I always see huge boats arriving to the port of my city, huge, black and red, full of GASOLINE boats.
And I let my imagination do the work. I imaging one of those huge boats with a gasoline contaner and a kinf of freezer for food, and that opens a sort of door leting out a small ferry with armored vehicles like a hummer or a sport car with high suspension. The ferry would land on a port or beach letting a super trained team of shooters to look for gas, food, water,cars( for replacing the bad parts of the cars) and ammo.
And like that surviving,and looking for survivor and a HUGE second boat with similar characteristics ( maybe one for gas and the second for suplies).
Any survivor that looks to the sea will know that there 2 gigant boats that doesn`t were before.
And a non-realistic posibility of instaling a windmill in one boat for electricity.
I think that broadcasting in the sea is very good, so better for the radios.