The most successful minelaying submarine of the war, Rubis was
responsible in her 22 minelaying patrols for the sinking of at least 15
vessels. These included five warships as well as vessels running iron ore in
coastal convoys to Germany.
Like the Royal Navy, the French had a six-strong class of
minelaying submarines, the 'Saphir' class of 1925-9. These were much smaller
than the British boats, being geared to Mediterranean operations. Again, as a
mine capable of being launched through a standard torpedo tube had not been
developed, the hull design was dominated by the mine stowage. The design for
this had been produced by the well-known submarine builder, Normand, but was
based on that of the British 'E' class minelayers of 1914-8: 16 vertical chutes
were built into the space between the widely-separated double hulls, in four
groups of four, and each chute could accommodate two mines, though a weakness
of the arrangement was that these were of special manufacture. The British had
abandoned the system in favour of laying over the stern with the mines stowed
within the upper casing.
Four stretched versions, continuing the 'jewel' names as the
'Emeraude' class, were scheduled to follow in 1937-8. Lengthened by nearly 7m
(22.97 ft), they would have carried 25 per cent more mines, but only the
nameship was ever laid down and she was destroyed on the slip at the occupation.
Of the 'Saphirs', three (Nautilus, Saphir and Turquoise)
were taken by the enemy at Bizerta and one (Le Diamant) was scuttled at Toulon.
The Rubis and Perle operated for the duration of the war (the latter was sunk
in error by British aircraft in July 1944) under the Free French flag. The
Rubis began operating with the British Home Fleet in April 1940, laying mines
in Norwegian waters. Between then and the end of 1944 she carried out no less
than 22 successful minelaying operations, most to interrupt the enemy's
coast-hugging mercantile routes. The total of 15 ships known to have been
destroyed on her mines included several Scandinavians carrying German ore
cargoes, a minesweeper and four small anti-submarine vessels. She also
torpedoed and sank one more, a Finn.
Specification
'Saphir' class
Displacement: 761 tons surfaced and 925 tons submerged
Dimensions: length 65.90 m (216.21 ft); beam 12 m(23.36 ft);
draught 4,30 m(14.11ft)
Propulsion: two diesels delivering 969.4 kW (1,300 bhp) and
two electric motors delivering 820.3 kW ( 1,100 hp) to two shafts
Speed: 12 kts surfaced and 9 kts submerged
Endurance: 12970 km (8,059 miles) at 7.5 kts surfaced and
148 km (92 miles) at 4 kts submerged
Armament: one 75-mm (2.95-in) gun, three 550-mm (21.65-in)
torpedo tubes (two bow and one stern), two 400-mm (15.75-in) torpedo tubes in a
tramable mounting, and 32 mines
Complement: 42