I clip a handheld VHF on my waistband. It’s the waterproof, floating Icom M93D with built-in GPS and DSC. A red button on the back lets you send a DSC distress call to rescue agencies, as well as nearby boats with DSC-equipped VHFs, with your GPS coordinates. And, of course, you can transmit a mayday by voice and converse with rescuers. In order for DSC to function properly, you must register for a Maritime Mobile Service Identity (MMSI) number and enter the information into the VHF. If you already have an MMSI for your boat’s fixed-mount VHF, you can use it for the handheld too.