Dan
Contributor
I have quite a few signalling devices but certainly less than @Dan_T. I now don't really think about getting more signalling devices but do think along different lines:
1. I think of upgrading what I have. As an example, my existing SMB will be replaced with a SOLAS SMB or a radar reflecting SMB. And, instead of eventually replacing the battery in my existing PLB that is rated for 24+Hrs, I'd be looking for a PLB that is rated for 36Hrs.
2. I also think of ways to deploy my signalling devices more effectively. My two radio beacons have operational limits of 24+Hrs for continuous transmission. To me, there is no need for continuous transmission, so I'm thinking of how best to deploy them intermittantly in order to extend their deployment window beyond 24Hrs. For the MRG, I'm thinking of activating it immediately for 20mins than switching it off for 1Hr and repeating. Assuming that I am drifting at 5 nautical miles per hour, I will have sequential MRG circular broadcast footprints that are 5 nautical miles apart at the centre and should be just as effective as having it broadcast continuously. However, I'd be extending transmission from 24Hrs to 96Hrs. I'm thinking along similar lines (intermittant transmission) for the PLB. SAR should have been alerted by the boat or resort that I'd diving with as part of the lost diver protocol, so there should be no need to activate the PLB immediately in order to tell SAR that I am lost at sea. I'd probably activate the PLB after 6Hrs, which immediate extends its transmission window by 6Hrs from the start of the situation. SAR will probably not get to me within 6Hrs anyway if I am are diving remote 3rd world countries. Once the PLB is activated, SAR will have my present coordinates as well as my initial coordinates from the dive boat/resort and can plot a reasonably accurate intercept for my drift direction and speed. Activating the PLB for 20mins then deactivating it for the next hour extends its useful life to 96Hrs, which in addition to 6Hrs for the initial delay in transmission, gives a total of 102Hrs. By activating the PLB intermittantly (20mins on then 60mins off), SAR has a continual plot of my drift to help them narrow the search area. These radio beacons give GPS coordinates, which should be highly accurate so SAR should get to me once I have started activating them.
3. I think of how to survive longer should SAR be a little slow. By using my two radio beacons intermittantly, I can extend the useful transmission window to in excess of 96Hrs. The survival guideline is 3 days(72Hrs) without water. This is the limiting factor that I have to address. Given limited carrying capacity, I'd prioritise some water over more signalling devices.
I’m not sure about cycling the distress alert signal to ON for 20 minutes & OFF for 1 hour for MRG / PLB would extend their battery life to 3 times. You would basically turning them on / off 18-19 times in 24 hours. Every time you activate them, it takes more energy to start up the transmission & obtaining a GPS fix than during the steady transmission. Like an airplane, it takes more energy during take off than during cruising. You gave better mileage per gallon driving in highway than in city traffic.
To activate PLB1, after pressing the ON key, the green LED light will flash once during 5 seconds while GPS is turned on and obtaining a fix. Once the fix is obtained, the green LED will flash quickly 3 times. Afterwards repeating alert sequence of 406 & 121.5 MHz transmission begins. I would imagine by repeating this PLB1 activation 18-19 times a day would not last my PLB1 battery life to 3 days.
Besides wasting the activation energy, you would be alerting the SAR Rescue Center every time you activate the PLB and the repetition of 18-19 activations / day might be received as false alert. Apparently PLB false alert transmission is pretty common to the point of NOAA posting a webpage to educate PLB owners on how to avoid sending false alert, NOAA - Search and Rescue Satellite Aided Tracking - Prevent False Alerts
“The following are some suggestions on how you (yes, you) can prevent false alerts. By doing so, you will increase the effectiveness of the very system your life may someday rely on! We can not stress the importance of this enough. Responding to the false alerts can cause large delays in responding to real emergencies. Unnecessary deployments also put the lives of search and rescue personnel at risk. Although Cospas-Sarsat is a high-tech, automated system, large volumes of false alerts can cost valuable minutes to people in real distress. Every little bit does help! So please, read the recommendations below and follow them. Above all, use common sense.
FOR PLB’s:
- Always test your PLB in strict accordance with manufacturers’ recommendations. Most PLB activation switches have a test position. This test position allows the entire unit (electronics, battery and antenna) to be tested without generating a false alert.
- Ensure that your beacon is registered with NOAA. This does nothing to reduce false alert rates, but does have a dramatic effect on the impact of a false alert. If the PLB is properly registered, the situation will be resolved with a phone call most of the time. It will also help speed rescue in an actual distress. It's free, easy, and it's the law, so please register all of your beacons.
- Maintain your PLB. Ensure that the batteries are within their expiration date and that all manufacturer recommendations are followed.”
MRG battery life may not be a problem. According to Ryan of Nautilus Lifeline, the batteriy should last quite a bit longer than one day. Assuming a full battery, the Nautilus GPS can continue transmitting the distress signal up to 80-90 hours. I do have spare CR123 Lithium batteries in my waterproof safety kit pouch anyway.
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