All
In my honest opinion the lower Thames between woolwich and southend is a pretty boring stretch of river that just eats up fuel, your far better off doing the stretch between woolwich to putney and then doing a second day exploring of the east kent coast from Whitstable or Herne bay, from Herne bay its possible to get out to the world war 2 sea forts in the estuary, down to the surface visable wreck of the Montgomery and down as far as the M2 road bridge on the Medway and back around the inside of the isle of sheppy in one tidal window, approx 120 nautical miles.
As an alternative turn right out of the end of Herne bay harbour and go around to Ramsgate or Folkestone , passing margate, Birchington and joss bay and back to Herne bay.
Next time you guys come south and want to do something other than the Solent give me a shout.