Fixing radar reflector to backstay

[graham]

The only sensible place for an octahedral reflector on my boat is hanging on the backstay.

She has twin backstays and I can get it to hang correctly in the "catchwater position" by using several bits of string to hold it on to the stay plus lines down to the pushpit to stop it swinging about.

Inevitably it slips a bit especially in rough weather..

Anyone made a bracket that could be attatched to the backstay .A picture would be great if you have.

Thanks in Advance Graham.

shown here in the "not quite right" position.

 

[ianc1200]

Graham

Thread drift, but how did you support the reflector on Vega? I've taken to tying it on Sea Moon on the backstay, just above the pulley, but it bangs around and is never in the right position, or high enough.

regards

IanC

 

[tarik]

Whilst on the subject of reflectors - what if I sprayed mine with hi- vis orange would it adversely effect it????

 

[graham]

Hi Ian .Had similar problems on Vega also. I have been thinking of either a bracket fixed to the back stay or maybe a pole to mount it on.

We sailed through some fog patches recently which focuses your mind on the subject.

 

[exfinnsailor]

We passed a Dutch boat with one stuck bolt upright on a pole .. Looked very neat it did . Someone had spent a lot of time but totally missed the point of how they work .. Think you might find that they work better if they spin round a bit .. Bounces the signals off better .. Mind you after reading some of the reports you may as well just throw it at them .. They would probably see it then .. Would not try and clamp anything to the back stays as all it will do is crush the wire .. What about a re-think .. Short top backstay and two down from that .. Will give you something to fasten a block to .. You can then make it go up and down for use when needed .. /forums/images/graemlins/smile.gif .. Ps Painting them any colour will not be detrimental to something that does not work that well in the first place ..

Which Ones Work

 

[VicS]

I have mine mounted permanently between the twin backstays.

It is mounted on wooden battens using little aluminum brackets so that it is at the correct angle behind the stays. The battens are clamped to the stays with aluminium plates and self vulcanising rubber tape.

Thought has to be given to the arrangement so that the topping lift can never become trapped and a fair amount of calculation to get the battens the right length.(no problem so long as you can remember the trigonometry you learnt at school)

It was first fixed in 1979 and remounted in 2001 because it was slipping slightly. It has otherwise been 100% successful as far as the mounting is concerned.

I have to say that it is only a small one, less than the recommended size. A "normal" sized one would I think need a support from the masthead crane, but that would be no problem.

Maybe I can get a photo or two later this week or next weekend. The boat is ashore and the mast down so access is only restricted by the 80 miles or so between home and boatyard. I don't remember the details well enough to do a sketch.

 

[charliespan]

Bartons make some neat plastic clamp-on cleats for stays.
One type is a normal cleat , another has "half a cleat" and a ring.
Although designed for flag halyards , these might work for you.

Non-damaging as far as I can tell.

Barton Cleats

 

[Refueler]

Metal strip with open ring ends. Bolt reflector to strip centre. Drop strip ends over stays and let it slide down till ring ends are tight on the stays. No need for clamps, string or other. Easily removed by pushing affair up and of the stays.

 

[rob2]

Yes, there was a company who made backstay mounts for such things.they had a triangular braced form so that the lower leg held the mounting platform level and they were intended to be histed up and down as required. Damned if I can remember the name of the company, though!

Painting the reflector will have no effect on its performance as a reflector - its the metal that does the job! As it should ideally be showing the corner reflectors to the horizon at all times, it probably explains why a damped gimbal mounting is reckoned to be the best by the manufacturers. This could be achieved on a backstay mount (in theory, at least) by suspending an equal weight below it to keep it upright, damping its swing.

Like others have said, they don't always work at the necessary angle, so getting it up at all is a start - refinements to the mount is a secondary consideration. Incidentally, when the Yanks tested a number of reflectors, they did an octohedral in the "wrong" orientation and it gave higher peaks, but wider spacing.

Rob.

 

[graham]

"Thanks to everyone for the suggestions.

The reason I have an octahedral is I know they work. Theres an outfall buoy near us that shows very poorly on radar and has been crunched by ships a few times in the past.

On the last occasion it was flattened a local fishing boat was paid to temporarily mount an octahedral reflector on a pole on the buoy held on temporarilly with wire.

Result was a hugely improved radar target far better than any of the other buoys,it would not allways be at the ideal angle either as Spring tides would have the buoy leaning over at 20°but still showed up well.

Sorry for the thread drift ,Im now thinking along the lines of a piece of plywood between the two backstays with aluminium strips bolted on the end that could be wrapped around the stay and pulled down to lock in place.

 

[VicS]

[ QUOTE ]
The reason I have an octahedral is I know they work

[/ QUOTE ] Trouble is they work well when in the correct rain catching orientation but not so well when tilted over away from that angle as on a heeled sailing vessel.

The QinetiQ report produced in the wake of the Ouzo disaster is relevant reading HERE

 

[Babylon]

[ QUOTE ]
The only sensible place for an octahedral reflector on my boat is hanging on the backstay.

[/ QUOTE ]

Why not hoist it (when needed) on a signal halyard right up to the underside of a spreader?

That way it would be higher giving a greater 'range' and would hang perpendicular the fore-and-aft line giving a more correct vertical angle. With a little slack in the halyard it would also hang more vertically when heeled and you could dampen any swinging with shock-cord.

Any potential snag or chafe on the genoa leach seems unlikely, and it won't make that much difference to windage aloft.

Presumably this set-up would also apply to most other designs of radar-reflector.

 

[LittleSister]

[ QUOTE ]

Why not hoist it (when needed) on a signal halyard right up to the underside of a spreader?

[/ QUOTE ]

Because this is what we do at the moment and it is fairly hellish with
the reflector crashing around - especially with an octohedral and its sharp edges. The reflector moves much faster and further than the boat , and I can't think of any way you'd achieve the desired damping without a lot of weight.

We bought an Echomax to 'replace' an octohedral. Currently hung on signal halyard from under spreader, with bird's nest of cords and bungees to shroud and lower shroud to keep under some degree of control. Though not as sharp and nasty to its surroundings as the octohedral, I can't wait to get it permanently mounted on mast (when the mast is down for the winter).

We actually intend to retain the octohedral, and mount it between the split backstays, so I'm pleased to hear the various suggestions above.

My reasoning is that I believe the mast shields the reflector (of whatever type), rendering it less effective from particular directions (in this case from aft). So having one reflector on front of mast and another behind it (on backstays) will, hopefully, give me some radar visibility from all directions, as well as a stronger reflection from angles where they are both 'visible'.

 

[VicS]

[ QUOTE ]
as well as a stronger reflection from angles where they are both 'visible'.


[/ QUOTE ] I am afraid that is not necessarily the case. It is possible for the echos from two reflectors to be completely out of phase and actually cancel each other out!