Commissioned in , she served during World War I and was stricken in They had an overall length of Their crew numbered two officers and 23 enlisted men. For surface running, the submarines were powered by two metric-horsepower bhp ; kW triple-expansion steam engines , each driving one propeller shaft using steam provided by two Du Temple boilers.
When submerged, each propeller was driven by a metric-horsepower bhp; kW electric motor. The first six submarines completed were armed with a single millimeter All of the submarines were fitted with six millimeter Following a ministerial order on 22 February , the aft tubes were reversed so they too fired forward, but at an angle of eight degrees.
The other launchers were a rotating pair of Drzewiecki drop collars in a single mount positioned on top of the hull at the stern. They could traverse degrees to each side of the submarine.
Watt , named after the British 18th-century inventor James Watt , was ordered on either 26 August [ 6 ] or 19 October [ 7 ] according to different sources from the Arsenal de Rochefort in Rochefort , France.
During her builder's sea trials , she suffered steam engine damage on 21 December that forced her to interrupt her trials and return to port. Watt was completed in Watt struck either a breakwater , jetty , mole , or seawall as she returned to her anchorage on 3 December She suffered bow damage with an estimated repair time of two months.
