geoid96
Well-Known Member
Range isn't a black and white thing. Max range is not the issue, however a return at 20 miles indicates a strong return at 5 miles where it will be a benefit.
Active Radar Reflector - My recent experience
- Thread starter Scotty_Tradewind
- Start date
Range isn't a black and white thing. Max range is not the issue, however a return at 20 miles indicates a strong return at 5 miles where it will be a benefit.
john_morris_uk
Well-Known Member
The difference is that ships use MARPA and every one of them has a big radar screen, so it's good that they can see you.
Most yachts don't have MARPA, so they want to use AIS to keep clear of ships and use the inbuilt software for CPAs and TCPAs - all of which is knackered by class B AIS transponders.
Ships rarely have AIS display screens, just three line text readouts of AIS positions - usefulThis used to be true but hasn't been the case for several years.
So using active RADAR means everyone sees you, use class B AIS transponders and pretty much only yachts see you and you screw up their alarms. Ho hum.
May I ask what evidence you have to make these claims? The last one in particular is complete bunkum.
PS I often sail yachts that have a form of MARPA on their Radar. (And by the way MARPA is the term normally used for yacht radar target tracking: big ships use ARPA) AIS integrated onto the display can be very helpful, but AIS is another subject.
Well described and IMHO this is a good explanation.
Conachair
Guest
My steel boat gets picked up a long way away by the big boys. From watching them on AIS offshore I know they start any avoiding action way before they appear over the horizon, 5 miles away and it's already been done. A 20 mile return has benifits from being seen by the boats you want to be seen by.
john_morris_uk
Well-Known Member
Quite! What you don't want to happen is to be a variable and unreliable radar return at five or six miles which is when many ships start thinking about what they are going to do.
ghostlymoron
Well-Known Member
agree interesting OP and i also agree it's good to be visible. The reason to turn off is surely to save power. I don't know how power hunger active reflectors are.
sailorman
Well-Known Member
maxi77
Well-Known Member
Is that Swans the boats or swans the birds, if the latter and they have active transponders then evolution has stepped up a gear
We have a Sea Me, only switched it on once last year to check that it is working - it is there for murky conditions in the Thames and the Channel. Leaving it switched on in clear conditions seems of little value.
It was the birdy kind and the only explanation we could come up with was that the birds sculls were just the right size to give an enhanced return, it was a very weird experience. Still the main point is unexplained returns can be very distracting, as a warship with 'specials' closed up we had plenty of people to cope with the unexpected, but a single man on a merchant ship bridge is very different
Leif-J
Well-Known Member
Am surprised nobody mentioned the (for me at least) most important effect of an active radar reflector: It will warn me well in advance when someone is closing in on me. This is especially (or perhaps only) important when sailing off shore short handed.
At this stage I do not have an Echomax, but it is on my list to fit one before we set out long(er) distance sailing.
At this stage I do not have an Echomax, but it is on my list to fit one before we set out long(er) distance sailing.
maxi77
Well-Known Member
It will warn you about some one with radar operating, just as AIS will warn you of some one with AIS. At the end of the day there is no substitute for a good lookout.
Pinnacle
Well-Known Member
Currently in the process of installing a transponder. I too will have a switch so that on a "bright summer's day in the Solent" it will not be transmitting.
oldvarnish
Well-Known Member
I've had a Radar Enhancer for over ten years now. I am CONVINCED that in open and unrestricted waters ships take avoiding action (if necessary) far earlier than I ever remember them doing before.
Said it before, but a combination of a Radar Enhancer and a good AIS with a proper display is the greatest contribution to small craft safety; far ahead of radar which requires considerable skill to operate and assess and takes your attention from where it should be, which is in the cockpit with a good pair of binoculars and a mug of tea.
Said it before, but a combination of a Radar Enhancer and a good AIS with a proper display is the greatest contribution to small craft safety; far ahead of radar which requires considerable skill to operate and assess and takes your attention from where it should be, which is in the cockpit with a good pair of binoculars and a mug of tea.
AntarcticPilot
Well-Known Member
I've got a SeaMe, and think it is a valuable addition to the safety equipment on-board, far better than a passive reflector, and it is great to get confirmation that it really does work!
However, there is one technical issue that I'd be interested if anyone knows more!
Radar operates by timing the interval between transmit and receipt of a pulse. A Radar transponder works by receiving the pulse and then transmitting a more powerful copy of it. This necessarily introduces a (tiny) delay that a direct reflection would not have.
The question is, does anyone know how big the delay is? This will, of course, translate into the echo being plotted a little further away from the radar-equipped vessel than it should. meaning that CPA and so forth computed by ARPA in the radar will be off by a similar amount.
I doubt whether it is a serious issue; no doubt the manufacturers have done what thay can to minimize this effect! But given that some radar users seem to regard CPAs of cables as being acceptable, it would be nice to know how big an effect it is.
However, there is one technical issue that I'd be interested if anyone knows more!
Radar operates by timing the interval between transmit and receipt of a pulse. A Radar transponder works by receiving the pulse and then transmitting a more powerful copy of it. This necessarily introduces a (tiny) delay that a direct reflection would not have.
The question is, does anyone know how big the delay is? This will, of course, translate into the echo being plotted a little further away from the radar-equipped vessel than it should. meaning that CPA and so forth computed by ARPA in the radar will be off by a similar amount.
I doubt whether it is a serious issue; no doubt the manufacturers have done what thay can to minimize this effect! But given that some radar users seem to regard CPAs of cables as being acceptable, it would be nice to know how big an effect it is.
Georgio
Well-Known Member
I fitted an Echomax XS when it was first launched and having used is a couple of years I would not be without it.
I would never bother having it on in the Solent but I have used it both offshore and for channel crossings where it has prooved to be effective at both making me visable and also warning me of large ships when they are still over the horizon.
If you are planing to sail offshore single or short handed I believe that this and an AIS transponder are extreemly usefull bits of kit.
I would never bother having it on in the Solent but I have used it both offshore and for channel crossings where it has prooved to be effective at both making me visable and also warning me of large ships when they are still over the horizon.
If you are planing to sail offshore single or short handed I believe that this and an AIS transponder are extreemly usefull bits of kit.
sailorman
Well-Known Member
on a cross channel passage why do you need to know what's over the horizon
prv
Well-Known Member
lw395
Well-Known Member
The Echomax website says the position accuracy of the enhanced return is better than a metre.
So I think they must rely on isolation between receive and transmit antennas.
That seems consistent with the antenna pattern they imply from the heeled performance data.
Note that by 20 degrees of heel the performance is a very long way down on vertical.
I suspect that there is a null not far from 25 degrees of heel?
That would only be an issue if the radar was abeam of you.
sailorman
Well-Known Member
i dont see that. you dont need to know a ship is 10 mls away
Georgio
Well-Known Member
It's handy if you are single handed and cooking/navigating/snoozing below. I don't really deem x-channel as offshore sailing as you are generally not going to be more than 6hrs from port in a reasonable sized boat.
All these tools really come into their own when you have been beating to windward for 3 or 4 days, you are in need of sleep and single/short handed.
Georgio
Well-Known Member
In my view it is never too early to know that there is a danger nearby, especially if you are deaing with other things at the time (cooking/changing headsail, etc).
geoid96
Well-Known Member
You are doing 6 knots; the ship is doing 20 knots. That's a TCPA of not much more than 20 minutes. In open water I would certainly like to be aware and able to plan that far ahead.
