This was from the skipper on YBW, pretty poor excuse as bugger all to hit out at sea and regardless of where you are you should be in control at all times and not be at the mercy of the wind or water flow, a lesson I learnt on my first boat handling lesson when I destroyed my guard real on a bow roller.
I am very experienced but mostly at sea, but not so with dealing with a rivers tidal flows.
The yacht makes 5 Kts over SOG with both engines in gear, though from Teddington to Richmond the boats port or stbd engines were only engaged, fwd and astern, to keep her positioned.
The necessary tidal height calculations were completed and a phone call to the PLA boys in the area informed me that I should expect and increase of half a metre on listed tidal heights, this was also taken into consideration. As you could see once I had extracted myself from the bridge I squeezed through as with enough headway backing up my initial precaluculations.
The problem I encountered was aligning the yacht up to the centre line of the arch as the arch has rather steep drop offs from the centre line. Once astern thrust had been engaged, the strong tidal flow started to push the stern to the starboard rather rapidly. This caught me unawares as the yacht obviously has a lot of power to hand, but not enough to stem the tide.
I've certainly learnt a harsh lesson in coping with strong tidal currents, and narrow bridge arches."