Radar Reflective Patches on Drysuit

[miketsp]

Radar reflecting stick-on patches??

What matters to a radar is the apparent size or radar cross section, in other words how much of the radiated signal is effectively returned. Flat surfaces act like mirrors to radar waves so unless the surface is perpendicular to the signal, this is not reflected back to the receiver. Even a large sheet of metal, if almost parallel to the signal will reflect nothing. That's why stealth aircraft are full of sharp angles (carefully arranged not to form corners) and not curves.
So to achieve a good reflection almost all radar reflectors are made of 3 perpendicular planes interlocked to return the signal where it came from by means of a double reflection. See examples here:
http://www.marisafe.com/Store/ViewCategories.asp?CID=10800000
For streamlining the reflectors may be mounted in tubes or balls.

There is a more modern device called a Luneberg Lens which does the same thing without the metal sheets. See:
http://www.buoys.com.au/luneberg.html

Fish finders are normally sonar - sound waves not radio waves.

 

[Mako Mark]

Oh, and cancun_mark: you're a sick puppy. Can I get one with a training agency logo?

Im sorry, I couldnt help myself and I cant believe it took six posts for anyone to call me on it..

 

[String]

Better than avalaunche markers, you can get proper oil filled EPIRBS for if things get really bad to aid in location (most are the 406mhz satellite based method).

The problem there is if you are just separated from the boat and expect a wait to be picked up or need help being spotted do you REALLY want to start a full scale SAR for you ?

Someone else mentioned mobile phones - coverage is "ok" but not great out to see/coastal waters but i dont know of someone whose mobile phone died when he accidentally took it under in his undersuit pocket. The pressure messed up the LCD display totally and permanently
Another idea ive seen mentioned is a marine radio turned on and set to ch16 in an undersuit pocket that you can key by pressing the drysuit. Could be handy for telling your boat where you are if its not immediately obvious.

There're plenty of alternatives around and its a good idea to carry a different ones like reflective patches, strobe, torch, some people carry a CD as a reflector, air horn etc.

 

[miketsp]

some people carry a CD as a reflector,

Marscuba made a post with a link showing the inefficiency of CDs as signalling mirrors:
http://www.scubaboard.com/showpost.php?p=635162&postcount=14

 

[Morg_NZ]

Better than avalaunche markers, you can get proper oil filled EPIRBS for if things get really bad to aid in location (most are the 406mhz satellite based method).

The problem there is if you are just separated from the boat and expect a wait to be picked up or need help being spotted do you REALLY want to start a full scale SAR for you ?

Someone else mentioned mobile phones - coverage is "ok" but not great out to see/coastal waters but i dont know of someone whose mobile phone died when he accidentally took it under in his undersuit pocket. The pressure messed up the LCD display totally and permanently
Another idea ive seen mentioned is a marine radio turned on and set to ch16 in an undersuit pocket that you can key by pressing the drysuit. Could be handy for telling your boat where you are if its not immediately obvious.

There're plenty of alternatives around and its a good idea to carry a different ones like reflective patches, strobe, torch, some people carry a CD as a reflector, air horn etc.

Yeh I mentioned the cell phone idea....my point was to floor some ideas that might be usefull or adaptable:dazzler1:
NO WAY AM I SAYING THAT A MOBILE PHONE IS A RECOMMENDED SAFTEY DEVICE FOR DIVING OR SIMILAR WATER SPORTS.

Now that that's done..........maybe someone else has an idea

 

[cool_hardware52]

My question concerns the Solas reflective patches.


Does it become waterlogged after exposure to depth?

The retroreflective piping, tape, etc. very commonly used on BC's and wings is in fact totally ineffective when wet. All these produces use exposed glass beads (like a movie screen) to reflect light, when wet they just don't work at all. The "piping" on your wing will help you find it a dark garage with a flash light, but that's about all.

The "Solas" products put a clear cover over the glass beads. This is intended to keep them dry. It does reduce the reflective properties quite a bit, by more than 50% if IIRC.

The problem we found was there is an air space under the clear vinyl cover, that is subject to flooding at depth. 3M will tell you the Solas product is primarily for life jackets, i.e. subject to water splash, and perhaps a few feet of depth.

Any sewing of the Solas product of course provides many holes in the clear cover.

We tried testing some Solas patches, but abandonded the idea when we started to grow "a potential replacement for penicillan"
after a few trips to depth.

What has been your experience with the Solas Patches?


Thanks,



ch

 

[fldivenut]

Another idea ive seen mentioned is a marine radio turned on and set to ch16 in an undersuit pocket that you can key by pressing the drysuit. Could be handy for telling your boat where you are if its not immediately obvious.

There are actually spearfishermen that drift dive of the coast here that has a portable GPS and VHF radio with them so they can call the boat if the boat lost them. They store the gear in a water tight container. Both the GPS and VHF are water proof but not at depth.

--A

 

[ChrisA]

Can anyone provide some insight on the use of radar reflective patches on drysuits (other than the obvious "they reflect radar") and tell me why and when I would or should need them?

Thanks.

In theory itwould make you visable on a radar. Without some kind of reflector a diver would not show up at all.

But then...

1) Any reflector sewn into a suit would have to be very small and flat. Small and flat is a very poor reflector. what you want is big and three dimensional with some 90 degree instersections

2) I doubt a little patch would be any more effective then a scuba tank which you already would have

3) A reflector the size of a scuba tank would not show up very well on any radar because it is too small, to low to the water and the "wrong" shape. any patch could not be as big as the tank. I would expect a good radar could "see" a scuba tank that was a few hundred yards away if the operator was looking for one. To be seen miles away would require a reflector about the size of your head and a few feet above the water.

4) do you realy think those drunks driving speed boats even have radar or would even know how to use it?

 

[HarleyDiver]

2) I doubt a little patch would be any more effective then a scuba tank which you already would have

Don't you get tired holding your tank over your head, out of the water? Radar does not see underwater. Thats what sonar is for.