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-   -   Remove (trilens) radar reflector from mast? (http://www.sailnet.com/forums/electronics/91624-remove-trilens-radar-reflector-mast.html)

MastUndSchotbruch 09-02-2012 10:51 AM

Remove (trilens) radar reflector from mast?
 
Couple years ago I installed a Luneburg radar reflector (specifically, the medium size Trilens) on my mast. Pretty high, maybe 40' up. Based on the specs I expect that it works pretty well though I don't really have any actual confirmation. I sail in the Chessie and I was never caught in fog but I want to be on the safe side.

BUT: This thing is a perfect halyard catcher! Two or three times each year, something gets wrapped around it and, given the height were it's at, it takes me an hour or three of fiddling to sort it all out.

I am considering to take the reflector off the mast and to just hoist it on a flag halyard when I need it.

This will probably make the reflector bounce around a bit more. Will that affect its reflectivity? Given the supposedly rather isotropic radiation characteristics of a Luneburg reflector, theory says it should not.

Thoughts?

ParadiseParrot 09-02-2012 03:31 PM

Re: Remove (trilens) radar reflector from mast?
 
Recent studies have shown they have little value. Take it off.Sell it. Get AIS.
FWIW.

jrd22 09-02-2012 04:08 PM

Re: Remove (trilens) radar reflector from mast?
 
AIS only shows boats equipped with a class B transmitter, it's no substitute for having a reflector or radar IMHO. For the majority of boats out there that just have radar or an AIS receiver you'll just be an accident waiting to happen if they can't see you. The Davis Echomaster(?) has consistently been shown to be the best (and one of the cheapest, and it stores flat) reflectors available and you could just hoist it on the flag halyard when/if needed.

PorFin 09-02-2012 05:16 PM

Re: Remove (trilens) radar reflector from mast?
 
Quote:

Originally Posted by ParadiseParrot (Post 917125)
Recent studies have shown they have little value. Take it off.Sell it. Get AIS.
FWIW.

Would you care to post where to find the results of these recent studies?

MastUndSchotbruch 09-02-2012 07:03 PM

Re: Remove (trilens) radar reflector from mast?
 
Quote:

Originally Posted by jrd22 (Post 917136)
AIS only shows boats equipped with a class B transmitter, it's no substitute for having a reflector or radar IMHO. For the majority of boats out there that just have radar or an AIS receiver you'll just be an accident waiting to happen if they can't see you. The Davis Echomaster(?) has consistently been shown to be the best (and one of the cheapest, and it stores flat) reflectors available and you could just hoist it on the flag halyard when/if needed.

I don't know which study you are referring to. Practical Sailor found that the medium and large trilens is far superior to the Davis. See http://www.tri-lens.com/practical_sailor.txt for a copy of the 2001 report. Quotes:

"The Tri-Lens easily out performed all other reflectors in the 1995 test."

"It costs more than the Davis Echomaster, but out performs it. If you're in the market for a passive radar reflector, we recommend the Tri-Lens."

jrd22 09-02-2012 08:00 PM

Re: Remove (trilens) radar reflector from mast?
 
Mast- I should have qualified that with "from what I recall seeing in Practical Sailor":-)) My point was that if you rarely encounter fog there isn't much need for a permanently mounted reflector so something like the Davis might be a good alternative for the few times you need it.

ParadiseParrot 09-02-2012 09:04 PM

Re: Remove (trilens) radar reflector from mast?
 
Quote:

Originally Posted by PorFin (Post 917151)
Would you care to post where to find the results of these recent studies?

http://offshore.ussailing.org/Assets...ctor+tests.pdf

beth and evans discussion of above.

http://www.bethandevans.com/pdf/Rada...tor%20test.pdf

Practical boat owner magizine discussing FAIL.

Ouzo report: Radar reflectors fail test | News | Pbo

USSSAILING,,,,,,,Passive's FAIL....

only active reflector showed any use.

http://offshore.ussailing.org/Assets...r+Test.pdf.pdf


Given how and when large ships use radar Passive radar reflector have only psychological use.If it make you feel good then fly one but the OP's installation is causing more harm to his safety than a reflector could add to it.

Your own radar with AIS is the way to go....Active reflectors seem to work reasonably well but for there cost and power use i would just my own radar.

Several studies where undertaken by independent agencies because of rundown incidents with large shipping. The results are all more or less the same.

ParadiseParrot 09-02-2012 09:06 PM

Re: Remove (trilens) radar reflector from mast?
 
Quote:

Originally Posted by MastUndSchotbruch (Post 917182)
I don't know which study you are referring to. Practical Sailor found that the medium and large trilens is far superior to the Davis. See http://www.tri-lens.com/practical_sailor.txt for a copy of the 2001 report. Quotes:

"The Tri-Lens easily out performed all other reflectors in the 1995 test."

"It costs more than the Davis Echomaster, but out performs it. If you're in the market for a passive radar reflector, we recommend the Tri-Lens."


Better doesn't mean effective....sorry.

Practical sailor did not take into account HOW shipping uses radar only how they performed relative to each other.

ParadiseParrot 09-02-2012 09:58 PM

Re: Remove (trilens) radar reflector from mast?
 
Sea-Me Crew Safety. ISO 8729 Part 2


States no current passive reflector meets the new 2009 updated standard.

ParadiseParrot 09-02-2012 10:03 PM

Re: Remove (trilens) radar reflector from mast?
 
Admitting they dont work the UK government modifies Solas for rec boat under there flag.
7.) Owners and operators should note that under Regulation 18 equipment meeting the requirements of Regulation 19 must be type approved. However by virtue of Regulation 1.4, the Agency allows United Kingdom vessels which are too small to fit reflectors meeting the IMO standards to fit equipment suitable for the type and size of vessel.


UK government .........


One should be installed for the benefit of your insurance company so you appear to try and meet SAS requirements(which you cant)
Put it up where it will do the least damage.

Solas
2.1.7 if less than 150 gross tonnage and if practicable, a radar reflector, or
other means
, to enable detection by ships navigating by radar at both 9
and 3 GHz;


ISO 8729-1-2 Performance Standards for Radar Reflectors effective 22nd July 09 are shown below.
The reflector must have a Stated Performance Level of 7.5M2 measured in meters radar cross section (M2RCS) of at least 7.5M2 in X band and 0.5M2 in S Band mounted a minimum 4 meters above sea level.




The following notes gives further guidance on the choice of a radar reflector for small vessels and supersede Merchant Shipping Notice M.1638.

5.) It should be noted by Master and Operators of all vessels that even the 10 m2 reflectors referred to above will be difficult to detect in sea clutter on radar displays. Masters of all vessels are reminded that this should be taken in to account when setting lookouts and determining safe speed as required by Rules 5 and 6 of the International Regulations for the Prevention of Collisions at Sea.


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