Position of radar reflector

[roycruse]

Originally Posted by Simon Hawkins

Under Solas it is a requirement for sea going vessels to have a radar reflector. The whole purpose of a reflector is for other vessels to see you, and the bigger the reflector the better.

Doesn't the regulation say "if practicable" I don't consider moving all my factory fitted electronics or having to weld extra platforms to my RIBs A-Frame "practicable".

I could probably do something like Hugh has done here but im sure we will all agree that is pretty pointless (sorry hugh)

http://www.rib.net/forum/attachment....chmentid=17425

[codprawn]

Originally Posted by Scary Des

Go on king of gooogle, prove it
There is nothing on the Trilens website about there performance other than they say they are good whereas Echomax show their results warts and all Des

As I said before I read the tests in various British boating mags who are fairly well established.

The trilens site is crap - they only show the reflector mounted to a mast which looks stupid - it is far better designed for power boats - in particular small ones!!!

[Simon Hawkins]

Yes you are correct it does say "if practical" You can buy smaller reflectors which can quite easily be cable tied to the A-Frame.

Simon

[Scary Des]

Originally Posted by codprawn

As I said before I read the tests in various British boating mags who are fairly well established.....

Oh that’s alright then, I was worried for a moment it was only your opinion Des

[codprawn]

Originally Posted by Scary Des

Oh that’s alright then, I was worried for a moment it was only your opinion Des

I would never buy anything without trying to find out if it's any good first!!!

[DJL]

Polar diagram for the standard Trilens and Echomax EM230.

[DJL]

I've just been through this entire do I/do I not argument with my new boat.

In the end I personally decided not to get an Echomax permanently fitted – reasoning behind this being, lack of space on the top of the a-frame and in this position its likely hood of dropping off. I was going to get a bracket fabricated so it could be mounted on the side of the a-frame, but it would have been quite low. Instead I will fit one of those completely useless 2" tubes (mounted vertically, not horizontally where it would be 100% useless) and will carry an inflatable Echomax (which performs better than the Trilens) for reduced vis/emergency situations.

Although I understand and fully appreciate the Solas V requirements, I think that on the whole, for small pleasure craft a mandatory radar reflector is not as useful as for ex. mandatory VHF.

[Scary Des]

Originally Posted by DJL

Polar diagram for the standard Trilens.

DJL
Isn't that a combined polar diagram of a EM230 (Echomax) and a Trilens and unless i'm reading it wrong the Echomax is out performing the Trilens even in its nulls Des

[DJL]

Originally Posted by Scary Des

DJL
Isn't that a combined polar diagram of a EM230 (Echomax) and a Trilens and unless i'm reading it wrong the Echomax is out performing the Trilens even in it nulls Des

Yes, sorry thats what I meant to say.. and yes the echomax out performs even in its nulls!

[Scary Des]

Originally Posted by DJL

..... Instead I will fit one of those completely useless 2" tubes (mounted vertically, not horizontally where it would be 100% useless) and will carry an inflatable Echomax (which performs better than the Trilens) for reduced vis/emergency situations.....

Don’t quite understand why you are fitting the 2” one but the inflatable reflector makes loads of sense do you know how they are getting that type of performance Des

[codprawn]

From what I remember of the tests(can't find mags) the trilens scored well in actual amount of time visible on screen rather than actual strength - I THINK!!! All I remember about the tests was that the trilens was considered pretty good overall....

Doesn't anyone read any of the boating mags???

[Chris Murray]

Originally Posted by codprawn

From what I remember of the tests(can't find mags) the trilens scored well in actual amount of time visible on screen rather than actual strength - I THINK!!! All I remember about the tests was that the trilens was considered pretty good overall....

Doesn't anyone read any of the boating mags???

Yes!

This was reviewed in TWO magazines, both of which rated the Tri-lens (not necessarily "the best" but for doing what it says on the label. I could look for one of them (I gave the other to Scorpion) but the end result was that it was "visible" a good percentage of the time from virtually all angles - enough to appear on ARPA systems (I think those are the correct initials).

On the strength of these TWO reviews, I ordered the Tri-lens Standard for my boat. It will sit beneath the radome - and should look good too!

No. I am not going to dig out the review. I don't see a lot of point in trying to persuade other RIBnet-ers that one is better than the other. In my case, I was satisfied by the excellent reviews and it looks right on my particular boat.

BTW, I decided not to buy the Sea-Me ... out of respect for my fellow boaters. If you want to blot out the radar image of several other boats in the vicinity, go ahead and fit one!

Chris.

[Shaggy]

Originally Posted by Roy

2. fitted next to an antenna - it will greatly reduce radio reception and transmition in that direction.

Originally Posted by Scary Des

There is no evidence for this:- a)they work on different frequencies b)the reflector is only 400mm high where the aerial is a 1000mm and c)because an aerial radiates around 360 degrees the reflector could at the most shield only 20 or 30 degrees, if it has any effect at all. Des

Des any lump of metal with in the propagation field of an antenna will affect its standing wave ratio which is a measurement of how efficiently your antenna system will radiate the power available from your radio.



Assuming the Radar reflector is made of a lot of meat sheets etc. unless you tune your antenna in place adjacent to the metal object, there will be some impact on the efficiency of the array and therefore impact the gain for reception and its transmission characteristics.



Taking it too the extremes, it could also be extrapolated that due to the miss match caused by the adjacent object in the near field, some of the RF energy would be reflected back down the coax to the final PA stage in the transmitter, which over a very long period of time may result in PA failure.

Having said that I expect this would have to take a very long time, and the reduction in gain will have little impact but one that certainly could be measured and quantified, if you were keen .

[codprawn]

At last I have found the mag I saw the reflector test in!!!

Motor Boats Monthly - July 2005 issue.

Without a doubt the active Sea-Me was the best but at approx £500 so it should be - also has the drawback that it only works on X band - ships often use S band in confined areas.

The full size echomax did very well as did the midi version used on Ribs.

Where the Tri Lens REALLY scored was in time visible 70% for the standard and 97% for the large. - better than either of the Echomax visible 64% and 44%.

The only thing they compalined about with the Tri Lens was the weight - 2.4kgs for the standard one. given it's very low profile not a prob at all on a RIB - only if it's at the top of a mast!!!

So to the people who said that I had put looks before function etc in getting the Tri Lens - WRONG!!! just wasn't going to say too much until I found the article.

IF the review is right the Tri Lens must be the best bet for a RIB....

[Biggles]

Who thinks those Plastimo radar reflectors are absolute tosh.

I saved up my 30 quid and bought the motor boat one which I fitted to my A Frame. First trip out it fell apart but I managed to save all the bits. Its held together with silicone sealant and its made of slippery plastic. Doh.

So anyway I rebuilt it. Two trips later I got hit by masses of spray and a wave and it got snapped in half.

Because I refuse to waste another 30 quid I've now got half a radar reflector.

So if anyone sees a RIB with a really small radar reflector, thats tight old me.

[codprawn]

Originally Posted by Biggles

Who thinks those Plastimo radar reflectors are absolute tosh.

I saved up my 30 quid and bought the motor boat one which I fitted to my A Frame. First trip out it fell apart but I managed to save all the bits. Its held together with silicone sealant and its made of slippery plastic. Doh.

So anyway I rebuilt it. Two trips later I got hit by masses of spray and a wave and it got snapped in half.

Because I refuse to waste another 30 quid I've now got half a radar reflector.

So if anyone sees a RIB with a really small radar reflector, thats tight old me.

If you mean one of those see through plastic tube things they basically said they were crap.

[Scary Des]

Originally Posted by codprawn

.....Where the Tri Lens REALLY scored was in time visible 70% for the standard and 97% for the large. - better than either of the Echomax visible 64% and 44%....

What are you going on about Codders is this some sort of new test you have invented Reflectors are rated by the area they appear on a radar at different angles of heal and there consistence of performance around 360degs. What is this ‘time visible’ test Des

[Alex-341]

Biggles

We have one of those, build quility isnt great no. First one we had the tube fell out of its base. lost at sea. We had to get the same one thoughbecuase the dealer had rivited the base down, this ones doing fine though.

I cant belive that they do nothing, must help in some noticeable way surely?

[codprawn]

Originally Posted by Scary Des

What are you going on about Codders is this some sort of new test you have invented Reflectors are rated by the area they appear on a radar at different angles of heal and there consistence of performance around 360degs. What is this ‘time visible’ test Des

In the test they drove a RIB around in a circle at tickover. A reflector may give a very strong pulse at one angle but almost nothing at another.

Some of the reflectors on test were only visible on screen for as little as 5% of the time - obviously a reflector which remains visible for 70% of the time gives you a much greater chance of being spotted.

Peak pulses may look good on paper but in the real world don't mean so much.

[codprawn]

Originally Posted by zodiac rover

Biggles

We have one of those, build quility isnt great no. First one we had the tube fell out of its base. lost at sea. We had to get the same one thoughbecuase the dealer had rivited the base down, this ones doing fine though.

I cant belive that they do nothing, must help in some noticeable way surely?

To get the best results the tube has to be mounted vertically but even then it has very limited performance - they gave it 1 out of 5.

Time on screen was 7% and clearest echo 3 out of 10.

Remember these were with it mounted perfectly upright and on top of a 4m wooden pole!!!

When tilted it was even worse.