A lot of people assume that hitting the
EPIRB emergency button is a "Get Out Of Jail Free" type of automatic rescue. While off the coastlines of the USA the chances of initiating a rescue attempt are good I consider my
EPIRB more of a "tell mum I won't be coming home" signal. That having been said, one never knows when one might get lucky in a disastrous situation and get rescued from the
liferaft after setting of the beacon; but one of my premises when going offshore is that I've got to rely on myself and not on any outside assistance.
The DSC capable
radio will send out a digital MAYDAY with accompanying digital
GPS coordinates in the message. This will only go out to DSC
radios (which commercial ships have) and it won't get lost if the operator happens to be on elsewhere when the emergency signal gets sent out - it triggers a very loud alarm on all DSC equipped
radios and needs to be shut off manually. Unfortunately the standard limitations of
VHF comunications apply and the other ship will have to be relatively close - plus your antenna still needs to be attached to the boat.
The tethers & jacklines are a given for any boat and any budget so we should just taken those out of the list.
I believe that $700 of disposable income when deciding between an AIS transceiver and an
EPIRB is a difficult decision. If your boat has lots of crew that are watchstanders then AIS is less of a safety matter and an
EPIRB is a better choice. With less crew an AIS transmitter/receiver will help avoid going "bump" in the night against commercial vessel.
It is difficult to argue about safety and the value of life in terms of dollars; but there is always a point where additional items of safety insurance need to stop, otherwise one would need a bigger boat to hold everything - start with flares, inflatable
lifevests, jacklines, portable VHF, ISAF Flares / flaregun,
liferaft, emergency hand-powered watermaker, additional VHF, EPIRB, personal SART,
SSB, AIS, the list just goes on and on (i.e. spare VHF antenna for dismasting, extra VHF in grab-bags, etc.).