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Fast screw frigate (650 nhp)

ISLY (launched 1849)


ISLY fast screw frigate

Displacement:	2675t
Dimensions:	229ft 8in wl (238ft 2in to rudderpost), 240ft 10in deck x 42ft 8in mld, 43ft 5in ext x 19ft 4in mean
Same, meters:	70.00 (72.60), 73.40 x 13.00, 13.24 x 5.90m
Machinery:	650nhp (Cavé). First set: 4 oscillating cylinders, geared. Second set: 4 fixed cylinders, direct, 1530ihp, trials 12.4kts (reached over 13kts).
Hull material:	Wood
Armament:	(1845) GD 16-22cm No.1, 8 "larger guns"; SD 4-50p. (1850) GD 8-30p No.1, 8-22cm No.1 shell; SD 4-30p No.1. (1855) GD 12-36p, 12-22cm No.1 shell; SD 8-36p, 2-22cm No.1 shell. (1861) 12-30p No.1, 16-16cm rifles. (1869) GD 18-16cm rifles; SD 4-16cm rifles, 2-22cm shell.
Complement:	415

Name	Builder	Laid down	Launched	Commiss.	Fate
ISLY	Brest	26.8.46	19.7.49	5.10.50	Stk. 22.7.72

Class. This ship was the screw counterpart of Mogador, in which new technology such as tubular boilers was exploited to increase the horsepower of large steam frigates from 450nhp to 650nhp. She was briefly listed as Monge when first planned in 10.45 but had become Isly by 12.45. Plans for her hull by Lebas were approved in 7.46, her hull was ordered 7.8.46, and her first set of machinery was ordered 21.6.47. Because of her full steam power, she was to have received a light rig with square sails on the foremast only, but in 1851 the rig was increased. Her sail area was 2276 sq.yd. Her machinery proved to be structurally weak and was rejected after lengthy trials in 1851. The ship was decommissioned at Toulon in May 1852, and in 4.53 Cavé agreed to supply new engines for the ship under the original contract. When Isly ran trials with her second set of machinery in 5.56 her displacement was 2915t and her mean draft 20ft 6in (max 22ft 8in). Due to her machinery problems, she entered service a full decade after being laid down and lost most of her significance as France's pioneer high-powered screw frigate. She pitched excessively with her 1855 armament and her captain recommended removing eight guns. She had the proportions of a 3rd class frigate but became a 2nd class frigate under the new classification scheme of 1855.

Disposal. Isly was BU at Brest 1875.