- Doxford 580 JS 3 engine
This series of ships were the only ones fitted with the Doxford 580JS3 engines, the uncommissioned one is the preserved engine at Beamish Regional Museum Store.
Many of the the components used on these engines were those deigned for the Doxford Seahorse engine. Only a prototype of the joint Doxford, Hawthorn Leslie (hence Seahorse, after Hawthorns house flag), four cylinder, medium speed engine was built and was scrapped after five years. The three cylinder 580 JS engines were slow speed. 580mm bore, J after Jackson the man responsible for the design of the original Doxford J engine, and S for short piston stroke.