Piers
Well-Known Member
I can never remember - is marine leisure radar S or X band?
S or X band?
- Thread starter Piers
- Start date
peterb
Well-Known Member
X
S
Skyva_2
Guest
S is for 'Ships', is one way to remember it.
Piers
Well-Known Member
Thank you
Dyflin
Well-Known Member
I find it easier to call it 3cm or 10cm, makes a bit more sense to me.
Piers
Well-Known Member
So is X band 3 cm and S band 10 cm?
Refueler
Well-Known Member
[ QUOTE ]
I find it easier to call it 3cm or 10cm, makes a bit more sense to me.
[/ QUOTE ]
Exactly.
3cm is better definition for navigational purposes and also picks up smaller targets, but suffers worst for sea-state / rain etc.
10cm - was always the USA preference and is better in poor conditions, but loses definition compared to 3cm.
It's well to note that not all RACON's or radar re-transmitters can handle both 3 & 10 ... many are 3cm only - well thats how it used to be.
I find it easier to call it 3cm or 10cm, makes a bit more sense to me.
[/ QUOTE ]
Exactly.
3cm is better definition for navigational purposes and also picks up smaller targets, but suffers worst for sea-state / rain etc.
10cm - was always the USA preference and is better in poor conditions, but loses definition compared to 3cm.
It's well to note that not all RACON's or radar re-transmitters can handle both 3 & 10 ... many are 3cm only - well thats how it used to be.
Refueler
Well-Known Member
X = 3cm and needs normally for long 'cable' runs a waveguide channel not cable.
S = 10cm and is happy along heavy duty cable.
S = 10cm and is happy along heavy duty cable.
johnphilip
Well-Known Member
The Sea-Me active radar reflector is meant to be hugely more effective than normal reflectors, but it only responds to X band. Does this compromise its effectiveness or do ships normally monitor both?
Piers
Well-Known Member
There are two main issues here. Leisure yachts use X band so a Sea-Me should show up well. Good news so far. Ships use both X and S band radars, so should see you on their X band receiver. Good news continues.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
However, I believe the Sea-Me gives the best possbile return in comparison with any non-active reflector.
I use a Sea-Me and wouldn't change it for anything. I have done unofficial trials with MBM on the product which shows the return is a slightly larger than normal, but it's a strong solid blip on the screen - you can't miss it.
Distance-wise, it's great to about 4 miles, then starts to fade away, although this will depened upon the receiving radar antennae height.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
However, I believe the Sea-Me gives the best possbile return in comparison with any non-active reflector.
I use a Sea-Me and wouldn't change it for anything. I have done unofficial trials with MBM on the product which shows the return is a slightly larger than normal, but it's a strong solid blip on the screen - you can't miss it.
Distance-wise, it's great to about 4 miles, then starts to fade away, although this will depened upon the receiving radar antennae height.
earlybird
Well-Known Member
[ QUOTE ]
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
[/quote.
Why would a ship use the longer wavelength system, with it's inherenly poorer definition, for close quarters? I would have expected the reverse.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
[/quote.
Why would a ship use the longer wavelength system, with it's inherenly poorer definition, for close quarters? I would have expected the reverse.
pvb
Well-Known Member
[ QUOTE ]
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
[/quote.
Why would a ship use the longer wavelength system, with it's inherenly poorer definition, for close quarters? I would have expected the reverse.
[/ QUOTE ]And you'd be right. Ships use X-band close to shore, but use S-band offshore, where its greater range and reduced interference from rain and sea clutter is a benefit.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
[/quote.
Why would a ship use the longer wavelength system, with it's inherenly poorer definition, for close quarters? I would have expected the reverse.
[/ QUOTE ]And you'd be right. Ships use X-band close to shore, but use S-band offshore, where its greater range and reduced interference from rain and sea clutter is a benefit.
Piers
Well-Known Member
So is there a chance a ship would only be using an S band radar and therefore be likely not to get a Sea-Me return?
pvb
Well-Known Member
Offshore, it's likely that ships will rely primarily on S-band, and may not have X-band working. In those circumstances, a Sea-Me may not be any great benefit.
Refueler
Well-Known Member
[ QUOTE ]
There are two main issues here. Leisure yachts use X band so a Sea-Me should show up well. Good news so far. Ships use both X and S band radars, so should see you on their X band receiver. Good news continues.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
However, I believe the Sea-Me gives the best possbile return in comparison with any non-active reflector.
I use a Sea-Me and wouldn't change it for anything. I have done unofficial trials with MBM on the product which shows the return is a slightly larger than normal, but it's a strong solid blip on the screen - you can't miss it.
Distance-wise, it's great to about 4 miles, then starts to fade away, although this will depened upon the receiving radar antennae height.
[/ QUOTE ]
I don't know about ships generally now except talking to officers when on-board as part of my work. But in my days on the bridge 3cm radar was preferred unit for its better definition of target such as land etc.
Piers you mention that a ship would use 10cm for close 1/4's such as in ahrbour .... unless a unit is faulty - BOTH units - actually ALL radars will be operating for sheer safety reasons. On many ships nowadays that will be 3 radars or at least a minimum of 2. The preferred would also be 3cm for reasons I have already given.
Example of definition and use of. Palawan Passage en route Brunei to / from Japan. Liner gas ships with Shell. We had 3cm and 10cm units installed on bridge. They were interfaced with a change over unit that could swap scanners to which unit we preferred. The 3cm was always linked to the scanner on the side that was to landward. It was my job on one of those vessels to swap over at start of the trip and tune up ready for start of passage.
There are two main issues here. Leisure yachts use X band so a Sea-Me should show up well. Good news so far. Ships use both X and S band radars, so should see you on their X band receiver. Good news continues.
The only draw back is if a ship is not using its X band radar and therefore will not see the Sea-Me return. Althought possible, I am advised this is unlikely since S band is mainly used for close quarters manoeuvering such as in harbour.
However, I believe the Sea-Me gives the best possbile return in comparison with any non-active reflector.
I use a Sea-Me and wouldn't change it for anything. I have done unofficial trials with MBM on the product which shows the return is a slightly larger than normal, but it's a strong solid blip on the screen - you can't miss it.
Distance-wise, it's great to about 4 miles, then starts to fade away, although this will depened upon the receiving radar antennae height.
[/ QUOTE ]
I don't know about ships generally now except talking to officers when on-board as part of my work. But in my days on the bridge 3cm radar was preferred unit for its better definition of target such as land etc.
Piers you mention that a ship would use 10cm for close 1/4's such as in ahrbour .... unless a unit is faulty - BOTH units - actually ALL radars will be operating for sheer safety reasons. On many ships nowadays that will be 3 radars or at least a minimum of 2. The preferred would also be 3cm for reasons I have already given.
Example of definition and use of. Palawan Passage en route Brunei to / from Japan. Liner gas ships with Shell. We had 3cm and 10cm units installed on bridge. They were interfaced with a change over unit that could swap scanners to which unit we preferred. The 3cm was always linked to the scanner on the side that was to landward. It was my job on one of those vessels to swap over at start of the trip and tune up ready for start of passage.
Piers
Well-Known Member
So are we saying that a Sea-Me should also respond to S band to ensure visibility?
Refueler
Well-Known Member
[ QUOTE ]
So is there a chance a ship would only be using an S band radar and therefore be likely not to get a Sea-Me return?
[/ QUOTE ]
I acn again only reply based on my years at sea some time ago - we used 3cm usually, as most UK reg'd ships were fitted with primary unit as a 3cm. 10cm was installed as secondary and was often joked as our American Friend ! Whether true or not, it was said then that 10cm was US preference.
I know I shouldn't say this - but I sailed with a few masters who insisted that radars were switched off once 50miles offshore. A few others would insist only 3cm was used unless increased watch required and then only 10cm could be switched on as well. Luckily those Dinosaurs have retired and moved on to commanding Bathchairs. (Actually the reason was that Magnetrons etc. had limited life and they were remembering early days of radar ....)
Funny story .... a certain Oil Co' had ships in nearly every part of the world and only the new builds were coming out with radar ... we are talking many years ago.
Anyway there was a fleet of older smaller regulars in Singapore without radar.
It's said the one day one of the new ships was sitting at anchor at Eastern Quarantine and one of the old small regulars steamed out into the straits past her.
Captain was called to bridge to witness this old tub proudly displaying a rotating radar scanner on top of wheelhouse. A quick telegram was rushed of to Local Office in Singapore demanding to know why such an old boat was so equipped.
Story goes that crew on old tub decided to install their own DIY broom-handle and mock scanner up through deck ........ /forums/images/graemlins/wink.gif
So is there a chance a ship would only be using an S band radar and therefore be likely not to get a Sea-Me return?
[/ QUOTE ]
I acn again only reply based on my years at sea some time ago - we used 3cm usually, as most UK reg'd ships were fitted with primary unit as a 3cm. 10cm was installed as secondary and was often joked as our American Friend ! Whether true or not, it was said then that 10cm was US preference.
I know I shouldn't say this - but I sailed with a few masters who insisted that radars were switched off once 50miles offshore. A few others would insist only 3cm was used unless increased watch required and then only 10cm could be switched on as well. Luckily those Dinosaurs have retired and moved on to commanding Bathchairs. (Actually the reason was that Magnetrons etc. had limited life and they were remembering early days of radar ....)
Funny story .... a certain Oil Co' had ships in nearly every part of the world and only the new builds were coming out with radar ... we are talking many years ago.
Anyway there was a fleet of older smaller regulars in Singapore without radar.
It's said the one day one of the new ships was sitting at anchor at Eastern Quarantine and one of the old small regulars steamed out into the straits past her.
Captain was called to bridge to witness this old tub proudly displaying a rotating radar scanner on top of wheelhouse. A quick telegram was rushed of to Local Office in Singapore demanding to know why such an old boat was so equipped.
Story goes that crew on old tub decided to install their own DIY broom-handle and mock scanner up through deck ........ /forums/images/graemlins/wink.gif
Piers
Well-Known Member
I've asked Peter Munro (who makes the Sea-Me) if he has plans to make it respond to both bands. I'll let you know what he says.
Piers
Well-Known Member
I am advised ther will be a dual band Sea-Me as soon as the authorities have issued the new spec which the IMO is changing. Might be available 1st or 2nd qtr 2009., although deadlines keep changing.
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