couple in water which has a salinity greater than ocean water to see if they corrode.

I know $5-$7 isn't too much to spend on personal safety, but I have a workbench full of drives containing free signalling mirrors. I also like the fact that I'm recycling something that usually ends up in the garbage.

YMMV

 

[ScubaToneDog]

Old CD's work pretty well...the media was sandwiched between plastic...the newer ones have the backside of the media exposed and its not as reflective as they used to be. While a hard drive disc would make a suitable signaling mirror, I would go with the Starflash type mirror for use in the water. A Starflash mirror or any commercially available mirror with an illuminated sight is the more sensible way to go. A CD a HD disc or even a highly polished metal mirror with a sight hole, needs two hands to sight and hit a target...hard enough on dry land, a pain in the butt in the water.

I say go for it, but realize the difficulty and the limitatons. With practice it may be a suitable signal device.

 

[lamont]

http://www.equipped.com/signal.htm