PLB recommendations

[rpwillia]

Great discussion. I have had the OceanSignal flare for several years and their stuff is awesome. I also spent about an hour at the Annapolis boat show BS'ing with the rep and learned a lot about why things are the way they are. The PLB vs MOB debate is a good one. I did ask the rep why they did not combine them and there were a couple of issues so we are stuff with having to choose for now. My thought is that is you are in the Chesapeake Bay or a similar body get the PLB; if in the ocean you need the PLB. FWIW, I worked on an upgrade of the NOAA/NESDIS COSPAS/SARSAT system 16 years ago and DLochner has the process about nailed on how it works. It is not super fast or efficient but it will work; AIS will get the attention of every boat with in a couple of miles and with the USCG Rescue21 upgrade to their VHF communications they will most certainly hear it as well. Since both systems communications are digitally based and they repeat there is really no chance they will not get the message and your location. DrJudyBs testing of the radio confirms that relying on a handheld VHF in the water is likely to not work; especially when you consider VHF is line of sight and you and the radio are in the water.

 

[stephen_i_w]

Great discussion. I have had the OceanSignal flare for several years and their stuff is awesome. I also spent about an hour at the Annapolis boat show BS'ing with the rep and learned a lot about why things are the way they are. The PLB vs MOB debate is a good one. I did ask the rep why they did not combine them and there were a couple of issues so we are stuff with having to choose for now. My thought is that is you are in the Chesapeake Bay or a similar body get the PLB; if in the ocean you need the PLB. FWIW, I worked on an upgrade of the NOAA/NESDIS COSPAS/SARSAT system 16 years ago and DLochner has the process about nailed on how it works. It is not super fast or efficient but it will work; AIS will get the attention of every boat with in a couple of miles and with the USCG Rescue21 upgrade to their VHF communications they will most certainly hear it as well. Since both systems communications are digitally based and they repeat there is really no chance they will not get the message and your location. DrJudyBs testing of the radio confirms that relying on a handheld VHF in the water is likely to not work; especially when you consider VHF is line of sight and you and the radio are in the water.

Since AIS is transmitted at VHF frequencies, it has all the same range limitations as VHF. The MOB1 is also a portable device, with a transmitting power of 1 Watt (for AIS) according to the manual. This makes me wonder what the actual range will be for the MOB1 device, given that it would be transmitting close to the surface of the water and with a limited transmitting power. It would seem that a range of 5 miles would be very optimistic.

To quote from the manual for the MOB1:

"1.3 Warnings A Man Over Board AIS transmitter is only intended for short range signalling to an AIS receiver installed onboard your own vessel.

It will not directly alert the emergency services or any other vessels...

...This radio device is designed to only provide an effective alerting and locating capability in close proximity to a vessel. This radio beacon is NOT an EPIRB..."

I just cannot see how this device would help in my situation.

 

[Timm R Oday25]

As a fellow Great Lakes sailor ,I've followed this thread with great interest. Most of my sailing is done solo. The way I looked at it was this . There are 2 distinct types I would need to call for assistance . If I'm solo and I fall overboard ,I'm pretty much done for . Quite often I'm the only one out on the lake . Other boaters are usually barely visible . I highly doubt most would have even the slighest idea of someone who might be in trouble ,especially if they are already in the water
The other scenario that I can envision is our boat taking on water ,the mast coming down or someone needing serious medical help..It is at this time I would want the help of a trained proressional . I decided ,for my circumstances that the ACR Rescue Link with the gps coordinates disply was my best option . This is in addition to a well maintained DSC vhf radio.

 

[stephen_i_w]

As a fellow Great Lakes sailor ,I've followed this thread with great interest. Most of my sailing is done solo. The way I looked at it was this . There are 2 distinct types I would need to call for assistance . If I'm solo and I fall overboard ,I'm pretty much done for . Quite often I'm the only one out on the lake . Other boaters are usually barely visible . I highly doubt most would have even the slighest idea of someone who might be in trouble ,especially if they are already in the water
The other scenario that I can envision is our boat taking on water ,the mast coming down or someone needing serious medical help..It is at this time I would want the help of a trained proressional . I decided ,for my circumstances that the ACR Rescue Link with the gps coordinates disply was my best option . This is in addition to a well maintained DSC vhf radio.

Why do you like this particular unit over other PLB units such as the PLB1, Artex PLB, McMurdo Fast Find 220, etc?

 

[JohnShannon]

Since AIS is transmitted at VHF frequencies, it has all the same range limitations as VHF. The MOB1 is also a portable device, with a transmitting power of 1 Watt (for AIS) according to the manual. This makes me wonder what the actual range will be for the MOB1 device, given that it would be transmitting close to the surface of the water and with a limited transmitting power. It would seem that a range of 5 miles would be very optimistic.

To quote from the manual for the MOB1:

"1.3 Warnings A Man Over Board AIS transmitter is only intended for short range signalling to an AIS receiver installed onboard your own vessel.

It will not directly alert the emergency services or any other vessels...

...This radio device is designed to only provide an effective alerting and locating capability in close proximity to a vessel. This radio beacon is NOT an EPIRB..."

I just cannot see how this device would help in my situation.

Ouch, didn't realize this, so thanks I learned something. That makes this useless for single handers as the only boat that knows you are in the water is the boat with nobody on it. It seems you can manually initiate an "all ships" call which should inform others but dunno about figuring that out as you are freaked out, bobbing around in the water.

 

[jssailem]

VHF is line of sight. The CG get a boost in range because they locate their antenna on top of the highest bluff/mountain in the regional area. So on a flat sea you should have decent range. What will get in the way and cause an intermittent transmission is the 4 meter seas that transmit great when your on the crest but are the pits in the trough.

All of the nearby vessels usually, locate their antenna high on the boat/ship. This increases the range of the radio for transmission and reception. Your MOB1 will benefit from this structure. i know that my Antenna is up about 50ft above the water

Here is a quick calculator...
50 feet above the water gives me a range of 8.7 miles on a flat surface.

Radio Line of Sight Calculator for use on VHF/UHF Ham Bands

Learn how line of sight plays an important part in using Ham Radio on VHF/UHF frequencies with a calculator!

hamuniverse.com

Of note, If you are transmitting your mayday message from the water using your MOB1. And I get it at the maximum range, you are likely to be dead from hypothermia by the time I get there. (Best case 60 minutes unprotected in Pacific NW Water). Be assured I will make every effort to get there as fast as possible.

 

[Timm R Oday25]

Several reasons ,the coordinates being displayed was of significant importance to me . ACR has an excellant reputation amoung professional mariners . I'm fortunate to be aboard several professionally skippered boats a couple times a year. Most of these boats hace ACR equipment on board . The unit itself is small enough for me to easily take it from boat to boat . This was one of the very few purchases I've made where cost was not a consideration . Even so ,I thought it was reasonably priced at just under $400.00 I think

 

[stephen_i_w]

Fortunately in late summer the water in Lake Huron is not as cold as Puget Sound. Unfortunately, having line of sight does not guaranty successful communication. Many other factors can interfere with radio propagation. It is true, however, that digital signals will be readable in poorer conditions than voice. I will repeat what I quoted before from the MOB1 manual:

"1.3 Warnings A Man Over Board AIS transmitter is only intended for short range signaling to an AIS receiver installed onboard your own vessel."

It seems prudent to take them at their word.