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Old 23-03-2014, 08:00   #46
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Re: the basics for survival?

(Sorry for breaking these posts up, but they address too many points for a single post).

The lightning strike argument really tickles my funny bone. You are projecting a very low probability event (lightning strike) onto a lower probability event (taking out epirb) to bring fear into an even much lower probability event (the need to abandon boat). Multiplying these probabilities together (lightning strike taking out epirb and needing to use that epirb) brings your end-times scenario so close to zero as to be all out of perspective. You shouldn't even be on a boat, since everything about it carries much higher probability of risks than the above.

The lightning strike probabilities are well-known, as are the abandon ship ones (and they are extremely low). I will bet you that the probability of lighting taking out an epirb is so low that Mainsail may be the only person to have experienced it. We have been struck by lightning (taking out everything but the epirb), and personally know over a dozen people who have been struck by lighting - one who lost their boat from it. None of the epirbs were damaged.

Let's have some perspective.

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Old 23-03-2014, 08:28   #47
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Re: the basics for survival?

Okay, how's this for perspective. Below I have copied a post from a SSCA forum by a poster who is crew on SAR aircraft.

SSCA Forum • View topic - Reliability of EPIRB



by Kamaloha » Tue Feb 10, 2009 12:54 am

John, many thanks for the compliments. I'm not an expert on too many topics and I have learned a great deal from you and others on this forum about a great many cruising subjects. It is nice to be able to give something back. This is one area where I do have a little expertise. I've lectured to national pilot, medevac and SAR conferences on ELT/EPIRB/SARSAT technology, and I've served as our CAP state director of emergency services. For 23 years I've also made my living as a medevac helicopter paramedic, so I do worry about getting found if I go down. I'd be happy to post a link to some of my powerpoint presentations but they include a lot of photos of crashed aircraft so they are awfully big. They are also quite oriented toward the aviation community and land-based SAR, and a little off-topic for the cruising community.

Hellosailor, you raise some interesting conjectures, but they aren't borne out by the facts. The descriptions I gave are for current technology and standards, not past tense. The GPS receiver is still by far the most power hungry component of an EPIRB; nearly all modern GPSes use either the SiRF or the Rockwell chipset, and those weigh in at nearly a watt of power consumption. (I confess to not knowing what the chipset my McMurdo GPIRB uses.) By contrast the 121.5 MHz transmitter uses 100 mW (one tenth watt) at a duty cyle of 90%, for an average power consumption of 0.09 W, and the 406 MHz transmitter uses 5 watts at a duty cycle of < 1%, for an average power consumption of 50 mW. As far as the schedule of how frequently the GPS acquires a fix, that is mandated by the certification standard, and the numbers I gave are for the standard as revised in 2008, so it is not based upon obsolete ideas, but upon experience with the new units and the best of current thinking... so that really is how these things work.

As I described earlier, we've been able to track the 406 MHz data burst in our aircraft for as long as you've been able to transmit it; the Becker DF receiver was designed at the same time as the transmitters and it is the de facto standard for airborne search. Thus nearly all aircraft that are looking for you ARE looking at the 406 signal, but due to the reasons I described in my previous post it is the "rough cut" signal and we switch to the 121.5 MHz signal for the "finish work" as soon as we are able. As far as WHY the Becker does not display the GPS coordinates directly in the aircraft, that part I can't explain with authority, but I surmise it is because the system is designed such that the air crew is SUPPOSED to chase the homing signal, not the GPS coordinates, so having them displayed directly would tend to lead inexperienced air crews on wild goose chases. I was disappointed the first time I got to chase a real 406 only to discover that the Becker displays nothing useful; no MMSI, tail number, boat name, or coordinates, only the serial number of the unit, which must be referenced to the national database to get anything useful out of it. Bummer.

However, it is absolutely the case that search aircraft are homing on the 121.5 MHz signal you are transmitting right now, and not on a set of coordinates being encoded from the GPS. You are correct that overwater search crews do take into account drift as best they can. However, you missed my whole point, which is that we already have ten times more accuracy than we need to find you without the added information of the encoded coordinates. The satellite will locate you to within two miles without those coordinates, your homing signal has a range of at least twenty miles; and all I need to do is be able to receive your homing signal and I will find you. It's as simple as that. Having "more accurate" information to begin the search doesn't change my prosecution technique one iota - as soon as I can receive that homing signal, that's what I will be following. I'm not going to delay my prosecution by overflying the coordinates if I can receive your homing beacon; I'll be turning straight for you instead. All you need to worry about is me getting close enough to receive it.

Yes, 121.5 MHz EPIRBs are obsolete (and illegal) but that is not because they are harder to find. It was because of the astronomical falsing rate. They were designed to a very low cost and low reliability standard, and 99.4% of all activations were false alarms, and every false alarm required a crew to go look for it (actually not quite true, see below).

The SARSAT technology is completely different for the old vs. the new EPIRBs. On the old system (which was turned off completely ten days ago) low orbit "spy" satellites in polar trajectories carried the detection payloads. Since there were multiple satellites the period between overflights was irregular, but it averaged 45 minutes. It took two satellite passes with a positive signal hit to resolve the location ambiguity. Because of the astronomical falsing rate, initial satellite resolutions were NEVER prosecuted until a third positive pass. Thus a minimum of an hour and a half to two and a half hours elapsed before the first alarm bells rang to initiate a search.

With the new 406 system, the improved reliability standards mean that the false alarm rate is now 93%, still far from perfect but a vast improvement. Now there are detection packages flying on geostationary weather satellites. These are in a much higher orbit which is why they had to go to a five watt signal. However since you are always in view of a geostationary satellite the initial activation time is measured in seconds, not hours. The first steps used are to look up the serial number in the international MMSI database and call the series of contact numbers you have provided. This identifies nearly all the false alarms quickly without any search assets ever being dispatched - a phenomenal improvement over the old system.

But - and it is a big but - all that technological advancement is only used to improve false alarm detection and initial asset deployment. Once we are in the search area, it is the old fashioned 121.5 MHz homing signal that completes the mission and finds you, and the techniques we use are all but identical to what has been done since the first ELT's were deployed in 1964.

One final topic and I'll go to bed. You ask what I do or would own. My aircraft ELT is a GPS-enabled unit. I do not own a hiking PLB but if I did it would be a GPS-equipped unit. The reason for both of these is that an aircraft crash in the woods can be damnably hard to spot - it is amazing how an aircraft can just disappear into the trees. Further, once activated these signals will NOT be moving, so therefore the coordinates will represent an accurate position, and it is quite likely that an aircraft will never be dispatched at all; we'll just send in a ground team with an eTrex. After all, while is is nice to overfly a crash, an aircrew can only search and locate, it takes a ground team to search and rescue.

For the boat, I do own a McMurdo GPIRB. However I bought it before I had ever searched for one, before I took my AFRCC (Air Force Rescue Coordination Center) search management course, and before I understood the technology. In other words, I was just as taken in by the hype as everyone else. If I were buying it anew I would not bother with the GPS feature at sea. For individual use I see no need to attach a GPIRB to a lifejacket. I was resisting counseling anyone to do what I do, and you won't get any grief from me if you achieve greater peace of mind by upgrading - attitude is everything in a survival situation and you will want to feel you've done whatever is best in your own circumstances. It is just that the original poster was severely cash-limited, and adding the GPS almost doubled his price without statistically increasing his likelihood of being found. I don't wish to boast, but we train every month so I've found and watched others find hundreds of transmitters, and our success rate is 100%. If the radio is transmitting, we will find you, night or day, clouds or sunshine. It's as simple as that.

It hardly needs saying that none of this applies to the SPOT. Even if it did succeed in getting its message through, it got off the train at the first stop. No aircraft could possibly be equipped to home on it, since it only data bursts every five minutes, without a homing signal like an EPIRB/PLB, and I know of no aircraft receivers in existence that will receive and decode it.

Hopefully I've presented the information you need to make a decision you are comfortable with - and will be effective should the need ever arise. Good luck!
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Old 23-03-2014, 08:39   #48
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Re: the basics for survival?

Another thing Callahan had was Dougal Robertson's book on survival at sea which included ocean current direction, wind speed, and rainfall amounts etc worldwide for different times of the year. It also had the migratory bird flight paths included as well as which birds ventured offshore and about how far off.

Other tips were which clouds may be the type that are generally above a land mass.

The Robertsons were a family adrift for like 38 days so water was at a premium. So for additional hydration they used some rather drastic but very smart methods.

They used the crappy water that had collected in the boat that had mixed with rainwater in an enema. This method of hydration helped since I believe there were six people in the 9'-10' dinghy after the life raft failed.

Also Callahan had a spear gun and some fishing tackle. He also made a couple lures for fishing.

http://en.wikipedia.org/wiki/Dougal_Robertson

Sea Survival: A Manual: Dougal Robertson: 9780275527600: Amazon.com: Books
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Old 23-03-2014, 09:11   #49
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Re: the basics for survival?

This would be so nice if EPIRBs had some sort of receipt confirmation built in. It might help keep the spirits up.

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Old 23-03-2014, 09:17   #50
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Re: the basics for survival?

This would be so nice to be in a lifeboat rather than in a liferaft. At least having the option of doing something getting somewhere rather than being in a liferaft, stuck dead in the middle of a big ocean.

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Old 23-03-2014, 09:37   #51
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Re: the basics for survival?

I just don't buy the positioning of this argument. Saying that one should prepare themselves to handle an emergency at sea if they are real seamen, then rolling that into how much should be carried in a liferaft while knocking someone who expects to pull the EPIRB button in that situation just smacks of hype rather than thinking through the issues. Preparing the boat and staying on the boat is clearly far more important than spending money on more complete liferafts. Being setup to deal with fires, de-watering and mechanical and hull repair are far, far ahead of spending extra on sail-rigs for life-boats and long term water creation capability for your life raft. I think Evans on Hawk has given a pretty rational argument as to why he believes having a liferaft decreases survivability.
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3. We have taken what some consider an extreme position regarding life rafts (not to carry one), but it is in fact a supremely practical position and not a purist position. After a lot of study and evaluation, I honestly believe that carrying a life raft decreases the likelihood of saving a vessel and decreases crew safety. I honestly believe it distracts the crew from the primary mission of staying with and saving the vessel.....
FAQs
I have a liferaft onboard, but sure don't put a lot of faith in it. If I was going spend more on these type of devices it would be to add a second EPIRB.
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Old 23-03-2014, 09:47   #52
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Re: the basics for survival?

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Originally Posted by Delancey View Post
Okay, how's this for perspective. Below I have copied a post from a SSCA forum by a poster who is crew on SAR aircraft.
I don't understand your point. I read that message as a very big positive for modern epirbs and SAR. He states that they know your position within seconds and that SAR is immediately coordinated - a "phenomenal improvement" in his words. He also relates how they no longer have to search large areas looking for a signal. It does not address anything about probability of the epirb not working or being hit by lightning, etc. Nor does it address the "end of times" scenarios brought up here.

BTW, Charlie on Kamaloha (the person who wrote the post) is sitting right here with me now if you have any questions you would like him to address.

So the previous poster is correct - the days of Steve Callahan type experiences are over. Yes, lessons can be learned from him and others in the past, but planning for being adrift for over two months is not a realistic or probabilistic scenario anymore. Your time and energy is much better spent planning for up to one week by planning your SAR notification preparedness. If you are concerned about your main epirb not working, plan for that in other ways besides building and stocking a lifeboat/raft for 3 months of survival.

And have perspective. If you are cruising the Med, why spend all that time, space and money preparing for end of times survival at sea?

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Old 23-03-2014, 09:53   #53
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Re: the basics for survival?

Hi Charlie-

In the post you stated you had been witness to 100% success rate in finding beacons if the radio was transmitting. Would you care to comment on your success rate in finding beacons that fail to transmit?

Thanks
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Old 23-03-2014, 09:57   #54
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Re: the basics for survival?

Oh come on - I'm not even going to ask him to address that question because it is silly. Of course if there is no epirb activation (for whatever reason), there will be no SAR even launched.

Your argument is a non-sequitar and tries to involve proving a negative at the same time.

Let me try: how many people have survived in a liferaft but have never been found?

See how easy that is?

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Old 23-03-2014, 10:05   #55
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Re: the basics for survival?

Then I guess you shouldn't bother asking him if he doesn't think it's worth the bother to test EPIRBs because they are always 100% reliable and will always function properly when called upon.
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Old 23-03-2014, 10:16   #56
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Re: the basics for survival?

Again, a non-sequitar deflection of an argument. I think you purposefully do this for fun!

No one ever said epirbs should not be tested, and your question did not ask for that information.

Of course epirbs should be tested. - who said they shouldn't? And liferafts should be routinely checked and repacked. And fluid levels should be checked on engines, etc.

Nobody has stated that epirbs are 100% reliable. I am stating that liferafts are not 100% reliable. I am also stating my belief that liferaft failures are more common than epirb failures, and that there are more out-of-compliance liferafts than there are epirbs.

What is your point? Can you state it clearly and consistently?

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Old 23-03-2014, 10:17   #57
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Re: the basics for survival?

The things that can be learned from "the days of Steven Callahan" are for general knowledge. I very much doubt folks will actually stock up for a 3 month drift.

Also the things that can be learned from Dougal Robertson's Book still apply. It's simply more knowledge. This knowledge can help you better prepare.

Just knowing the direction of the current, the normal wind direction for the time of year, and average rainfall in the location you are in can be very helpful.

Tom
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Old 23-03-2014, 10:18   #58
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Re: the basics for survival?

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The things that can be learned from "the days of Steven Callahan" are for general knowledge. I very much doubt folks will actually stock up for a 3 month drift.
For that matter, Steven Callahan did not stock up for a 3 month drift.

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Old 23-03-2014, 10:22   #59
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Re: the basics for survival?

I make sure that I am overweight so I carry extra food with me at all times.

Isn't it the case that rescue services are not available everywhere in the world?
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Old 23-03-2014, 10:31   #60
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Re: the basics for survival?

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I don't understand. Are you proposing that there should be no emergency notification of a vessel in distress or a person clinging to life in a raft, and no response made available anyway? You think the best thing is to be so prepared, that you will float around for up to a year (or more) until your raft drifts onto habitable land? And once there, you will get a job and earn the money for the medical care you will desperately need? After you build yourself a house to live in while doing so?

Or is your problem that technology allows a 3-4 day response from almost every corner of the globe, but you think that takes the fun out of abandoning a boat and prefer to see that response downgraded to 30-40 days?

You think it is admirable that people take responsibility for their own survival only as long as that survival means more than a month (or some other randomly chosen "he-man" time)? And it is a symptom of a selfish and sick society that people take responsibility for their own survival for up to only a week?

How about this for perspective: Technology now allows SAR to pinpoint locations so that the mission costs much less, the rescue can be coordinated with and handed off to the agency/country that is best capable of the job, only necessary equipment is used and the SAR people are better prepared.

In the past, whole swaths of ocean would be fruitlessly searched by multiple agencies/countries at great cost with no idea of the weather or conditions the SAR team might need to operate in.

Your point doesn't make any sense to me.

Mark
Really? Then where is flight 370? And all aboard?

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