Scale: 1:48. The original design for Lobnitz rock breakers was patented in the late 19th century, and it was very successful with over 100 vessels supplied to contractors all over the world. Colonel George W. Goethals, chief engineer of the Panama Canal project, used a Lobnitz rock breaker as it proved to be cheaper and more effective than the alternative method of rock blasting by explosives. The cutters weigh between 6 and 22 tons and their special steel points penetrate the hardest rock. The Lobnitz patent underwater guide, in the form of a vertical tube enables the rock-breakers to work to depths of about 20 metres.

The model depicts two rock-breakers (1922) built by Lobnitz & Co., Renfrew, Scotland, for the Tilbury Contracting and Dredging Co. Ltd. We can see what practical vessels they were with their flat-bottomed barge-like hulls, rock-breaking apparatus mounted at the stern and with their power plant at the extreme bow end to act as a counterbalance. It is a handsome model with its rectilinear lines and tall, vertical stack with the characteristic red and yellow colours of the vessels’ owners. The warning sign 'Please Slow Down' is mounted on the decking.