If you go offshore as an individual on a private boat, there is one electronic device that will give the highest probability that you will be found if you end up in the water or with no other form of communications. That device is called the Personal Locator Beacon.
This device costs in the range of $350 and is about the size of a hand held walkie talkie radio. It works with stalite communication and has a battery life of 5 years. You need to register it with your local water or oceanic agency, so that it is attached to you or your vessel and identifies you. This device is intended to be used in the extreme emergency where you are in the water and there is no other means of communications and this is your last resort of survival. It is a water resistant/proof device that is quick and easy to activate and sends out a distress signal with your coordintes. Use of this device is reported to have response times within 30 minutes of activation and a majority of the users have been saved and have survived. In conjunction with this device it is critical to have the proper Type 1 life vest as well as the proper devices for visibility such as water dye or beacon light probe for night time visibity if a helicopter was trying to locate you from the air.
The ACR is a one time purchase with no annual dues or subscriptions although they do have some models that have some advanced features you can pay annual services for like texting, but are not necessary features for the basic functions of being found. The basic ACR is what I own myself. Other brands do require annual subscriptions and may not be water resistant, so do your research... Another device similar to a PLB is a EPIRB, but you can research that up.
It is my recommendation that any person who decides to go out on a private vessel, that they invest in a PLB for their own personl safety and assurance. Your life is your responsibility and if you decide to take a venture on a vessle you do not personally own and maintain, take every measure you can to ensure your own safety with whatever means available to you. In my recommendation, this is at the top of the list.
I will ALWAYS recommend everyone to take and complete the boaters license course even if you do not own a boat. It's simply a course that provides you a solid education on boating in general. It's very cheap to do, it's easy to do (my son completed this by himself at age 12) and it will be with you for the rest of your life!