✹ About Friday 4 August 1665 RSGII on 5 Aug 2018 • Link Thames tides. I don’t have local knowledge, but the published tide tables and current flows in the Thames below the modern London Bridge are quite formidable. Tides can have a maximum range of 25 feet and river velocities can vary from 2 to 7 knots, very difficult for a human propelled craft to handle. Of course the modern river has been substantially altered with embankments etc. so hard to know with any precision what the numbers were in Sams day. But may explain why those royal barges need so many rowers!