Radar reflectors again.

[Binman]

Having read reports on Plastimo small reflectors not being very good, what could be most suited for my yacht of 7m with a mast of some 24ft height, would mounting on the back stay, be better than mast, only I thought they had to hang vertically, cost wise I hoped I could get one for £130 pounds that would be suitable. Do they have to be connected to a electrical circuit, the only means of charging my battery is by means of a small Honda outboard 5hp, Or by carting a small generator aboard via my dingy, unless I am ashore, then by plugging into the 240v socket I have. I still need power for VHF with DSC nav lights and cabin lights, I intend to use my yacht 2 to 3 times a week in the coming months, Would it be a good idea to leave my generator permanently on board? This will be my first season with my own boat.have thought of a 80 watt solar panel, I have a very small 12v that I leave proped up in the cockpit, when on my trot mooring, but with a big panel I worry it would be stolen.

 

[prv]

Radar reflectors don't use power, they're basically just some cunningly (or not so cunningly) bent bits of metal that reflect the radar waves back where they came from.

Personally with a small yacht like that I'd fit a Plastimo thin tube type on either the mast or backstay to be "road legal" and maybe help a bit, and then concentrate on staying out of the way of anything big and fast

Pete

 

[Iliade]

I have a firdell bolted to the mast. Allegedly it's pretty effective and it's certainly no real inconvenience, but I have a feeling that nothing beats a good old fashioned rain catcher reflector slung under the spreaders.

As prv says, the main thing is to stay out of the shipping lanes whenever possible and keep your ears & eyes peeled for anything else.

If you have not already got one, there's a VHF radio with a built-in AIS receiver (Standard Horizon GX2200C) which offers a bit of peace of mind.

 

[macd]

If you have not already got one, there's a VHF radio with a built-in AIS receiver (Standard Horizon GX2200C) which offers a bit of peace of mind.

...also Radio Ocean (Furuno) RO4800, somewhat less costly.

 

[bbg]

Does your anticipated usage make a radar reflector important? I would be inclined to carry a flat-pack reflector that can be slotted together, with appropriate lines so it is ready to be hoisted in the "catch rain" position and only hoist it if necessary.

If you are not sailing at night or in fog (I know it sometimes comes in unexpectedly) - why do you need a reflector at all? At least permanently mounted?

 

[bbg]

I have a firdell bolted to the mast. Allegedly it's pretty effective and it's certainly no real inconvenience, but I have a feeling that nothing beats a good old fashioned rain catcher reflector slung under the spreaders.

An active transponder will beat any passive reflector. Probably by an order of magnitude. To be honest I consider all passive reflectors as toys or ornaments. They might help a little (thus my suggestion of a flat pack version above), but if you actually want to be sure your radar reflector is doing anything, get a radar target enhancer (e.g. SeaMe).

 

[sailorman]

Does your anticipated usage make a radar reflector important? I would be inclined to carry a flat-pack reflector that can be slotted together, with appropriate lines so it is ready to be hoisted in the "catch rain" position and only hoist it if necessary.

If you are not sailing at night or in fog (I know it sometimes comes in unexpectedly) - why do you need a reflector at all? At least permanently mounted?

The wording is something like "one should be displayed where practicable" so i have a plastimo high up the back stay, & a firdell for fog stowed below out of the way ( no windage )

 

[Tam Lin]

Excuse my ignorance but isn't a metal mast a radar reflector?

 

[VicS]

Although now 8 years old the QinetiQ report on radar reflectors is probably still worth reading

https://assets.digital.cabinet-offi...540f0b6024400008d/Radar_reflectors_report.pdf

.

 

[VicS]

Excuse my ignorance but isn't a metal mast a radar reflector?

To some extent yes but it does not return a strong signal back to the source. The octahedral and other passive reflectors are designed to do this.

 

[prv]

Excuse my ignorance but isn't a metal mast a radar reflector?

Well, it no doubt reflects it, but not back towards the receiver . Imagine firing a stream of water from a hose at a round pole - unless you can line it up perfectly with the exact middle of the post, it's going to be directed off to one side or the other, not back at you. A radar reflector is more like hitting a snooker ball into the corner of the table - it bounces off one cushion, then off the other, then comes back on the reciprocal course (but off to one side a little).

Pete

 

[Tam Lin]

Thanks for that, you learn something new everyday!

 

[Triassic]

If it helps any I don't have a reflector mounted on my boat either. I do have one stashed away below somewhere and I guess if I were becalmed in think fog in deep water I might actually consider getting it out, but I prefer to rely on myself to stay out of trouble rather than rely on some dozy watch officer actually noticing a small blip on their screen.....

I did look into getting AIS but in my limited experience with it in the waters I mostly sail in (Thames Estuary area) it's complete information overload and it still doesn't replace the need to keep a sharp lookout. Again, most of the time I've got the speed to change course and sail away from anything I think I might be going a bit close to and if I haven't then I'll head for shallow water, which is in abundance around here!

The only time I've nearly hit anything (not including a rather embarrassing incident involving a buoy....) they have been to small to have either radar or AIS, and ignorant enough to do 20 knots in thick fog!

 

[jerrytug]

An active transponder will beat any passive reflector. Probably by an order of magnitude. To be honest I consider all passive reflectors as toys or ornaments. They might help a little (thus my suggestion of a flat pack version above), but if you actually want to be sure your radar reflector is doing anything, get a radar target enhancer (e.g. SeaMe).

+1, RTE's use a tiny amount of leccy as well, and you can of course switch them off when appropriate.

All passive reflectors have been proven to be utter gash by comparison, why not just hoist the saucepans up the flag halliard.

If you have £500 Echo Max is the one. In my humble opinion.

 

[prv]

Thanks for that, you learn something new everyday!

To be clear, a metal mast isn't going to be completely invisible to radar, same as you'd probably get a few splashes on you in the hose scenario if you were standing very close. It's just not going to be a very large target.

Pete

 

[lw395]

To be clear, a metal mast isn't going to be completely invisible to radar, same as you'd probably get a few splashes on you in the hose scenario if you were standing very close. It's just not going to be a very large target.

Pete

It's actually a pretty good target, so long as it's close to vertical.
Bigger is better of course.
A small boat like Ouzo might have a mast that is narrow compared to a wavelength, while a big boat with a fat mast is a different problem.

It helps to start with the question 'what kind of radar do I need to see me, from how far away?'.

 

[johnalison]

With my boat radar and amateur observer (me), I can usually pick up small craft at a mile or so even if they have no reflector, in good conditions. What it is like on the high seas in rain is a different matter and only an active reflector is likely to be of any real benefit. For a small boat doing coastal cruising, a collapsible octagon to be put up when necessary is what we always used and is probably the best option for those who can't justify the cost of a SeaMe. A Blipper type is a bit big to have on the mast in a small boat. My plastimo job is there to take with me in the liferaft.

 

[lw395]

.....and only an active reflector is likely to be of any real benefit.......

That's rather a sweeping statement.
If it were true, people would never have gone to the bother of mounting passive reflectors on navigation marks and so forth.

 

[st599]

To some extent yes but it does not return a strong signal back to the source. The octahedral and other passive reflectors are designed to do this.

Any conductive element is a reflector. The question is, how much is reflected back towards the radar. From a mast, not much as it is curved and moves around leading to an at best intermittent reply. You need to overcome rainscatter, waves too.

 

[lw395]

Any conductive element is a reflector. The question is, how much is reflected back towards the radar. From a mast, not much as it is curved and moves around leading to an at best intermittent reply. You need to overcome rainscatter, waves too.

That's vaguely true, but the point about radar is that it chucks out a short, very powerful pulse, e.g. a few kW.
It then receives with serious sensitivity. A few picowatts perhaps.
So 'not much' reflected can be plenty. A billionth of the transmit power will overload the receiver.

Range makes a huge difference, it is to the power 4 in the radar equation, so being seen at 3 miles needs 81 times the reflection compared to 1 mile.
So my 'nasty tubular' reflector is useful close to shore, but if I'm out in the shipping lanes in poor vis, out comes the big octahedral.
In these conditions I am happy to have a decent size one up, it would be too much drag for serious racing, that's for sure.