radar reflectors

[ebb]

Have not researched this subject. This only starts a discussion if so desired.

If I remember A338 came with a knocked down Davis 'emergency' reflector. It got disappeared.
Recently been figuring out what might be on the masthead and what number of wires will be in the mast. I checked by Tim Lackey's Triton381 site where I believe he is discussing his first mast and has his usual supporting photos. He had a slick looking tube radar reflector attached near the top called a Mobri.
It looks like the kind of aerodynamic design I could live with.

So I poked around and discovered Defender sells one for $90. At the same time I ran into another tube affair called the Sea-Me Radar Reflector. Unlike the Mobri which is "passive" and reflects back to the ship's radar that is trying to run you down signals bouncing off pieces of aluminum in its tube....
The Sea-Me takes those signals, amplifies them and transmits them back to the source. Supposedly this enhances your meager reflection back at the ship's radar. They call this an "active" reflector. It requires wire in the mast and needs 150mA when transmitting.

I haven't found this product here while trying to find out its cost. Looks like it's about $600 in Europe.
On MyBoatsGear.com there is a 'review' (with links) of a copycat Echomax Active X Radar Reflector said to be in the same price range.


SO OK. This kind of thing is well beyond most peoples budgets. So where does our compromise stand? That old Davis?

(google) Report by QinetiQ "Performance Investigation of Marine Radar...
www.ybw.com/pho/pdfs/radar_reflectors.pdf
[sorry the url is faulty]

The Davis - Mobri - Plastimo 16" - Trilens - Sea-Me - Echomax230 - Firdell Blipper210-7 - Plastimo 4" tube - are among those tested. Seems to be an impressive testing model. Some of these reflectors totally new to me. You will discover that as soon as relectors in the rigging or on the mast go beyond a 10 degree 'lean' they loose effectiveness - some radically.
Only one real winner: Sea-Me 'active'
Only passive reflector is the large ungainly Trilens. Barely passes, we A/Cs couldn't find a place for it anyway!
The Davis reflector is an also-ran and is considered dangerous by QinetiQ because you and I will want to depend on it when it cannot do the job.
Check it out.

Feedback....?

[c_amos]

I have come to the same conclusion... There is nothing worth mounting that added any appreciable radar cross section without adding too many boat units or windage.

The Ariel is nearly invisible to radar in anything but very calm conditions. Having spent many many hours on watch on the bridge of ships with VERY good radar anything shorter then a couple meters is usually filtered out with the reflections from the waves.

Radar signature increases as the product of the square of surface area. The waves that pop up in the 12.36 microseconds (a mile) that it takes that energy to travel back and forth are going to add a bunch of 'junk' to the display... and are generally filtered out.

No one is looking at that radar, and it won't identify targets in the CPA alarm range that are below the selected threshold.

The fancy tubes and geometric shapes can not do anything to be bigger then they are... the can only increase the percentage of reflection at a given angle. You would have to go BIG, go ACTIVE, or go without IMHO.

CARD / AIS is going to do much more to keep you out of harms way then a radar reflector. IMHO.

[ebb]

CARD/AIS:
We'll have to wait til it comes down to our level, weight and price.
Like you say, the other guy has to have his radar ON. And the watch has to be looking at it rather than Playboy.

Instead of patched together electronic geek links with iphones and pc's, I'd prefer a stand-alone like a fish-finder that could be on without much battery draw and would give direct immediate info. FIVE mile info.
Did run across a CARD device that came with a fixed compass-like image on a separate screen that showed other vessel proximity with moving red bars toward a center green target (the boat). Seemed rather primitive so didn't copy. Believe it was around $1400.
With experience it would be useful, I suppose.
In a dense fog, or light fog, only the experienced would find it useful.

It's not directional in that it can't show the direction of the vessel relative to your picking up his signal. Only that SOMETHING is getting closer from port/starboard/stern or front. For angle info you need a google/ LIVE shipping aid (there are sites) and a computer screen. Moving zooms and arrows on a screen while paranoid at the tiller is NOT what I'd want though.
Want to SEE vessels moving on a screen relative to me - like fish below the boat on a finder. A GPS/GOOGLE/CARD combo - with built in triangulater to predict run-down and avoidance. RADAR. Radar needs an update - been around since 1941.

Why radar has to have a white tub in the rigging to make it work instead of a neat mobri tube I'll never know.

Defender has a WWII surplus radar reflector for $5.

[carl291]

ebb,
Some times just operating under the "big ocean,little boat" theory offers as much collision avoidance. We got nuclear subs surfacing into other vessels or running into the continental shelf, cruise ships groundings and collisions, tanker groundings, tugs losing tows and all these ships have electronics we couldn't begin to afford or if we could would sink our boats.:D
From what I've read , the bow wave of a large vessel will push a smaller boat off only delivering a glancing blow:rolleyes: I've read somewhere a cruiser carried several sticks of dynamite and would light a fuse and throw a stick overboard to get the attention of a larger ship bearing down on him, claimed it always worked:eek:
I think the CARD system has the most potential, maybe soon they will be as cheap as police radar detectors!