I have used an ( emergency position indicating radio beacon) EPIRB, Wayne.
This reply to your question may or may not be of use to you as like all technology the EPIRBS and similar kit have shrunk in size and weight and probably gained much in effectiveness since I used mine in 2007.
I was making single handed ocean voyages at the time and the McMurdo beacon I had operated on both the 406 and 121.5 MHz frequencies. At that time 406 was the International standard for Epirbs while 121.5 was more a land based and localized system, although commercial aircraft would pick up the signal mid Atlantic when passing overhead, and 121.5 was received by many stations and satellites orbiting the developed regions of the World, the 406 MHZ signal operated reliably basically everywhere.
In view of the above...if...the systems are still basically the same, then for your purposes a beacon operating on 121.5 will be sufficient. If you are going High Arctic, personally I would go for a dual frequency..such as ...
https://www.mailspeedmarine.com/mcmurdo-fastfind-220-plb.html
I got caught single handed voyaging to Florida in early May 2007. I had crossed from the Canary Islands and spent a few months wandering the Leeward Islands and then sailed for Miami before the Hurricane season set in...I thought!! Sub Tropical Storm Andrea had other ideas and appeared a few weeks early....
One thing you may consider doing if you purchase a Beacon is to contact the monitoring authority and give them an approximate itinerary of your travels. I contacted Falmouth Coastguard, who are responsible for co-ordinating world wide rescues on 406MHZ, and told them I was sailing from the Canaries late December for the Caribbean, roughly where I was going, Antigua, St Kitts, Dominica etc: and that I would be on passage for Florida in early May.
This forward planning worked a treat because when I stuffed my boat on a reef in seas the size of Buckingham Palace, having triggered the Epirb, Falmouth Coastguard got the signal, pressed a key on a computer and there was Wicca's message, so they knew it was not one of thousands of false alarms ( Many Doughnuts actually press the red button " to see if it works...
) It drives the poor Coastguard potty...
Falmouth Coastguard telephoned the US Coastguard in San Juan, Puerto Rico and asked them to fish me off the reef with one of their big helicopters.
I was in the water and scrabbling around on the reef for about 45 minutes from pressing the red button, so the rescue pilot told me, so the itinerary really was a life saver as I don't think I could have swallowed any more sea water and sand and I was running out of skin to leave on the reef anyway...
If you are going far places, an Epirb is certainly worth considering...I imagine the devices have become much more sophisticated since 2007, much lighter and cheaper at least.
