OK - so why cant you listen to the MSB BEFORE going afloat? Thats kind of the idea. Not a lot of point in being out and being told its about to blow a hooolley?
Herne Bay is in the Thames operational area.
Thames should transmit an MSB on: CH 23, 84 or 86 at: 0110, 0410, 0710, 1010, 1310, 1610, 1910, 2210 (Local Time)
They will announce on CH16 immediately before hand unless they are working something significant on 16. Channel depends on the aerial you are nearest. Don't know the geography down there well enough:
Walton, Shoeburyness, Southend – 23;
Fairlight, Bawdsey – 84;
Bradwell, Langdon – 86
If you are on DSC you can call them on: MMSI 002320009 (Guess as you are on a SIB you are on a HH so probably not)
So I'd turn up at the launch site at 10am. Stick the VHF on while sorting things out ashore...
Have you looked at tides?
Why would u think of putting your boat in the water without knowing whats under that water. Get a F***in Chart!