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Old 14 December 2007, 12:29   #11
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Commercially, we do both - the vessels have them (SOLAS requirement) and deck crews have them on lifejackets. I do the same on my own rib.

But then most people don't have that kind of cash. If one person on a boat had a personal EPIRB, and the boat didn't, it's harder to track drift etc for search patterns than the other way round. Also, what happens if you have 3 personal EPIRBS for your family, and auntie joins you for the day?

Also, the signal stregth, information burst and endurance of boat EPIRBS would give a lot more info for SAR coordinators to work on.
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Old 14 December 2007, 12:35   #12
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Makes sense, I carry radio/ mini flares personally and looking at next level for boat/crews. Have fitted large Tri Lens but like all radar refectors I have yet to find one reported as meeting all standards although each one has strengths and weaknesses
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Old 14 December 2007, 12:51   #13
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An odd thing to carry on a rib is a large roll of kitchen foil.

If you ever break down in shipping lanes, wrap the foil around the A frame as if wrapping a parcel.

Turst me, radars WILL see you. We've tried it and the results are amazing...
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Old 14 December 2007, 15:45   #14
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Quote:
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An odd thing to carry on a rib is a large roll of kitchen foil.

If you ever break down in shipping lanes, wrap the foil around the A frame as if wrapping a parcel.

Turst me, radars WILL see you. We've tried it and the results are amazing...
Have you written this experiment up at all? I recall reading about an experiment covering the bulkheads in GRP boats with foil - to the same end (but intended as a permanent fit) and it made no positive difference (to get a good return from a single flat surface it needs to be perfectly normal to the beam). I can see that there would be a difference above/below the water line. Many people will have a space blanket on board anyway so if this is reliable (i.e. visibile at all angles) it could be useful.

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Of course the best way to be seen in the first place is to fit a good radar, and have it running
do you actually mean - don't rely on someone else spotting you - spot them? or are you claiming that it is easier to spot small boats with functioning radar when on the deck of your ship - and if so can you please explain the mechanism for that?
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Old 14 December 2007, 16:02   #15
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do you actually mean - don't rely on someone else spotting you - spot them? or are you claiming that it is easier to spot small boats with functioning radar when on the deck of your ship - and if so can you please explain the mechanism for that?
Yes to both!

Of course, the best line of defence is keeping a good, 360 degree lookout - it's amazing the number of yachts who don't seem to look behind them. Never, ever rely on having been seen - doesn't matter what the ColRegs say, don't put yourself into a stand on situation if you can help it.

On the radar front, most bridge radar systems will display when they have been "painted" by a radar beam - both on S and X band. This is linked with the ARPA collision avoidance system, so yes, operating your radar will draw the attention of suitably equipped vessels to your presence.

No, we haven't written up the experiment as we didn't conduct it formally - I believe work is being done on this by other agencies buy I don't want to say who as they're doing it for purposes other than rescue!

Simon
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Old 14 December 2007, 16:43   #16
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most bridge radar systems will display when they have been "painted" by a radar beam - both on S and X band.
am I missing something but the beam is transmitted and detected from a rotating scanner - for the radar on your ship to detect the (hypothetical) radar on my boat your receiver needs to be pointing at my transmitter at exactly the moment I am transmitting. The effect of pulses must compound that - so how likely is it that your radar is pointing at mine - in "listening mode" at the exact moment (allowing for the time it takes for the radiation to travel from mine) that mine is transmitting. If my simple maths are right and the beam width is say 5 degrees - then > 98% you are not listening (in my direction) and >98% of the time I am not transmitting (in your direction). At first glance it strikes me that you have a 1:5000 chance of picking up my radar beam on your radar - and that is before I think about your radar and my radar working at different rotational speeds or pulse lengths.

Or am I being a bit thick tonight?
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Old 14 December 2007, 17:18   #17
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surely if they are working at different rotational speeds that would increase the chance of detection. If they are rotating at the same speed and not aligned the they never will be, or am I be bit thick as always
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Old 14 December 2007, 17:21   #18
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I assume they have radar detectors on board?

As to waving foil around you can get flares that release a chaff cloud - also handy if someone fires an Excocet at you.............
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Old 14 December 2007, 17:48   #19
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surely if they are working at different rotational speeds that would increase the chance of detection. If they are rotating at the same speed and not aligned the they never will be
Yes RW I think, as usual, you are correct.
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Old 14 December 2007, 18:54   #20
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Yes RW I think, as usual, you are correct.
wow.cool I take that as a compliment

BTW I think those chaff flares would be a good idea I wonder if the manufacturers have any test results from ships radars
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