A fire damaged four boats and caused nearly £50,000 of damage in Teddington Lock last week.
London Fire Brigade, Richmond Police and Teddington Royal National Lifeboat Institution attended the scene on Wednesday
26 March after a passerby called 999 at 1.32am.
The fire was under control by 4am, but caused damage of up to £45,000 sinking two boats with two more badly damaged.
The fire began on three boats moored downstream from the lock, two of which untethered and floated upstream into the lock. Firefighters were tackling the flames when RNLI volunteers arrived.
RNLI volunteer Samantha Armitage said: “The scene was dramatic. There was a loud explosion after the second RNLI boat was launched.”
RNLI discovered a boat alight upstream from the lock.
Jon Chapman, RNLI helm, said: “We were able to play a useful part, locating the third fire before it became a major risk.”
On Monday night, CCTV caught two suspects attempting to break into a
There is no evidence linking these incidents, but suspicious behaviour in the area has led to police appeals for information.