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Old 01-28-2007, 05:19 PM
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need feedback for a purchase of a class1 406 epirb/built in gps. What are considered the best brands and models?
Old 01-28-2007, 07:17 PM
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ACR GlobalFix 406, its the only one worth buying..
Old 01-29-2007, 04:22 PM
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SWFLNavigation - 1/29/2007 4:17 PM

ACR GlobalFix 406, its the only one worth buying..
I think what SWFLNav is saying is that the ACR GlobalFix 406 with an internal GPS source is the best one out there, and I will agree with that ... unless you are on the West Coast or Alaska boating in cold water. In that case I would recommend the ACR 406 RapidFix with an external GPS source.

However ... Simrad has recently entered the EPIRB market. Don't know the product(s) yet, don't know their availability, but it has to be top quality if/when it arrives in the US market. My understanding is Simrad has a GPS embedded unit like the ACR GlobalFix and an EPIRB that accepts an external GPS signal like the ACR RapidFix.

Anyone have any info on the new Simrad EPIRBs ???


Old 01-29-2007, 09:22 PM
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Eyeball - 1/29/2007 4:22 PM

[unless you are on the West Coast or Alaska boating in cold water. In that case I would recommend the ACR 406 RapidFix with an external GPS source.
Why would an external GPS be advantageous anywhere ?

Old 01-29-2007, 10:08 PM
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Becuase it already has the position aquired via the external GPS instead of waiting the the unit to aquire on its own. I wont say its the best way but it is an option. If you lost all power on the boat and took time to figure it out, you may be in trouble later.
Old 01-29-2007, 10:17 PM
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Default Re: epirb

ACR GlobalFix 406.
Old 01-29-2007, 10:25 PM
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ACR GlobalFix 406s acquire position in under 10 minutes. When I did the once every 5 year test, mine acquired the position in under 45 seconds. Why take a chance on bad fixes, leaks, stray voltage, etc that can occur with an external GPS unit? Either way, the beacon distress signal starts as soon as the EPIRB is activated, which starts the SAR chain of events. By the time the beacon is confirmed, the GPS will have acquired a fix and uplinked it to the satellite. All of this will have occurred before the helo takes off (unless of course the boat was already in contact with the USCG, in which case, the EPIRB was probably superfluous since the position would have been transmitted by DSC or voice).

Harry
Old 01-29-2007, 10:58 PM
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SWFLNavigation - 1/29/2007 10:08 PM

Because it already has the position aquired via the external GPS instead of waiting the the unit to aquire on its own. I wont say its the best way but it is an option. If you lost all power on the boat and took time to figure it out, you may be in trouble later.
The Epirb with the GPS interface gets its position updated every 20 minutes from the GPS. Once activated the position is no longer updated (even if the GPS is still connected).

The GPS equipped EPIRB may take a little longer to acquire a fix, but the position transmitted will be the location of the EPIRB, not a position that it was at up to 20 minutes in the past.

Ed
Old 01-30-2007, 07:33 AM
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Default Re: epirb

If the GlobalFix is connected to a GPS, does it get continuously updated ?

The reason that I ask is that my ACR PLB (with internal GPS) will only accept external GPS by pressing a button (of course after the cable is connected). It is not continuously updated



Old 01-30-2007, 01:36 PM
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out of pocket in salt lake. will answer online tonight . chris ps cell phone typing sucks!
Old 01-30-2007, 03:52 PM
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Harry Brosofsky - 1/30/2007 7:25 PM

ACR GlobalFix 406s acquire position in under 10 minutes. ... Harry

Funny how all the warm water guys don't have a clue about the reality of cold water. Harry, those 10-mins may be all you get in life. In cold water I wouldn’t want to risk a GlobalFix not acquiring and broadcasting an immediate GPS coordinate. It if doesn’t, you’re dead. EPIRB activation to local SAR coordination is about 15-mins. USCG on the west coast says an average of 20-mins to find someone in the water when they have a coord. You’ve now been in the water 35-mins. If it takes a GlobalFix more than 10-minutes to acquire a coordinate and send a signal your GlobalFix EPIRB will only be functioning as a dead body locator.

In cold water every minute counts. Survivability in the water off Northern Calif is 45-minutes. That's all! Some folks (the fat ones) last longer, some folks (the skinny ones) won’t last 45-mins. And the water just keeps getting colder and the survival time shorter the further north you go.

For all of you warm water guys, here's how the N Calif coastal waters work; a couple years ago a guy fell over the side of a sailboat just outside of San Francisco Bay. He was wearing a PFD, the crew saw him go over, they waved to each other to acknowledge the event, and the boat immediately maneuvered back around to pick the guy up. By the time the boat got turned around and back to him he was already dead, cause: hypothermia.

Warm water – GlobalFix
Cold water – RapidFix

That said, everyone should buy the EPIRB they are most comfortable with. Just be sure to make it an ACR product.



QUESTION: does anyone have any info on the Simrad EPIRBs? ;?

Old 01-30-2007, 04:16 PM
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Elusive - 1/30/2007 6:22 PM

Eyeball - 1/29/2007 4:22 PM

[unless you are on the West Coast or Alaska boating in cold water. In that case I would recommend the ACR 406 RapidFix with an external GPS source.
Why would an external GPS be advantageous anywhere ?
It is advantageous anytime you need to (a) immediately broadcast a location, or (b) get a lock on the GPS sats when conditions prevent your EPIRB from locking onto the sats.

I believe the GlobalFix will attempt to lock on and (re)broadcast its location every 20-mins once activated. So if you were in rapid currents the GlobalFix would be reporting your (its) drift. That’s a good thing if you stay together, but could become a nightmare if you and your EPIRB are separated.

That’s why I said choosing the right EPIRB it is not necessarily an easy choice to make.
Old 01-30-2007, 05:43 PM
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Default Re: epirb

It's interesting that ACR's EPIRB's offer either onboard GPS (GlobalFix) OR external GPS (RapidFix) but not both

My ACR AquaFix PLB offers both. The only downside to the external GPS connection, as mentioned before, is that you must press a button to store the present location whereas the RapidFix constantly stores the location

It seems to me that a unit that constantly updates AND has an onboard GPS would be the optimum configuration




Old 01-30-2007, 06:33 PM
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Default Re: epirb

ACRGuy - can you provide some info on your new ResQFix PLB?

1 - are the specs better/same as/worse than current AquaFix 406?
2 - Does this replace the AquaFix 406 in your product line
3 - will this really ship in February, if so 1st, 2nd week, etc. when?

Thanks
Old 01-30-2007, 10:05 PM
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Wow. You guys have opened up so many cans of worms I should just go fishing. I just got in from Salt Lake and I'm beat. I'll see if I can add some info here tonight and get the rest tomorrow at work.

First of all, thanks for the support.

Ok a little history. When NOAA first started talking about the ability to add GPS data to the distress message there was a mad scramble to add GPS data to the distress message. ACR knew that an internal GPS would have a hard time acquiring data being in close proximity to a 121.5 MHz transmitter. We were the last one to market with an internal GPS because we were not satisfied that an internal GPS would acquire in real world conditions. More research and testing was needed and our engineers spent the next year making sure that our internal GPS could acquirer outside the lab.

In mean time the concept of interfacing with an internal GPS was proven and brought to fruition. An EPIRB that accepts data from an external GPS (that is already on) is still the fastest way to get Lat/ Long into the distress message. Most EPIRBs on the market (by rule) transmit their first 406 data burst between 50 and 100 seconds after the beacon is activated. If the GPS data is already in the beacon it will be added to the first distress message.

Let's look at the benefit of GPS data in EPIRBs. As we all know GPS is an enhancement to the 406 MHz EPIRB. According to COSPAS-SARSAT worldwide on average it takes 1 hour to hear the beacon, derive a position from Doppler shift, get the information out of the registration data base, contact the closest rescue asset and give them a mission. That's world wide on average. This all happens with the aid of the LEO SAR polar orbiting satellites. There is another group of satellites called GOES. These are geostationary and cannot get a Doppler position but they can hear the beacon and get the process started.

The GOES satellites have the ability to accept GPS data with the 406 distress message. When this happens the worldwide average is reduced by 45 minutes. Getting GPS data in the distress message early in the activation provides the greatest benefit. We have seen activations that have gone thru GOES only and a mission was launched before the next LEO came over the horizon.

Your beacon transmits a unique hexadecimal ID #. The GPS data is appended to that. Once the GPS data is transmitted beacons are not allow to update that position for twenty minutes. Otherwise the computers would believe there is a second activation and a third and so on every time the beacon transmits. Twenty minuets later the beacon can send a new GPS position meanwhile the LEOs are refining the Doppler position. This new position will not change who gets the call even if the data is twenty minutes old.

Once a mission is launched, continual updates are available for the searchers if they need it. Each mission is also unique. some are prosecuted very quickly and easily, while others seem to have the odds stacked against them. (distance, available assets, bad weather) Having an internal GPS that continually updates the beacon position (IMO) is not as important as getting the GPS data in the first or second data burst.

With all that said, our internal GPS is very good at acquiring data from a cold start even with all the interference from the transmitter. This is thanks to our engineers and not wanting to rush life saving equipment to market. (I beg forgiveness from Wiley for this self promotion)

I will talk more in the morning about some of the other questions regarding GPS interfacing.

Stay Safe

Chris

Old 01-30-2007, 10:46 PM
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Default Re: epirb

Eyeball - 1/30/2007 3:52 PM

Harry Brosofsky - 1/30/2007 7:25 PM

ACR GlobalFix 406s acquire position in under 10 minutes. ... Harry

Funny how all the warm water guys don't have a clue about the reality of cold water. Harry, those 10-mins may be all you get in life. In cold water I wouldn’t want to risk a GlobalFix not acquiring and broadcasting an immediate GPS coordinate. It if doesn’t, you’re dead. EPIRB activation to local SAR coordination is about 15-mins. USCG on the west coast says an average of 20-mins to find someone in the water when they have a coord. You’ve now been in the water 35-mins. If it takes a GlobalFix more than 10-minutes to acquire a coordinate and send a signal your GlobalFix EPIRB will only be functioning as a dead body locator.

In cold water every minute counts. Survivability in the water off Northern Calif is 45-minutes. That's all! Some folks (the fat ones) last longer, some folks (the skinny ones) won’t last 45-mins. And the water just keeps getting colder and the survival time shorter the further north you go.

For all of you warm water guys, here's how the N Calif coastal waters work; a couple years ago a guy fell over the side of a sailboat just outside of San Francisco Bay. He was wearing a PFD, the crew saw him go over, they waved to each other to acknowledge the event, and the boat immediately maneuvered back around to pick the guy up. By the time the boat got turned around and back to him he was already dead, cause: hypothermia.

Warm water – GlobalFix
Cold water – RapidFix

That said, everyone should buy the EPIRB they are most comfortable with. Just be sure to make it an ACR product.



QUESTION: does anyone have any info on the Simrad EPIRBs? ;?
Speaking of cold water, I lived in Alaska one summer and a light airplane had an engine failure while crossing the Cook inlet into Anchorage. As bad luck would have it, he was unable to make it across the rather narrow stretch of water. Based on his distress call to the Merrill Field tower a civil helicoptor was given vectors to the ditching airplane and asked to render any available assistance.

The airplane ditched in the inlet while the helicoptor sat down beside him on floats. The airplane pilot was able to swim the short distance to the helicopter but by the time he got there he was too weak and disoriented to pull himself onto one of the floats. The helicoptor pilot shut down the helicopter and went out to drag the poor fellow into the helicopter. I believe he spent a few days in the local hospital recovering from hypothermia.

Every boat I ever saw in Alaska carried a raft on the top of the boat and the ones I rode in usually had float coats or cold water suits to get into.

Harry, correct me if I am wrong (you too Chris) but it seems that too many focus on the GPS coordinates as if the SAR crew flies to them to make the rescue. Doesn't the GPS coordinate just get you to the general location and then the pilot homes in on the 121.5 or 243.0 signal until a visual is made?
Old 01-30-2007, 10:57 PM
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Eyeball,

You make a lot of assumptions by calling me a warm water guy. I grew up boating in Maine and New Foundland, flew numerous overwater missions off of the central and northern CA coast, did a stint in AK, etc.

Now, regarding the rest of your post, and bearing in mind that I was in the SAR business until about 6 months ago (when I moved into a spec ops mission area), I contend that your assumptions are generally baseless. The 35 minutes you quote is an average. 15 minutes notification, 1 minute for every 2 miles from the launch point to the search area, and then a point search. Even with spot on coordinates, you're still over 45 minutes if more than 60 miles from a helo base. And I'm not even counting the time to actually effect the rescue, which could be anywhere from 3-15 minutes depending on sea state, winds, etc. And that's assuming that you are right with your EPIRB, that the weather is perfect and it is day time, that there are not other rescues going on that will prevent SAR from coming to you right away, etc...remember Mr Murphy. Considering how few and far between USCG/USAF SAR stations and boat capable ships can be, expect to be in the water a lot longer than 45 minutes.

Also, you mention that the internal GPS may not resolve a location...that's true. But it is also true that the link on a non-internal unit is good, that the GPS is outpurring data and that the data is valid, etc. I'll stick with the onboard GPS.

Finally, your scenario assumes that the coordinates are not updated during that 35 minute SAR mission you claim is average...in reality, the internal GPS EPIRB will have uplinked coords and those coords will have been pushed to the SAR crew while they are enroute.

As an aside, 45 minutes is time of useful consciouness in 54 degree water...you'll live for another 5 hours give or take. In summer, most of the CA coast is above that, but that's not really an issue anyway.

Bottom line...if you boat in cold waters, get a raft, wear a PFD and exposure suit, wear a tether, etc. The EPIRB will just help them find your dead body without some or all of those items. And if you can't afford all of those things...start with a raft (exposure suit if you boat in cold waters) and then go from there.

Harry
Old 01-30-2007, 11:05 PM
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jethro1 - Harry, correct me if I am wrong (you too Chris) but it seems that too many focus on the GPS coordinates as if the SAR crew flies to them to make the rescue. Doesn't the GPS coordinate just get you to the general location and then the pilot homes in on the 121.5 or 243.0 signal until a visual is made?
Generally, this is correct. The crew launches on basic info and starts to the LKP (last known position). While enroute, the position fix is updated if available. As the helo gets closer to the coords, the crew uses homing to get very close and ultimate uses visual search in the end game (which is why newer EPIRBs have strobes and why you should have ready access to smokes in your ditch bag).

On the active duty HH-60s I flew, we had UHF homing, but not VHF homing. There are techniques for homing without homing equipment, but they take time as they rely on plotting signal heard and signal fade positions from several directions and then plotting the intersection of the perpendicualr bisector of each set of SH/SF coords.

Harry
Old 01-30-2007, 11:53 PM
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ACRguy - 1/31/2007 7:05 PM

... Having an internal GPS that continually updates the beacon position (IMO) is not as important as getting the GPS data in the first or second data burst.

That is exactly what the USCG told me regarding EPIRB initiated SAR in my area. How it works in other areas may be different.


Old 01-31-2007, 12:22 AM
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Default Re: epirb

Eyeball - 1/30/2007 11:53 PM

ACRguy - 1/31/2007 7:05 PM

... Having an internal GPS that continually updates the beacon position (IMO) is not as important as getting the GPS data in the first or second data burst.

That is exactly what the USCG told me regarding EPIRB initiated SAR in my area. How it works in other areas may be different.

Yes - if you are in a slow boat in an area with minimal currents the GPS interfaced EPIRB will not be far off even in the worst case scenario (i.e you go down 19 minutes after the latest position update). In a boat that cruises at 36 knots crossing the Gulf Stream (4 knot current) or similar current the broadcast position could be wrong by as much as 12 nm when the EPIRB is activated and at a 4 knot drift things are getting worse rapidly as the interfaced EPIRB will not continue to update position. As course and speed information is not broadcast that makes for a 24 nm circle of error.

The GPS interfaced EPIRB also has the potential to transmit stale data if it is not connected to the GPS on a trip. It retains the last known position and will transmit that on activation unless the EPIRB battery is disconnected or the EPIRB is activated and reset.


Ed

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