[5] Larger ships, in fact, could not go beyond Wusong (at the mouth of the Yangtze) and Hankou (and moreover, for economic reasons, the Regia Marina could not afford to maintain warships on station in the Far East: for years the protection of the Italian communities was entrusted to the French[6]).
[5] The second gunboat (designed in 1913[6]) would be smaller than Sebastiano Caboto (247 t (243 long tons) of standard displacement[2] and 84–91 cm (2.76–2.99 ft)[7] of draft; also the freeboard was visibly reduced[8]) in order to be able to go upstream of the rivers more easily and safely, overcoming currents and shallows where Sebastiano Caboto had had problems (especially on the upper course of the Yangtze, characterized by strong currents in the final stretch [9]).
[5] The new ship was named after the sottotenente di vascello (sub-lieutenant) Ermanno Carlotto who fell during the Boxer Rebellion and was decorated with the Gold Medal of Military Valour.
[5][citation needed][13] The gunboat was commissioned in March 1921[14](other sources, however, place the entry into service on 12 December 1921[6]) and was immediately sent to the Hai river, where conflicts between two Chinese warlords were endangering foreign citizens.
[4][5] In 1923 the gunboat Carlotto has successfully sailed upstream of the Yangtze for over 1,000 miles (never successfully attempted until then) under the command of 1° tenente di vascello (first lieutenant) Alberto Da Zara (the only other two ship officers were the chief engineer, tenente (lieutenant) of the Corps of Naval Engineering Felice Fantin, and the doctor, sottotenente di vascello (sub-lieutenant) Neilson Gerardo Montgomerie[6]):[9] this voyage took the ship where no other unit had hitherto gone, reaching the altitude 200 m (656 ft) above than the starting one (which was at the sea level).
[9] Passing at low speed near Shin Men over dangerous rocks (where less than two years earlier the French gunboat Doudart De Lagrée ran aground, reporting serious damage), Carlotto approached the rapid of Yeh-T'an, 500–600 m (1,640–1,969 ft) in length with the shape of an isosceles triangle (with the base upstream and the vertex opposite towards the valley), which also proved to be very difficult to negotiate for the previous ships that had tried to pass it (the Royal Navy gunboat HMS Kinsha had given up after three unsuccessful attempts, while the French Olry had only managed to overcome it by being towed from the ground).
Da Zara sent all the crew to their posts and told the engine room to keep ready to develop the maximum speed, then maneuvered to approach the right bank, trying to avoid ending up in the countercurrent (which would have run aground or capsized the ship):[6] the Italian gunboat, vibrating and rolling strongly due to the continuous eddies that formed at the bow and at the sides, and approaching continuously to keep to the edges of the counter-currents and in the center of the bed, overcame the rapid proceeding very slowly (at 2–3 kn (2–3 mph; 4–6 km/h), although the ship was pushing at the maximum speed of 13–14 kn (15–16 mph; 24–26 km/h)[15] and the wind called Shang Feng blew the stern against the waves that hit the bow), concluding the maneuver in 22 minutes.
[6][9][11][15] The ship, however, continued and on 25 June arrived in Yibin, where the Upper Yangtze began, and she stopped there briefly for some repair work, after which she entered the river Min.
The enterprise had great public resonance, and the Grand Admiral Paolo Thaon di Revel, Minister of the Navy, praised the commander Da Zara, the officers and all crew, especially the engineers.