Waypoint
New member
If my boat were fitted with radar and it was switched on, would my radar beam make me more visible to commercial shipping, or would I also need an active radar reflector such as a SEA-ME?
Waypoint
Waypoint
Radar Visibility
- Thread starter Waypoint
- Start date
robbieg
Active member
Need an active responder. Radar beams from your system do nothing to increase your vis as a target.
Richard10002
Well-known member
NO!
Bergman
New member
The concensus of opinion is that it will not show up another radar.
It requires an extraordinary coincidence of timing for a pulse from one radar to show up on another radar receiver. So extraordinary that it is close to impossible to occur.
It requires an extraordinary coincidence of timing for a pulse from one radar to show up on another radar receiver. So extraordinary that it is close to impossible to occur.
shmoo
New member
Would only happen once and be regarded as clutter and discarded before it reached the screen.
robbieg
Active member
Richard not sure if your disagreeing with me or answering the original post. If my comments are incorrect genuinely interested to know why.
simon_sluggett
New member
Been a lot of talk about radar reflectors lately, reports on effectiveness, ouzo.. etc. I just got a radar set and was trying it out last sunday in the solent (before the mist came down!) and was suprised how much showed up , even little fishing boats which didnt apear to have any reflectors fitted. Is it the case that reflectors give a bigger display to make ships take more notice of you. Do ships radars need a bigger reflection to set off automatic alarms.
On a slight tangent but is anyone planning to make AIS transponders more affodable to smaller vessels so ships can see what you are, before they see you. Anyone from Nasa want to take up the challange?
On a slight tangent but is anyone planning to make AIS transponders more affodable to smaller vessels so ships can see what you are, before they see you. Anyone from Nasa want to take up the challange?
Oceanmaster
New member
I believe if the Sea-Me device was half the price I would think after the Ouzo inciedent then every craft would happerly carry one even if it meant forgoing other instruments on the owners wish list.
kengill
New member
NO.
Yes.
Probably.
Yes.
Probably.
pappaecho
New member
Sea Me only works on one type of radar, which is a limitation
pvb
Well-known member
Not much of a limitation...
[ QUOTE ]
Sea Me only works on one type of radar, which is a limitation
[/ QUOTE ]The Sea-Me works on X-band, which is the most common system. If vessels have S-band installed, it will almost certainly be in addition to X-band.
[ QUOTE ]
Sea Me only works on one type of radar, which is a limitation
[/ QUOTE ]The Sea-Me works on X-band, which is the most common system. If vessels have S-band installed, it will almost certainly be in addition to X-band.
G
Guest
Guest
Re: Not much of a limitation...
That was my wonderful thought when I bought a Sea-Me. The reality is that the X-Band is not used away from busy areas. It seems the maintenance hours are an issue. There is also a direct correlation between the boats with the radar off and the ones with poor lookouts.
It also has a number of other problems. The main one is that I have found it impossible to test. Once the ship knows you are there, it seems they can see the yacht without the Sea-me switched on.
So after the lightning, I have never been able to verify it works. It also has issues with noisy power supplies like mastervolt inverters.
Sea-me is just one tool in the armoury but it is NOT the complete solution. I would not go out without a big passive reflector as well. However, I would always have one.
That was my wonderful thought when I bought a Sea-Me. The reality is that the X-Band is not used away from busy areas. It seems the maintenance hours are an issue. There is also a direct correlation between the boats with the radar off and the ones with poor lookouts.
It also has a number of other problems. The main one is that I have found it impossible to test. Once the ship knows you are there, it seems they can see the yacht without the Sea-me switched on.
So after the lightning, I have never been able to verify it works. It also has issues with noisy power supplies like mastervolt inverters.
Sea-me is just one tool in the armoury but it is NOT the complete solution. I would not go out without a big passive reflector as well. However, I would always have one.
pappaecho
New member
There is another fundamental question which I cannot answer. In 1966 /7 I worked as a student on the Portsmouth Fishbourne IOW car ferries.
When I was helming the ship I was also required to keep radar watch on a Decca Navigator radar. It switch from 2 to 32 miles in increments.
In 1966 I clearly identified a 16ft rowing boat with Sea Cadets in it at 1.5 miles at night( they were lost!)
So how come 40 years down the line we have to have radar reflectors, on much larger boats than a rowing boat with masts, and rigging which creates reflections, and with 40 years for increase in the technology.
The answer lies with the chair- screen interface. Half the time no one is looking
When I was helming the ship I was also required to keep radar watch on a Decca Navigator radar. It switch from 2 to 32 miles in increments.
In 1966 I clearly identified a 16ft rowing boat with Sea Cadets in it at 1.5 miles at night( they were lost!)
So how come 40 years down the line we have to have radar reflectors, on much larger boats than a rowing boat with masts, and rigging which creates reflections, and with 40 years for increase in the technology.
The answer lies with the chair- screen interface. Half the time no one is looking
William_H
Well-known member
I suspect many posters are confusing the radar reflection under ideal flat water conditions with those in rough water. A small boat can easily be lost in the swell as this will also reflect the radar signal. A reflector or active transponder would be a huge improvemnet under these conditions. olewill
G
Guest
Guest
pappaecho is right. It is the operation that is at fault.
He hinted at it, with the change of ranges. Each range has different pulse lengths and frequency and is therefore better for different conditions. If you read the BridgeMaster E Series manual they have an option that detects the constant echo out of the noise using 5 pulse width cell areas. The technology is all there but it is just ignored.
The expectation that small boats at 1nm range will show up on a display set to 12nm is the problem. It would be less than 0.5" from the centre blob. Which on a standard screen would be less than 30 pixels. At 1nm each pixel represents about 150m of sea area. So all the echos from the sea in that area are represented by a single dot. So there is a need for a great deal of pre-processing for a yacht to appear.
Then again they could just pop it down to 2nm range occasionally and see it all clearly.
I always wondered why radar does not have a logarithmic display mode. Then the radar could transmit short and long pulses in sequence and show all activity. OK course plotting would be harder by eye but since that is all done by ARPA what is the problem. You could switch back to linear distance easily. Or why not have two displays off one head unit and interleave the pulses. All perfectly possible but the "will" to see the small boat is not present.
How come they see buoys?
He hinted at it, with the change of ranges. Each range has different pulse lengths and frequency and is therefore better for different conditions. If you read the BridgeMaster E Series manual they have an option that detects the constant echo out of the noise using 5 pulse width cell areas. The technology is all there but it is just ignored.
The expectation that small boats at 1nm range will show up on a display set to 12nm is the problem. It would be less than 0.5" from the centre blob. Which on a standard screen would be less than 30 pixels. At 1nm each pixel represents about 150m of sea area. So all the echos from the sea in that area are represented by a single dot. So there is a need for a great deal of pre-processing for a yacht to appear.
Then again they could just pop it down to 2nm range occasionally and see it all clearly.
I always wondered why radar does not have a logarithmic display mode. Then the radar could transmit short and long pulses in sequence and show all activity. OK course plotting would be harder by eye but since that is all done by ARPA what is the problem. You could switch back to linear distance easily. Or why not have two displays off one head unit and interleave the pulses. All perfectly possible but the "will" to see the small boat is not present.
How come they see buoys?
boatmike
Well-known member
Agree it would be an improvement olewill. Huge... well I don't know... but I am surprised at all the questions. Anyone who has radar on their own boat and has seen the miniscule returns from other yachts, mostly carrying reflectors, knows how poorly a very curvy shape made out of plastic shows up! I got a superb return from a yacht last year and when he came in to Cherbourg saw why. Big steel flat sided thing with a square box on top for a wheelhouse. Looked terrible but didn't half show up on my radar!
duncan
Active member
funnily enough I had a fair bit of use of mine last weekend in the CIs given the fog......only a basic JRC1500 and Mki too - but providing I reset the gain when changing the range it showed up the curved plastic things just as well as the rocky bits, the metal bits and the bloody big bits. Only really nice 'show' was the racon at casquettes though.......very usefull.
but yes very calm conditions
but yes very calm conditions
dulcibella
Active member
Even a cheap radar shows gulls on a flat sea - it all depends on the sea state.