EPIRB

Given the way this thread has evolved, I thought I'd add the obvious at this point about why I chose to buy replacement batteries already assembled for my model and not McGuiver some hack (even tho that's generally my approach) myself.  I sure didn't feel like spending $150 for ACR to do the job, but having my own solder job on battery connections lead to my own death was not appealing either.  This is an epirb after all, not a fish finder or my flashlight.   There's a ton of articles out there written about (and describing the issues) of doing DYI on epirb/plb battery replacement, I'm sure you've probably read some of those but here's one for an example and why I decided saving a couple dollars was not worth losing my life when I found that my epirb didn't work when I really needed it. 

https://www.advrider.com/f/threads/acr-resqlink-plb-dissassembly-aka-the-10-battery-replacement.749245/

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Love the DIY too, but when my ResQLink hits another five years (soon), I'm sure I'll be mailing it in for their battery replacement.

For my model, it’s just $40 (total) for the battery pack, so I can’t see trying to solder one together myself, even if my soldering skills were much better. But having taken it apart and replaced the battery, I don’t have any problem with the replacement step. If you feel it’s safer to send it in for battery replacement, of course, I don’t have any problem with that either, as that was also my first reaction.

I hadn’t considered the limit of 12 GPS tests per battery pack. Does anybody know if that’s automatically reset when the battery pack is disconnected?

Sorry I never meant to stir the pot. Just wanted to point out the savings. I understand some people just don't want to bother with learning about batteries, and choose to entrust manufacturers or 3rd party vendors. There's nothing wrong with that if it gives you a peace of mind. With that said, there is nothing in those packs that make them more safe. If they are using off-the-shelf batteries, and if you're using same identical batteries, there is no way that their packs are more safe than yours. If you follow the proper way to construct battery packs, you can make your own pack more safe than oem or 3rd party packs because you are in control in every step of the construction. You know what batteries goes into your pack. You know the quality of the construction. But of course you have to test the battery you use.

One very important thing I must point out. The word "solder" is used several times. It's also mentioned in the posts referenced. Please know this, NEVER solder batteries. You always spot-weld batteries by joining them with nickel strips. If you were to make a proper solder joint, it would put too much heat on the battery. It cooks the compound inside, increases the internal resistance, and it can melt the protective wrap. It shortens the lifespan of the batteries and can make them unsafe. Nowadays, spot-welders for making battery packs, as well as other necessary materials, are widely available and are inexpensive. You can pick up a low end spot-welder for under $50.

"I hadn’t considered the limit of 12 GPS tests per battery pack."
I wonder how they can impose that? Is it restricted by the device, or is it imposed by the account your device is registered to? I have no idea how an EPIRB operates.

"I hadn’t considered the limit of 12 GPS tests per battery pack."
I wonder how they can impose that? Is it restricted by the device, or is it imposed by the account your device is registered to? I have no idea how an EPIRB operates.

From my perspective, the more pot stirring the better...

It's a good question as to how the 12 tests is determined. On the PLB website, it says

"An ACR ResQLink+ beacon has enough excess battery life to perform 12 GPS self tests over the 5 year life of the battery"

That makes me think that nobody is keeping track, and it's only based on available battery life.

Why do you have an EPIRB?

It's a PLB, which is the hand-held equivalent of what you're probably thinking of. IMHO, it's a good thing to consider carrying when kayak fishing. Hopefully, you'll never need to use, but if you do, it could be a life-saver. I think this is the one I have:

https://www.acrartex.com/products/resqlink-400/

I'll simplify that further. I'm married, have two kids, and ocean kayak fishing is inherently dangerous. An epirb is super cheap insurance.

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I know what EPIRB is … and I know what it isn’t. My question was “WHY” do you have and EPIRB?

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs in a perfect world where everything goes right and all data is complete, and handed-off first pass from EPIRB to sat and then first pass from sat to sat, and then first pass from sat to ComCen, ComCen verifying authenticity of a rescue and handing off to SF CG, and using the SF CG average on-site time of 20-mins from notification. 2-hours.

EPIRB was designed for transoceanic vessels with capabilities for crew to survive for days while awaiting rescue. Think container ships with ‘pods’ for the crew to live in while waiting. There is nothing “instant” about EPIRB, it is not like dialing 9-1-1 and someone immediately answers.

You have an option. It is expensive. Keeping in mind the average time from when the SF CG receives a ‘distress’ notice to being on-site is 20-mins, and all of the CA coast is CG VHF radio monitored from shore to many miles out, VHF may be a better option for ‘near shore’ rescue needs. Specifically, VHF with DSC – digital select calling. DSC can function as a distress call AND beacon for the CG and any other vessel that receives DSC transmissions.

To keep it simple, hit the red button on your handheld VHF radio with DSC and within 20-mins the CG is there … if everything goes well. DSC distress is sent instantly (EPIRB data is NOT sent instantly) and includes GPS location data and time stamp. (Time stamp is important.) The CG gets that data immediately. Any boats in the area receiving DSC will immediate get the distress and may arrive b/4 the CG.

Hey, if you are kayaking out 25 or 50 miles off-shore in a submersion survival suit, an EPIRB is the way to go. But, realistically, most of us kayaking near shore in something comfy are going to have problems surviving 2-hrs in the No CA waters. From what I understand about EPIRB technology and how it works, I think of EPIRB on a near shore kayak not so much as being about ‘rescue’ as it is about ‘recovery’ … the recovery of a body.

I like ICOM products. There are others, do your research for VHF with DSC:

https://www.icomamerica.com/en/products/marine/handhelds/m94d/default.aspx

Did I mention it wasn’t going to be cheap? 

Do it right so that if the shit ever really does hits the fan you DO get back to your wife and your kids. 

That's great info Otis 

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs ...

I don't believe that is correct. As I understand it, there is an older version of EPIRB that uses satellites to determine location, and that can take up to 2 hours to get a fix on the location. However, modern EPIRBs (and PLBs) are GPS enabled, so they instantaneously provide location information. Of course, how long it takes for someone to actually arrive on scene will depend on how quickly that info gets to the Coast Guard and how close they are to you.

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs ...

I don't believe that is correct. As I understand it, there is an older version of EPIRB that uses satellites to determine location, and that can take up to 2 hours to get a fix on the location. However, modern EPIRBs (and PLBs) are GPS enabled, so they instantaneously provide location information. Of course, how long it takes for someone to actually arrive on scene will depend on how quickly that info gets to the Coast Guard and how close they are to you.

In addition, a 406 mHz EPIRB will also transmit a homing signal on 121.5 mHz for CG air and surface units to home in on your exact position once in the area.  The broader location early on in activation is fine because of this. 

ComCen verifying authenticity of a rescue

This isn't a thing that happens.  Every EPIRB activation is responded to.  I can't tell you how many evenings I spent walking up and down docks in marinas with the hot dog cooker trying to locate the accidentally activated EPIRB on some pleasure craft.

your handheld VHF radio with DSC and within 20-mins the CG is there

The USCG doesn't have magically faster boats just because DSC was activated versus EPIRB.  There is no game of telephone where people are handing off EPIRB activation messages.  The average 2 hour response you mention (which... citation needed) is due to the speed of vessels, the area covered by a single USCG station, etc.  But, it's a bit moot since the USCG readily activates the nearest resource, USCG or not.  For example, activating the HMB Harbor Patrol or the Coyote Point Harbor Master or the Alameda County Fire Marine Unit.

My question was “WHY” do you have and EPIRB?

Because I've been the rescuer and I've personally experienced the value of a PLB/EPIRB worn on someone's PFD and I've seen first hand how it resulted in a much faster rescue in nearshore conditions.

an epirb and plnb are two different things.. i think that's something that needs to be addressed as well... none of these guys are carrying epirbs on their yaks.  my epirb, on my boat, is the size of a big Gatorade bottle... nobody (yes big assumption) has this on their yak..

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs ...

I don't believe that is correct. As I understand it, there is an older version of EPIRB that uses satellites to determine location, and that can take up to 2 hours to get a fix on the location. However, modern EPIRBs (and PLBs) are GPS enabled, so they instantaneously provide location information. Of course, how long it takes for someone to actually arrive on scene will depend on how quickly that info gets to the Coast Guard and how close they are to you.

There is a hand-off delay at every stage – beginning with EPIRB activation and contact with the first sat system. Then a delay waiting for sat1 to pass by sat2 to hand off the data. Then a delay waiting for sat2 to pass by and hand off the data to the central command office. Then a delay with the central office verifying the authenticity of the EPIRB and a rescue need. Only when all of that happens is the ‘rescue’ handed off to SF CG. Then the time for CG to be on-sight. All of those delays add up to about 2-hrs … if things go well. Longer if they don’t.

It is possible you could spend upwards of 40-mins waiting for just the 1st sat (polar orbiting) to pass by. (Note: it is from my memory that sat passes by about every 40-mins so that delay time could be wrong.)

When an EPIRB/PLB activates it immediate send the unit ID. Doesn’t mean there is a sat there to receive it, but it is sent. Then it starts looking for sats to get a GPS location. They don't have constant GPS info as it would run down the batts. Subsequent broadcast will include GPS data with the unit ID. If GPS  is not available the Central office can extrapolate location by triangulating based on the start and stop contact times with the polar orbiting sat. The Cen office knows where the sats is when it picked up an active EPIRB. My understanding was it takes multiple passes from the sat to narrow down where the EPIRB is. With or without GPS data, the party starts when the first sat receives an EPIRB ID.

I believe it was something like less than 10-mins after getting a rescue notification the SF CG is airborne. They head out toward the sea with no known location to look at. As they go they start receiving the location data and make course corrections. There is no assumption the EPIRB is with those needing help. With an EPIRB they do not go to the location of activation. Central office estimates drift based on current, winds, and sea condition and sends updated locations to the rescue crew in the air. Depending on the time since EPIRB activation they start looking for you possibly miles from where the EPIRB was activated. If you are alive they can find you pretty quickly with thermo-imaging.

an epirb and plnb are two different things.. i think that's something that needs to be addressed as well... none of these guys are carrying epirbs on their yaks.  my epirb, on my boat, is the size of a big Gatorade bottle... nobody (yes big assumption) has this on their yak..

They both work the same way, same freq, same sat systems, they are both basically the same things … like having a mama version and a baby version. 

The diff is PLBs are for people, not boats, EPIRBs are for boats, not people. The size diff represents battery capacity and functions (e.g. strobe light, other stuff) required for an EPIRB to be used on a boat. PLBs are not “certified” for use on a boat, but most certainly can be used as such. PLBs are not required to float, lose that and all you have is a prayer your unit’s ID and GPS data was handed off to the sat before it sunk … presuming you got it activated before losing it. There is no confirmation the sat received the data.

yes, the big disctinction is that my epirb has my vessels info on it, my plb has MY info. not sure you can reg an epirb without a registered craft

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs ...

I don't believe that is correct. As I understand it, there is an older version of EPIRB that uses satellites to determine location, and that can take up to 2 hours to get a fix on the location. However, modern EPIRBs (and PLBs) are GPS enabled, so they instantaneously provide location information. Of course, how long it takes for someone to actually arrive on scene will depend on how quickly that info gets to the Coast Guard and how close they are to you.

There is a hand-off delay at every stage – ...

I think you are confusing non-GPS enabled with GPS-enabled devices. Here is a pretty good discussion (see, in particular, the section titled "Self-Contained GPS"):

https://boatwatch.org/safety-at-sea/new-gps-epirbs-and-plbs-explained/

The first few paragraphs are also relevant, where it talks about the importance of proper registration.

Several years ago when I was studying marine navigation I took it upon myself to calculate the absolute minimum rescue time using EPIRB for a vessel off the CA coast … just under 2-hrs ...

I don't believe that is correct. As I understand it, there is an older version of EPIRB that uses satellites to determine location, and that can take up to 2 hours to get a fix on the location. However, modern EPIRBs (and PLBs) are GPS enabled, so they instantaneously provide location information. Of course, how long it takes for someone to actually arrive on scene will depend on how quickly that info gets to the Coast Guard and how close they are to you.

There is a hand-off delay at every stage – ...

I think you are confusing non-GPS enabled with GPS-enabled devices. Here is a pretty good discussion (see, in particular, the section titled "Self-Contained GPS"):

https://boatwatch.org/safety-at-sea/new-gps-epirbs-and-plbs-explained/

The first few paragraphs are also relevant, where it talks about the importance of proper registration.

Thanks for the link, it is a good read, tho it has some errors. I don't think GPS has anything to do with how the system works but GPS location is data passed along with the EPIRB ID.

For an EPIRB signal to be picked up “instantly” there needs to be a Geo-stationary (“hovering”) sat just sitting there. The system did not work that way before, I doubt it does today, and the article eludes to that when talking about doing calculations when there is no GPS data – the article contradicts itself.

When I did my research, EPIRB system including TWO separate sat systems. The first sat system is polar orbiting, circling the Earth from top to bottom. This sat system picks up the 406 mhz frequency that is the EPIRB ID and GPS data, if any. I also understood without GPS data available, the polar orbiting sat could be used to triangulate a location but it would take multiple passes of sats to do that. From the article:

“Without GPS, polar-orbiting satellites compute an EPIRB’s position as they pass overhead, but this often takes 90 minutes and could exceed three hours …”

NOTE: there was no Geo-stationary sat system waiting for activated EPIRBs - they are polar orbiting sats and that means there is likely going to be a delay from the start. (Realistically, if the sat is passing overhead when an EPIRB is activated, there is no delay – if the sat has just passed by, it is about a 40-min delay until it returns.) The whole system has a delay at each step. That “delay” time will increase as ‘the rescue’ propagates through the system.

There is a delay (1st Delay) while waiting for the polar orbiting sat to come up from the South pole and pass by on it way to the North pole. That is when the EPIRB’s data enters the system.

Total time to rescue, so far = 1st Delay (getting the signal to the first sat – anything from 0 to 40 mins)

The second delay (2nd Delay) comes waiting for that polar orbiting sat to go up and over the North pole, and back down the other side, headed toward the South pole. On its way down the backside of the Earth, it passes over the equator. The second sat system is orbiting adjacent to the 1st sat system, going around the equator. As the two sats pass each other, the first sat heading for the South pole, hands off the EPIRB’s data to the second sat whipping along the equator.

Total time to rescue, so far = 1st Delay + 2nd Delay (handing off the signal from first sat to second sat)

The 3rd Delay is waiting for the second sat to complete enough of an orbit to pass by the command center, located in the US, and hand off the EPIRB’s data.

Total time to rescue, so far = 1st Delay + 2nd Delay + 3rd Delay (hand off the signal from second sat to command center)

There is an authentication and verification delay that is necessary and unavoidable (4th Delay) performed by the command center.

“… staff of that RCC attempts to verify the signal is intentional — 96 percent are false alarms.”

Total time to rescue, so far = 1st Delay + 2nd Delay + 3rd Delay + 4th Delay (command center authentication)

After the command center authenticates the need for a rescue, they hand off the info to SF CG. It takes time for the CG to get on-site. (5th Delay).

Total time to rescue = 1st Delay + 2nd Delay + 3rd Delay + 4th Delay + 5th Delay (time to get on-site)

When I did my calculations, years ago, the total of all of those delays came to just under 2-hrs. The lion’s share of the total delay was with 1st, 2nd, and 3rd Delays – waiting on sats to get to where they need to be. Maybe things have changed, maybe the system somehow works quicker now?!? Maybe there are more sats? Maybe the sats are moving faster? Maybe there is an entirely system in place?

To compare: VHF with DSC involves pushing the red button that sends a digital VHF distress signal (with GPS data) the SF CG is always monitoring. Total delay to start rescue is 1-millisecond, the whole rescue is starting at: … time for the CG to get on-site (5th Delay). The 5th Delay is the average time from notification to on-site for a rescue which I believe is 20-mins for SF CG.