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Old 03-08-2013, 20:44   #721
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pirate Re: Schooner Nina - MERGED 3 THREADS

Quote:
Originally Posted by goboatingnow View Post
Everything has a failure rate. That doesn't invalidate its purpose.

With the greatest respect to all involved , this is now, most unlikely to be an " overdue " boat. Sustaining several lives with little water , or food for 2 months in winter in an area known for bad weather. Well , what are the odds.

The sea remains all powerful.

Dave
Did Bligh not have 12 or more in a smaller open boat... just saying...
And as for EPIRB's.... there's big holes in the coverage... doubt if its advertised but then... 50/50 with is no worse than 50/50 without
It may be all powerful... but only if you fight it...
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Old 03-08-2013, 20:46   #722
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Re: Schooner Nina - MERGED 3 THREADS

Interesting link...

Beacon Testing and Certification | Mainstay Marine


All Distress beacons have a "SELF TEST " function but exactly what does this test? When the self test is activated the Beacon sends an inverted signal to the satellite. This signal is then sent to the ground station and Ignored. Test complete!! What we have absolutely no way of knowing is :
  • Was the signal even sent?
  • Was the signal received?
  • Was the signal coded correctly?
  • Does the GPS component work correctly?
  • Did I just use the last of my battery?
  • Did anything happen at all or was it just that the test light illuminated ?
In simplistic terms the test switch on Epirb's and PLB's performs a very similar test to picking up the microphone on your radio.... Keying the transmit key.... Observing a transmit indication on the radio.... and then concluding that the radio is operating 100% correct. Would you set sail or leave for your outdoor adventure with only that level of radio testing???
Some of the later developments in Beacon Manufacture incorporate some more advanced technology which give some assurances once activated. For example the AquaLink™ 406, the AquaLink View™ adds a reassuring element with its next-generation digital display. Upon activation, the high-visibility screen displays a continuous stream of crucial data, including:
• Confirmation that the beacon is working
• Your exact GPS coordinates
• Remaining battery power
With some Beacon models when In self-test mode, the screen reports status of the 406 MHz signal, GPS acquisition and battery power, and provides notification of required actions, such as "Send for Service.”
Even this is information is not telling you that the EPIRB is operating 100%.
The only way to be assured that a Distress Beacon is working correctly is to have it tested in a Live Transmit situation.
In all fairness to the manufactures of Distress Beacons these devices normally operate with great success and are credited with saving many lives.
For most commercial applications it is mandatory for Annual and sometimes monthly inspection and testing. Read the I.M.O.........GUIDELINES ON ANNUAL TESTING OF 406 MHZ SATELLITE EPIRBs and GUIDELINES FOR SHORE-BASED MAINTENANCE OF SATELLITE EPIRBs
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Old 03-08-2013, 20:48   #723
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Re: Schooner Nina - MERGED 3 THREADS

On a side note, I found an old copy of "best of yachting" published maybe around 1980. Has excerpts of 3 articles featuring Nina. Most interesting was how old she was considered in 1962 when she won the Bermuda race.

I guess this thread will just go on and on?
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Old 03-08-2013, 20:50   #724
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pirate Re: Schooner Nina - MERGED 3 THREADS

Oh... and the survivors of that disastrous Antarctic expedition that made it to the Falklands... also an open boat...
Strange things happen at sea....
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Old 03-08-2013, 20:51   #725
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Re: Schooner Nina - MERGED 3 THREADS

Goboatingnow. Thanks for your input. It is interesting that you say that there are many factors that can prevent EPIRB detection. Please expand on this?

Although the manner in which an EPIRB failed to work would be interesting, it would be enough for me to know the number of vessels that are fitted with EPIRBS and fail to complete a distress call that is recognised by the ground station and the number of received distress calls. It really doesn't matter if these figures are global or per area, provided I know the what the collection method is.
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Old 03-08-2013, 20:55   #726
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Re: Schooner Nina - MERGED 3 THREADS

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Originally Posted by boatman61 View Post
Did Bligh not have 12 or more in a smaller open boat... just saying...
And as for EPIRB's.... there's big holes in the coverage... doubt if its advertised but then... 50/50 with is no worse than 50/50 without
It may be all powerful... but only if you fight it...
How so? There is full coverage by the geostationary satellites.

Cospas-Sarsat System Overview
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Old 03-08-2013, 20:59   #727
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Re: Schooner Nina - MERGED 3 THREADS

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And as for EPIRB's.... there's big holes in the coverage... doubt if its advertised but then... 50/50 with is no worse than 50/50 without
There are no "big holes" in coverage for modern EPIRBs. They are detected by satellites in polar orbits (100% coverage of the planet), as well as by satellites in geosynchronous equatorial orbit (these will have gaps around the poles). It may take an hour for a polar-orbit satellite to go overhead, but the signal will be detected.

Boatman, could you be thinking about the "Spot" system? There are big holes in Spot coverage, but this is not the same thing as an EPIRB or PLB.
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Old 03-08-2013, 21:02   #728
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pirate Re: Schooner Nina - MERGED 3 THREADS

I just work on the basis that if a sat phone can't pick up a signal 6 times out of 10 in the S Pacific... an EPIRB is just as reliable...
But what the hell... some are believers... and some are not... some need something to believe in... others don't...
Unfortunately I've wiped all the mail etc from that trip so can't say if the phone was an Iridium or the other one... but contact with Oz going across was hit and miss
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Old 03-08-2013, 21:03   #729
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Originally Posted by boatman61 View Post
Did Bligh not have 12 or more in a smaller open boat... just saying... And as for EPIRB's.... there's big holes in the coverage... doubt if its advertised but then... 50/50 with is no worse than 50/50 without It may be all powerful... but only if you fight it...
Bligh had 18 on board, but was amply provided with food and water. He undertook the 3,700 mile journey to Timor in 47 days.

He was an extremely skilled navigator,one of the greatest and a considerable mathematical mind, having apprenticed himself to capt cook. Furthermore he was lucky and his destination was downwind in the main and he had reasonable weather.

Bligh was never lost , nor was his vessel seriously threatened. Comparisons with nina are not valid . nina was undertaking a shorter voyage , equipped with modern nav aids. She ended up in a bad storm You cannot fight an inanimate object. The ocean can generate conditions that are simply not survivable.

Epirb big holes in coverage . Please explain how a polar orbiting system doesn't cover the whole planet. ? , especially with 406mhz global mode operation. Dave
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Old 03-08-2013, 21:04   #730
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Re: Schooner Nina - MERGED 3 THREADS

And here is the coverage from the LEOSAR (Polar) Satellites.

The Cospas-Sarsat LEOSAR system provides global coverage for 406 MHz beacons. Below is a list of the sites where LEOSAR local user terminals (LEOLUTS) are located. Beacons that are activated in the areas shown in white on the map may have their transmissions detected and relayed to a LEOLUT for processing almost immediately, depending on the positions of overflying satellites. Transmissions of beacons activated in the blue areas are stored when they are received by the satellite and later transmitted to a LEOLUT when the satellite passes near that ground station. (See the GEOSAR coverage map for the locations where beacon alert transmissions can be relayed immediately at all times by the GEOSAR satellites, provided that they are no terrain or other obstructions of the signal.)


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Old 03-08-2013, 21:04   #731
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I just work on the basis that if a sat phone can't pick up a signal 6 times out of 10 in the S Pacific... an EPIRB is just as reliable...
But what the hell... some are believers... and some are not... some need something to believe in... others don't...
There are huge huge technical differences between sat phones and epirbs. There is no similarity. Dave
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Old 03-08-2013, 21:12   #732
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Re: Schooner Nina - MERGED 3 THREADS

I just work on the basis that if a sat phone can't pick up a signal 6 times out of 10 in the S Pacific... an EPIRB is just as reliable...
But what the hell... some are believers... and some are not... some need something to believe in... others don't...

And some compare apples with oranges and then just come up with their own unsubstantiated theories....
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Old 03-08-2013, 21:19   #733
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Goboatingnow. Thanks for your input. It is interesting that you say that there are many factors that can prevent EPIRB detection. Please expand on this?

Although the manner in which an EPIRB failed to work would be interesting, it would be enough for me to know the number of vessels that are fitted with EPIRBS and fail to complete a distress call that is recognised by the ground station and the number of received distress calls. It really doesn't matter if these figures are global or per area, provided I know the what the collection method is.
I'm involved in rescue. Unless the casualty ( ie the rescued) is specifically questioned , there is no way to determine if a Epirb was triggered but was not detected. Since the casualty is alive, by definition there was a successful rescue. Detailed stats are not kept or analysed. In some countries there are Investigation Agencies , but these are rarely judgemental or particularly analytical.

EPIRBS can fail to transmit for several reasons

(A) loss of power

(B) submerged or otherwise shielded antenna


(c) incorrectly deployed antenna , GEOSAT in particular is at extreme detection range

(d) not automatic initiation failure , ie the crew fail to reach the Epirb.

(E) failure of the internal electronics , specifically the transmitter.

(F) incorrect user activation

However the 406 system is a one way , beacon system , there is no standardised method of confirming beacon detection. , this is a major consideration for the proposed successor to cospas SARSAT.

What you ask for is impossible.

You cannot detect an Epirb that isn't detectable. End of story. You could collect anecdotal evidence from survivors , but given the unreliability of casualty evidence , I'd say its useless.
Dave
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Old 03-08-2013, 21:27   #734
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pirate Re: Schooner Nina - MERGED 3 THREADS

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Originally Posted by goboatingnow View Post
I'm involved in rescue. Unless the casualty ( ie the rescued) is specifically questioned , there is no way to determine if a Epirb was triggered but was not detected. Since the casualty is alive, by definition there was a successful rescue. Detailed stats are not kept or analysed. In some countries there are Investigation Agencies , but these are rarely judgemental or particularly analytical.

EPIRBS can fail to transmit for several reasons

(A) loss of power

(B) submerged or otherwise shielded antenna


(c) incorrectly deployed antenna , GEOSAT in particular is at extreme detection range

(d) not automatic initiation failure , ie the crew fail to reach the Epirb.

(E) failure of the internal electronics , specifically the transmitter.

(F) incorrect user activation

However the 406 system is a one way , beacon system , there is no standardised method of confirming beacon detection. , this is a major consideration for the proposed successor to cospas SARSAT.

What you ask for is impossible.

You cannot detect an Epirb that isn't detectable. End of story. You could collect anecdotal evidence from survivors , but given the unreliability of casualty evidence , I'd say its useless.
Dave
So... if I buy an EPIRB and my boat sinks... I jump in my dinghy coz liferafts suck... set off my EPIRB and get rescued by chance 20 days later... will I get my money back...?
Or are you saying there;s no guarantee...
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Old 03-08-2013, 21:34   #735
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Re: Schooner Nina - MERGED 3 THREADS

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Originally Posted by boatman61 View Post
I just work on the basis that if a sat phone can't pick up a signal 6 times out of 10 in the S Pacific... an EPIRB is just as reliable...
But what the hell... some are believers... and some are not... some need something to believe in... others don't...
Unfortunately I've wiped all the mail etc from that trip so can't say if the phone was an Iridium or the other one... but contact with Oz going across was hit and miss
Your satphone may have been a GlobalStar, or an Inmarsat, or an Idirium phone. The first two have coverage holes, but Iridium, which uses cross-linked polar-orbit satellites has truly global coverage. With Iridium you may have to wait a few minutes for a satellite to come into range, but you will pretty quickly get coverage. If you have a crappy antenna, or other gear problems, it might not work as well as it should.

The EPIRB polar-orbit satellites also need to fly over your location, which can take a little while. The satellite may need to store-and-forward the EPIRB data, if it isn't within range of an earth station.

This isn't a matter of belief, that's just how the system works.
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