Lifebuoys on board the s.b. Hydrogen, another one of the fleet of preserved Thames barges on the River Blackwater at Maldon, Essex.
More information on her here and at the National Historic Ships website, which latter site states that Hydrogen was:
“Built of pitch pine on oak in 1906 by John Gill & Sons of Rochester, HYDROGEN was a large boomie (gaff ketch) rigged coasting barge capable of carrying 200 tons of cargo. Her owners were Burt, Boulton and Heywood, chemical manufacturers of Silvertown, and she was one of three similar barges built for them by Gills: Carbon, Oxygen and the last of the trio, HYDROGEN, all named after the elements that make up oil.”
Patrick Mackie 