Once you purchased your VHF marine radio, don't forget to program DSC function on it that allows you to instantly send formatted distress alerts to the Coast Guard.
You should get familiar with the procedures of making distress calls. Below is an example of an emergency call using VHF marine radio.
Stay by the radio if possible. Even after the message has been received, the Coast Guard can find you more quickly if you can transmit a signal on which a rescue boat or aircraft can home.