Helium as an option?

[lobstah]

Marker itself might be too heavy to be carried by He. Let alone to be meaningfully controlled from UW.

 

[Scott L]

Marker itself might be too heavy to be carried by He. Let alone to be meaningfully controlled from UW.

I do not believe the OP indicated the marker would be deployed under water...

 

[Tigerman]

Depending on the form of which the helium would be it wont neccesarilly be much lighter than if the canister was filled with air (o2)..

 

[ScubaDadMiami]

ScubaDadMiami (Howard Packer) wrote an article appearing in one of the major diving publications (Alert Diver [DAN] I believe) on open ocean signaling methods which refrenced the use of a simple mylar party ballon that could be inflated with helium then tethered by line & sent high enough for radar to detect. I will work on locating the peice later today...

CCR Dive Training, LLC

It appeard in Advanced Diver Magazine, Issue 31, which is available as a single issue back order from their web site, Advanced Diver Magazine.

 

[reefduffer]

A couple of years ago while thinking about a radar-reflective SMB reported here http://www.scubaboard.com/forums/re...3968-radar-reflective-smb-safety-sausage.html, I found this paper, which I referenced in that write-up:

The Rescue Wing: Design of a Marine Distress Signaling Device.
Tomas Melin and Sandi Sefi
Royal Institute of Technology, Stockholm Sweden 2005
Proceedings of IEEE OCEAN2005, Washington DC, USA, September 2005.
PDF downloaded from OutBox page for Sandy Sefi
Sort of a combination balloon, kite, visual signal, and radar reflector. Sounds like a great concept, and very applicable to scuba diver rescue, but looks to be so far just just an academic exercise, no product. But the discussion has some more useful discussion of requirements, and some useful references.

 

[deepstops]

It appeard in Advanced Diver Magazine, Issue 31, which is available as a single issue back order from their web site, Advanced Diver Magazine.

Is this something that's been tested?? If so, what were the wind conditions?? From what distance was it visible on typical marine vessel radar system??

I'm just wondering because I had a manufacturer tell me the SOLAS tape on their SMBs was "reflective to radar" but when they actually looked into it, it's only reflective to light.

 

[Rhone Man]

I remember someone telling me that in the Red Sea people attach old CDs to the top of their SMBs because that it supposed to make them radar reflective or some similar such thing.

 

[Teamcasa]

http://www.scubaboard.com/forums/ge...ignalling-equipment-searchers-point-view.html

 

[kanonfodr]

I remember someone telling me that in the Red Sea people attach old CDs to the top of their SMBs because that it supposed to make them radar reflective or some similar such thing.

Radar reflectivity is a product of many factors including material type, shape, and coating. That's why the Stealth fighter looks so freaky, the aircraft's coating does absorb some radar but for the most part the aircraft's shape reflects very little radar energy back to the source. Conversely. the fuel truck that gasses up that aircraft when it's parked has a Radar Cross Section that's about 11,000 times greater than the aircraft. Think Tweety Bird vs a Jumbo Jet.

It could very well work, I've heard of AWACS aircraft patrolling the Gulf of Mexico picking up trashbags floating in the water so a floating SMB with a cd attached could very likely be picked up on radar. The problem for the searchers would be differentiating the return of your radar-reflective SMB from the surrounding waters, which certain systems' software may just cancel out anyway to produce a cleaner readout to the operator.

Peace,
Greg

 

[JanK]

Radar reflectivity is a product of many factors including material type, shape, and coating. That's why the Stealth fighter looks so freaky, the aircraft's coating does absorb some radar but for the most part the aircraft's shape reflects very little radar energy back to the source. Conversely. the fuel truck that gasses up that aircraft when it's parked has a Radar Cross Section that's about 11,000 times greater than the aircraft. Think Tweety Bird vs a Jumbo Jet. [SNIP]

An amusing (if unfortunate for the creatures involved) fact: Not only does it reflect very little radar energy, as in about the same ammount as a small ball bearing, the same goes for sound waves.

In the first Gulf War they would find dead bats around F117 airplanes in the morning. The planes were invisible to the bats' echolocation system and they would simply fly into them and die from impact.

And during testing of the radar reflectivity during development, there was an incident where the reflectivity shot up and nobody could figure out why until they saw that a bird had crapped on the model and mucked up the geometry.

Incidentally, the F117 is all angles and flat surfaces because at that time the computers weren't powerful enough to deal with the calculations for curved surfaces, so they had to use just flat surfaces.