NAVYPEDIA

Ships

Name	No	Yard No	Builder	Laid down	Launched	Comp	Fate
S1	I04		Scotts, Greenock	8/1912	28.2.1914	8/1914	to Italy 10.1915 (S1)
S2	I0A		Scotts, Greenock	10/1913	14.4.1915	5/1915	to Italy 10.1915 (S2)
S3	I1A		Scotts, Greenock	3/1914	10.6.1915	9/1915	to Italy 10.1915 (S3)

Technical data

Displacement standard, t
Displacement normal, t	265 / 324
Length, m	45.1
Breadth, m	4.40
Draught, m	3.16
No of shafts	2
Machinery	2 6-cyl Scott-FIAT diesels / 2 electric motors
Power, h. p.	650 / 400
Max speed, kts	13 / 8.5
Fuel, t	diesel oil
Endurance, nm(kts)	1600(8.5) /
Armament	2 - 450 TT (bow, 4)
Complement	18
Diving depth operational, m	30

Project history

In August 1911 a group of Admiralty officers visited FIAT-San Giorgio's works at La Spezia, and were shown the Velilla and Medusa. A month later, Scott's of Greenock, who had been FIAT-San Giorgio's UK licensees since 1909, offered to build a similar boat for £50,000. The tender was accepted that month and S1 was ordered. She was comparable to the 'C' class in size, and had the same armament, 2 450mm TT and 4 torpedoes. Although slightly slower she had a high reserve of buoyancy and a ship-shape form. The main disadvantage was the length of time taken to dive, an inherent problem with the Laurenti type of double-hull construction. Although some sources suggest that the 'S' boats were not sufficiently seaworthy for North Sea operations there is no apparent reason why boats with such a high reserve of buoyancy should be poor seaboats; a more likely reason is the general lack of familiarity with Italian practice and equipment.

The design followed Laurenti's principles, with a partial double hull and a wide 'duck tail' stern. There were no fewer than ten watertight bulkheads, at a time when the 'E' class had only two. Two more boats were ordered in June 1913.

Modernizations

None.

Naval service

All three were transferred to the Italian Navy in 1915 as the RN had more submarines than it could find crews for. They served under the same numbers in Italian service.