Reports of Speed limit reductions on the River Thames

According to the Evening Standard and the BBC, they report that the Port of London Authority (PLA) have halved the speed limit on the River Thames from 24 to 12 knots.

This has had the effect of doubling the commute from Greenland Dock to Embankment from 20 minutes at rush hour to 40 minutes.

The ostensible reason? Well the PLA claim to have made it as a ‘precautionary’ measure because of a significant increase in the number of fast vessels that use the Thames.

They are reported as saying: "In recent months new vessels have started operating new services on new routes and leisure operators have introduced tourist-related high-speed trips.

"This measure will help ensure continued high safety standards on the river."

I had understood that what limits there are were applied upstream (west) of Wandsworth Bridge, 4.3 knots (8kph) in the non tidal section and 8 knots in the tidal section of the river - and that downstream (east) of this point, the only requirement was that boats were not allowed to create ‘undue wash’.

Apart from that, what doesn’t quite scan, when you think about it, is the fact that if there was a previous 24 knot limit then surely none of the boats would have exceeded it.

If they had, then logically they could have been prosecuted. What difference does it make what speed they happen to be capable of travelling at, provided they only actually travelled at 24 knots?

If they couldn’t have been prosecuted then what is to hold them to any lower limit?

As for the number of boats – the numbers using the Thames now are nothing in comparison to those of the first half of the 20th century. The river is not exactly crowded.