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Old 07-10-2015, 16:52   #121
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Re: Safety of Ships' Lifeboats in Major Storms

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Old 07-10-2015, 18:04   #122
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Re: Safety of Ships' Lifeboats in Major Storms

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Originally Posted by Steady Hand View Post
Hi.

What follows is written in a friendly tone and not an argumentative one.

I can't speak for ASTBoone, who has a career background in SAR, but my understanding of what he wrote and when he mentioned "ping" by a EPIRB, is that the EPIRB, if still on a sunken ship would not "ping" its location to SAR assets (like a aircraft's "Black Box Flight Recorder").

I could be wrong on that interpretation of what was written earlier, but that is how I understood the earlier post.

I think laymen today would be asking "Why can't the Coast Guard find that ship?" Because laymen are accustomed to watching news reports of aircraft wrecks being located and Black Boxes being located remotely by "pinging" signals.
Correct Steady Hand, aircraft have "pingers" in them and are used to locate a sunken aircraft and yes they ping. But that's not what I was talking about. Thanks anyways ha.

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A EPIRB, once activated will send a continuous / alternating signal on both 406 MHz and 121.5. whirl whirl whirl.
The EPIRB dosen't need batteries to push the 406 MHz signal to the satellite, it needs the batteries to power the GPS and the 5 watt transmitter. They run continuously for 48+ hrs. The PLB is basically a digitized EPIRB in a smaller package and they operate from 24 to 48 hours continuously on a 5 watt transmitter as well.
The 121.5 MHz signal is no longer received by satellites, since 2007. The 406 MHz signal is much more enhanced, precise, and will tell SAR that you are in distress, who you are, where you are, and other pertinent information within minutes. The 121.5 signal is alternated with the 406 signal to reach line of sight vessels and yes, aircraft monitoring 121.5.
Back in my day (retired in 96) they only had 121.5 and we did not pick up the whril sound until we were about 30 miles out.
Today, the C-130s that you saw flying on this case can pick up and lock on (DF) to the 406 MHz signal from 150 miles out.
I stress electronic signals. EPIRBs are nice but if you have a PLB strapped to your belt, they're going to find YOU, not your EPIRB.
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Old 07-10-2015, 19:57   #123
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Re: Safety of Ships' Lifeboats in Major Storms

That is the reason that "jargon" is expressly prohibited by FEMA and DHS. You may think "ping" means sending out an acoustic pulse. To someone in the IT fields, it means sending out a data burst rather than an acoustic one.


And no, an EPIRB does NOT send continuous transmissions to the satellite network. It does not "alternate" between the aviation emergency channel and the satnet channel either, it sends continuously on the one (last I heard) and only "pings" updates on the other. I'd be glad to hear otherwise from anyone current on the field.


EPIRBs, as radio transmitters, won't do squat once submerged. They'll sting "ping" and "squeal" on the satellite and aviation frequencies, until they reach crush depth and are flooded. But given how well radio waves penetrate seawater...you'd have to be right next to them to hear them. And they reach crush depth (water resistance exceeded) very quickly.


ACOUSTIC pingers on aircraft black boxes (which are orange) are specially designed, as acoustic pingers, to be heard where radio waves can't go.


In the IT field, which is where SAR/SAT communications come closest, a device PINGS the network, or the server, and the response is sometimes called a PONG. No acoustics involved.
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Old 07-10-2015, 20:59   #124
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Re: Safety of Ships' Lifeboats in Major Storms

Re EPIRB (& PLB), Hellosailor has it pretty right.

These beacons once activated transmit continiously on a AM carrier of 121.5Mhz with a power output of around half a watt. This transmission continues until the battery is exhausted. This signal is used for localised homing.

Simultaneously they transmit a ditigal signal on a 406 Mhz carrier. This is the signal that is received by the satellite network. This transmission is sent in busts each of about 500 millisecsonds and repeats about every minute. It has power of 5 watts.They continue for 48 hours in most cases for EPIRBs and 24 hours for PLBs. After that time they are shut down internally to reserve remaining battery for the 121.5 MHz transmitter.

Newer direction finding equipment fitted to some SAR aircraft can home on these shorts busts.

The 406 signal has fair bit of data inbedded into it. Usually serial number or MMSI and GPS coordinates (if available) etc.
The first bust of 406 occurs very shorty after turn on (milliseconds) however this coded as a test signal and is not considered by the SARSAT COSPAS signal as a live distress signal. The second bust about 1 minute later is coded as a live distress signal.

As far as embedded GPS data is concerned, this is handled in various ways by different manufacturers. Some only fire up the GPS engine for the first twenty minutes, others for longer and some continously. It is all about battery drain and thus battery life.

Not that it really matters but I make part of a living out of installing, testing, repairing beacons and homing equipment
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Old 07-10-2015, 21:18   #125
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Re: Safety of Ships' Lifeboats in Major Storms

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Note: The El Faro was a ship with both containers on the top deck, and a RORO design middle deck that had vehicles and trailers.
From cargo security and ship stability points of view this appears to be a disaster waiting to happen and might explain the 15 degree list?
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Old 07-10-2015, 21:23   #126
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Re: Safety of Ships' Lifeboats in Major Storms

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Originally Posted by hellosailor View Post
That is the reason that "jargon" is expressly prohibited by FEMA and DHS. You may think "ping" means sending out an acoustic pulse. To someone in the IT fields, it means sending out a data burst rather than an acoustic one.


And no, an EPIRB does NOT send continuous transmissions to the satellite network. It does not "alternate" between the aviation emergency channel and the satnet channel either, it sends continuously on the one (last I heard) and only "pings" updates on the other. I'd be glad to hear otherwise from anyone current on the field.


EPIRBs, as radio transmitters, won't do squat once submerged. They'll sting "ping" and "squeal" on the satellite and aviation frequencies, until they reach crush depth and are flooded. But given how well radio waves penetrate seawater...you'd have to be right next to them to hear them. And they reach crush depth (water resistance exceeded) very quickly.


ACOUSTIC pingers on aircraft black boxes (which are orange) are specially designed, as acoustic pingers, to be heard where radio waves can't go.


In the IT field, which is where SAR/SAT communications come closest, a device PINGS the network, or the server, and the response is sometimes called a PONG. No acoustics involved.
Man you lost me on that one. Didn't mean to make you go IT on me. I officially retract my previous statement that EPIRBs don't ping. Good grief!
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Old 07-10-2015, 21:42   #127
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Re: Safety of Ships' Lifeboats in Major Storms

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Originally Posted by Doug Brown View Post
Unless the lifeboats have been upgraded over the years, they are probably the "open" type. Depending on the seas and if they are in good enough condition to float, they would offer some protection, but probably very little in a Cat 4 hurricane.

What can go wrong? Just about everything that you can imagine...

If they had not yet launched them and the ship was already listing 15-deg, the main problems that come to mind are that the davits and falls were a fur ball of rust and would not operate or the crew didn't know how to operate them.

I don't think launching a lifeboat could be done in Cat 4 conditions.

I hope they made it.
According to gCaptain the lifeboats were open style.

On a Jones Act ship any problems with the lifeboats are not going to be as blatent as the davits and falls don't work or the crew doesn't know what they are doing.

The way I see the ultimate bailaout vessel would be one of the fully enclosed free-fall life boats. As long as you didn't hit the mother ship dropping in or immediately after, you should be OK even in a Cat4 or Cat5.
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Old 08-10-2015, 05:05   #128
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Re: Safety of Ships' Lifeboats in Major Storms

Quote:
...I don't know, are ships operating in Caribbean waters required to have immersion suits on board? Does anyone know?...
I believe that regulations for cargo ships and bulk carriers trading outside the parallels 20 degrees north or 20 degrees south have stipulated that one fully approved immersion or abandonment suit must be carried for each crew member.
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Old 08-10-2015, 05:49   #129
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Re: Safety of Ships' Lifeboats in Major Storms

No they're not required but a lot of ships have them in case their trade route changes they're ready.
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Old 08-10-2015, 11:03   #130
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Re: Safety of Ships' Lifeboats in Major Storms

Gordon was nearly right, the limits are 30N and 30S.
https://www.gov.im/lib/docs/ded/ship...rthecarria.pdf
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Old 14-10-2015, 14:50   #131
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Re: Safety of Ships' Lifeboats in Major Storms

Apologies for being absent, here. The dongle supplying our Internet reception failed, and it's taken a while to come back to Noumea and replace it.

Thank you very much, all you professionals who supplied real information.

Ann
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