Before wherries, there was the Norfolk Keel, a square rigged, transom sterned clinker-built boat, 54 feet by 14 feet, and able to carry 30 tons of goods. The keel had been built since the Middle Ages and the design probably went back to the Viking invasion. After 1800, the Norfolk Keel (or 'keel wherry') disappeared, partly because a wherry could be sailed with fewer crew, and it had limited manoeuvrability and lacked speed.
Wherries came in different sizes, according to the river they used. The North Walsham & Dilham Canal Wherry was max. 50' x 12' x 3'6". The River Ant Wherry was 50' x 12' max. The River Bure Wherry was 54'x 12' 8", but for the Aylsham Navigation, i.e. the upper reaches of the Bure, the boats had to be 12' 6" x 3'6" maximum.
On the southern Broads, steam wherries were used. The River Waveney Wherry was 70' x 16' max.
Wherries could be propelled by hand, if need be, by using a quant pole.
A special wherry wheelbarrow was used to unload cargo, e.g. stone, from the wherries. It was made from wood and strengthened with iron bands. It had no legs, therefore it could be rested on the 11 inches wide planks on the side of the wherry.
A number of wherries have been restored and can be seen sailing up and down the rivers and broads - see: Wherry Albion, Wherry Maud, Wherry Solace, Wherry Hathor, Wherry Olive, Wherry Norada, Wherry White Moth, Wherry Ardea.