Bertha has a tonnage of 60 and is constructed of riveted iron with a timber superstructure.
The steam engine is a single cylinder double action engine and operates at a pressure of 40 pounds per square inch, steam is raised in a coal fired boiler of unknown vintage, the motion is transferred to the main drive shaft which can be recognised by the large flywheel by means of a single reduction spur wheel drive.
Sometimes mistakingly referred to as a dredger, Bertha is in fact a drag boat. Where as a dredger operates by lifting the mud and silt out of the water, a drag boat is rather like a floating bulldozer with a submerged blade which scrapes the material along the bottom.
Although steam powered Bertha has neither screw propellor nor paddle wheels but is moved by hauling herself along a chain, the ends of which are secured to quayside bollards.
Bertha is believed to have been designed by the eminent victorian engineer Isambard Kingdom Brunel and has the destincition of being the oldest operational steam driven vessel in Britain – possibly the world.
Bertha was probably designed in Bristol and assembled in Bridgewater where her role was to keep the docks clear of mud and silt. To do this, the blade, mounted on a sliding pole, was lowered by means of a chain. The vessel then hauled herself along the main chain bringing with it the mud and silt which was dragged out into the river Parrett where it was carried away by the tide. The vessel then hauled herself back along a lighter chain and the procedure repeated.
July 5th, 2008, 9:10pm I was interested to see that Bertha still exists. I was aware that she was in Exeter and I believe Bristol for some time but was surprised that she is now in Eyemouth.
As a boy I can well remember watching Bertha operating in Bridgwater docks (Circa 1955). She always seemed to be working in the large inner basin moving mud down to the lock gate, presumably to be flushed out at low water. The big adventure was to go on board when the dock keeper wasn’t looking.
In those days Bridgwater docks were still just active. Coal being brought into the outer basin and mainly sand and timber in the inner Basin.
Good memories, perhaps if I am ever in the area I will come and visit to get reunited! John Lee
- Boat Name: Bertha
- Boat Use: Dredging
- Boat Type: Drag Boat
- Build Date: 1844
- Country of Origin: United Kingdom
- Area of Origin: Bristol/Bridgewater
- Boat Dimensions: Length 49 ft 3 in