boatmike
Well-Known Member
Anyone know where I can buy some of those neat little stainless steel mounting brackets to fix a Firdell Blipper radar reflector to the front of my mast?
Firdell Blipper Mounting Brackets
- Thread starter boatmike
- Start date
AIDY
Well-Known Member
Some in marine superstore Port solent last weekend.
Talulah
Well-Known Member
Bought a pair a week ago from Ocean Leisure in London. They were in their clear out box. (Paid £5) Don't know if they have any more but I may be passing by this evening.
Normally these are some ridiculous price £20 - £30.
Having seen these I would recommend buying some aluminium sheet from B&Q and making them yourself.
Also, the Firdell Blipper radar reflector fails most of the tests. i.e Not sufficient for coding/RORC requirements. Echomax does pass but is slightly bigger.
Normally these are some ridiculous price £20 - £30.
Having seen these I would recommend buying some aluminium sheet from B&Q and making them yourself.
Also, the Firdell Blipper radar reflector fails most of the tests. i.e Not sufficient for coding/RORC requirements. Echomax does pass but is slightly bigger.
jerryat
Well-Known Member
Yep, I agree. I knocked mine out of a couple of bits of gash stainless steel sheet 'cos I refused to pay the extortionate price charged for the 'real' thing.
Some corrosion resistant paste, pop rivets and job done. Cost next to nothing!
Some corrosion resistant paste, pop rivets and job done. Cost next to nothing!
srm
Well-Known Member
They might be neat and tidy but dont expect anyone to see you on their radar from astern or on either quarter. Exact geometry depends on the size and section of your mast but basically an alloy mast deflects the incomming and / or outgoing radar pulse so that they do not return to the scanner and no response is received from your reflector.
For best results mount the Blipper (or any other reflector) as far away from your mast as possible, a halyard on the backstay is the best most of us can manage. This reduces the shadow and blind sectors produced by the mast.
If you want a radar reflector to work make sure there is a clear 'line of sight' between it and the radar scanner.
For best results mount the Blipper (or any other reflector) as far away from your mast as possible, a halyard on the backstay is the best most of us can manage. This reduces the shadow and blind sectors produced by the mast.
If you want a radar reflector to work make sure there is a clear 'line of sight' between it and the radar scanner.
michael_w
Well-Known Member
[ QUOTE ]
They might be neat and tidy but dont expect anyone to see you on their radar from astern or on either quarter. Exact geometry depends on the size and section of your mast but basically an alloy mast deflects the incomming and / or outgoing radar pulse so that they do not return to the scanner and no response is received from your reflector.
[/ QUOTE ]
Probably true if the boat stays perfectly still. I've always found they move about a bit. /forums/images/graemlins/grin.gif
They might be neat and tidy but dont expect anyone to see you on their radar from astern or on either quarter. Exact geometry depends on the size and section of your mast but basically an alloy mast deflects the incomming and / or outgoing radar pulse so that they do not return to the scanner and no response is received from your reflector.
[/ QUOTE ]
Probably true if the boat stays perfectly still. I've always found they move about a bit. /forums/images/graemlins/grin.gif
jerryat
Well-Known Member
Hi srm,
Blimey, I've long since ceased to worry about whether I can be seen or not!! One can only do a certain amount, and the Blipper (or Furneaux as I actually have) type are as good as any.
It's better than nothing and I have no intention of being persuaded down the electronic 'positive return' route, or whatever it's called.
Blimey, I've long since ceased to worry about whether I can be seen or not!! One can only do a certain amount, and the Blipper (or Furneaux as I actually have) type are as good as any.
It's better than nothing and I have no intention of being persuaded down the electronic 'positive return' route, or whatever it's called.
Gin
Well-Known Member
£36 a pair actually
Whew!!!
Whew!!!
neale
Well-Known Member
There's a pair on ebay right now. £10 starting price and no bids.
boatmike
Well-Known Member
Interesting Talulah. If you see any more when passing I publicly promise its worth a bottle of wine! I see you are in Gosport sometimes. I am in Lee-on -Solent so if it were possible I would be most grateful.....
As far as performance is concerned, it's an interesting and complex subject. When working for a certain south coast shipbuilder building landing craft, we performed some trials involving Marconi (as they then were) . The conclusion was that nothing size for size beat the good old octohedron mounted properly in the "rain catch" position. Compared with other passive reflectors the blipper did quite well though. The Echomax probably does better because it is bigger. The conclusion was that the marines chose the blipper for performance and convenience of hoisting and lowering. Very often for obvious reasons a landing craft does not want to be seen on radar! The octohedron is awkward to deploy/retrieve in a hurry.
My own plan (like many others) is to have the blipper permanently mounted all of the time. In bad viz or in shipping channels I will hoist an octohedron at the radar arch at the stern. As it's a catamaran the known tendancy of the blipper to "dissapear" when heeled (it's main failing we found) is also less of a problem.
As far as performance is concerned, it's an interesting and complex subject. When working for a certain south coast shipbuilder building landing craft, we performed some trials involving Marconi (as they then were) . The conclusion was that nothing size for size beat the good old octohedron mounted properly in the "rain catch" position. Compared with other passive reflectors the blipper did quite well though. The Echomax probably does better because it is bigger. The conclusion was that the marines chose the blipper for performance and convenience of hoisting and lowering. Very often for obvious reasons a landing craft does not want to be seen on radar! The octohedron is awkward to deploy/retrieve in a hurry.
My own plan (like many others) is to have the blipper permanently mounted all of the time. In bad viz or in shipping channels I will hoist an octohedron at the radar arch at the stern. As it's a catamaran the known tendancy of the blipper to "dissapear" when heeled (it's main failing we found) is also less of a problem.
boatmike
Well-Known Member
At that price I would indeed make my own. That is a rip off.
boatmike
Well-Known Member
Far be it from me to wish to dissagree with a fellow Prout owner but your post puts the popularly understood version of what sounds like solid common sense but it aint quite like that!
I am not an expert but have been involved in trials of the things and some really peculiar things happen. One of the WORST things you can do is mount the reflector about 1/2 metre away from the mast. I can't tell you why but when we did this from a certain angle the boat dissapeared entirely. Lower the radar reflector and it re-appeared! Yes I DO mean the boat was WORSE with a radar reflector than without..... I seem to remember that PBO or Yachting Monthly a couple of years back did a test that confirmed the same thing. Hoisting from the crosstrees therefore is not a good idea, but that's where you often see them.... If you have a radar yourself you will know that many yachts have a pathetic signature. Some don't. It's very interesting (and sobering) to see your own boat on someone elses radar.....
What you think SHOULD work often doesn't. A blipper mounted on the front of the mast gives a quite reasonable signature on most boats from every direction apart from dead aft. as I have said elsewhere my solution to this is to hoist the good old octohedron at the stern when in shipping lanes or bad vis. but even here there is a problem as two of the little b*****s can cancel one another out... Solution to this seems to be if you have two don't mount them at the same height. Whatever you do it's a good idea to ask your mate to look on his radar to see if he can see you and vice versa. Proof of the pudding and all that.....
I am not an expert but have been involved in trials of the things and some really peculiar things happen. One of the WORST things you can do is mount the reflector about 1/2 metre away from the mast. I can't tell you why but when we did this from a certain angle the boat dissapeared entirely. Lower the radar reflector and it re-appeared! Yes I DO mean the boat was WORSE with a radar reflector than without..... I seem to remember that PBO or Yachting Monthly a couple of years back did a test that confirmed the same thing. Hoisting from the crosstrees therefore is not a good idea, but that's where you often see them.... If you have a radar yourself you will know that many yachts have a pathetic signature. Some don't. It's very interesting (and sobering) to see your own boat on someone elses radar.....
What you think SHOULD work often doesn't. A blipper mounted on the front of the mast gives a quite reasonable signature on most boats from every direction apart from dead aft. as I have said elsewhere my solution to this is to hoist the good old octohedron at the stern when in shipping lanes or bad vis. but even here there is a problem as two of the little b*****s can cancel one another out... Solution to this seems to be if you have two don't mount them at the same height. Whatever you do it's a good idea to ask your mate to look on his radar to see if he can see you and vice versa. Proof of the pudding and all that.....
boatmike
Well-Known Member
Yeah but he sails a Prout you see..... They don't.....
srm
Well-Known Member
I am basing my comments on inefective mast mounted radar reflectors on practical experienced based on both monohulls and catamarans, as well as being a lecturer running MCA approved radar and electronic navigation courses.
I am not too keen on using an active transponder, so have a blipper mounted on the front of the mast, it came with the boat, and my well proven and somewhat larger Firdel Pentland reflector mounted on the stern.
I would also point out that having sailed most of the way around Britain over two summers most yachts were invisible on my 2Kw Raymarine radar until within 2 miles, some only showing at less than 1 mile.
Boatmikes experience may well be due to phase cancellation of the radar pulse, where a direct and reflected signal arive at the scanner near enough 180 degrees out of phase. This can be due to the pulse bouncing off a calm sea surface or another reflecting surface.
I am not too keen on using an active transponder, so have a blipper mounted on the front of the mast, it came with the boat, and my well proven and somewhat larger Firdel Pentland reflector mounted on the stern.
I would also point out that having sailed most of the way around Britain over two summers most yachts were invisible on my 2Kw Raymarine radar until within 2 miles, some only showing at less than 1 mile.
Boatmikes experience may well be due to phase cancellation of the radar pulse, where a direct and reflected signal arive at the scanner near enough 180 degrees out of phase. This can be due to the pulse bouncing off a calm sea surface or another reflecting surface.
boatmike
Well-Known Member
I don't disagree with what you say. My only point is it's a more complex subject than your original post indicated. I certainly agree that most yachts (possibly because of their shape and materials of construction) are very poor radar reflectors and are only visible at a 2 or three mile range at best with or without a reflector The power of the T/R set used, and the height of the antennea will have some effect so if you are visible from 2 miles from another yacht with only 2KW at a modest height you might well be visible at 3-5 miles from a Ship. However all we can do is ensure we do the best we can to improve our signature and there are very few places on a yacht where a permanent reflector can be mounted without causing a problem so I still say a blipper or similar on the mast is better than nothing at all. A more effective but possibly temporary hoisting of a secondary reflector aft is a good idea too. The aft mount overcomes the objection you rightly make to mast shadow as well. I see that we end up actually doing the same thing in practice the only difference being that you use a Pentland and I prefer to rely on the older but very well proven octohedron which I still believe is hard to beat, especially on a cat where is stays the right way up.
What often surprises me is that while everybody and his brother seems to want a radio check every five minutes, very few skippers seem to call one another up to ask "can you see me on radar?" It's a good idea to check as I said. Proof of pudding etc.etc. I would certainly check this if like you and I we choose to hoist two reflectors. Through experiment I know that my set up gives a good return of signal from about 3 miles and an intermittent one up to 4-5 from another yacht. I dont think you can do too much better than this.
Have you checked your own?
What often surprises me is that while everybody and his brother seems to want a radio check every five minutes, very few skippers seem to call one another up to ask "can you see me on radar?" It's a good idea to check as I said. Proof of pudding etc.etc. I would certainly check this if like you and I we choose to hoist two reflectors. Through experiment I know that my set up gives a good return of signal from about 3 miles and an intermittent one up to 4-5 from another yacht. I dont think you can do too much better than this.
Have you checked your own?
jerryat
Well-Known Member
Hi Mike!
Your point -- " What often surprises me is that while everybody and his brother seems to want a radio check every five minutes, very few skippers seem to call one another up to ask "can you see me on radar?" -- is what has led, in part, to my attitude and is one of the reasons for my earlier comment - "Blimey, I've long since ceased to worry about whether I can be seen or not!!
Several times over the years on long passages, we've called up a ship to ask precisely that. On only ONE occasion did they have their radar turned on! They were delighted to break up the boredom of their watch for a chat, which prompted us to wonder why, if there was someone on watch, why not use the radar?
Perhaps, there is an alarm or something when a call on 16 is received, and the watchkeeper jumps off his berth and rushes to answer it!! /forums/images/graemlins/smile.gif All of these call-ups have been miles out into the Atlantic, but even so, we couldn't understand why, with all the power ships have available, running a radar wouldn't be done.
It's different for yachts with their meagre power supplies, but ships ............ /forums/images/graemlins/frown.gif
I appreciate you refer to other yachts, but it's the big 'uns that are of more concern to me and I'm not sure that info from a yacht (experience, competence, tuning etc spring to mind) would be of huge benefit.
Your point -- " What often surprises me is that while everybody and his brother seems to want a radio check every five minutes, very few skippers seem to call one another up to ask "can you see me on radar?" -- is what has led, in part, to my attitude and is one of the reasons for my earlier comment - "Blimey, I've long since ceased to worry about whether I can be seen or not!!
Several times over the years on long passages, we've called up a ship to ask precisely that. On only ONE occasion did they have their radar turned on! They were delighted to break up the boredom of their watch for a chat, which prompted us to wonder why, if there was someone on watch, why not use the radar?
Perhaps, there is an alarm or something when a call on 16 is received, and the watchkeeper jumps off his berth and rushes to answer it!! /forums/images/graemlins/smile.gif All of these call-ups have been miles out into the Atlantic, but even so, we couldn't understand why, with all the power ships have available, running a radar wouldn't be done.
It's different for yachts with their meagre power supplies, but ships ............ /forums/images/graemlins/frown.gif
I appreciate you refer to other yachts, but it's the big 'uns that are of more concern to me and I'm not sure that info from a yacht (experience, competence, tuning etc spring to mind) would be of huge benefit.
srm
Well-Known Member
Last summer over 2 weeks in the North Sea I monitored CPAs of commercial ships. Most were at exactly 1 mile which implies that they had aquired my vessel as a consistent target at sufficient range to make a trial manouvre on Arpa and then make the alteration. In practice this would be done at around 3 - 4 miles.
As always there was a joker. This one was overtaking on a murky night and eventually passed with a CPA of less than 0.25 mile. But then he had shown no indication of noticing a spotlight aimed at his bridge at ranges of 1.5 mile, 1.0 mile and 0.5 mile so the problem was more likely the lack of human awareness rather than electronic.
As always there was a joker. This one was overtaking on a murky night and eventually passed with a CPA of less than 0.25 mile. But then he had shown no indication of noticing a spotlight aimed at his bridge at ranges of 1.5 mile, 1.0 mile and 0.5 mile so the problem was more likely the lack of human awareness rather than electronic.