Various claims have been made as to the speed of Cerberus. The evidence below shows that Cerberus regulary exceeded 10 knots and on at least one occasion achieved a speed of 12.4 knots.
1869 - 9.75 knots
"9.75 knots at full power at 100.35 RPM on the Starboard Shaft and 100.59 on the Port Shaft.
8.403 knots at half power at 86.54 RPM on the Starboard Shaft and 87.33 on the Port Shaft."
1870 - 10.00 knots
"The Cerberus was originally designed for a speed of 8½ knots an hour, but on her trial trip she went 10 knots, 1½ beyond her contract speed."
1871 - 9½ knots
...but this was beaten coming up the Bay yesterday, when a speed of 9½ knots was attained with a full head of steam. ("coming up the Bay yesterday" refers to the arrival of Cerberus from Britain with an extra mast, temporary iron deck and raised bulwarks.)
1871 - 9 knots at 86 rpm
The twin screws and the four engines were in operation, and the highest speed attained was 9 knots, with 86 revolutions of the screw.
1871 - 10 knots
...with apparent ease, and despite bad coal and a foul bottom, she made 10 knots an hour...
1874 - 11 knots
"The average speed attained on Saturday during the trip was 11 knots and that without undue firing up or extraordinary pressure."
1875 - 10¾ knots
"...at what rate can the Cerberus steam?"
"If she could come up full speed - 10 knots - she has done as much as 10¾....
1876 - upwards of 10 knots
she made excellent speed, her steaming being upwards of 10 knots per hour. (straight out of the A.G. Dock) The Argus, 21 June 1876
1883 - 9 knots
"Under 28lb. of steam, the engines make 86 revolutions per minute, the speed was logged at fully 9 knots an hour. That was the best result attained, and under the circumstances it may be considered most satisfactory. It must be understood however, that the boilers and pipes are not yet covered with non-conducting material, and a large amount of power is lost by radiation."
1887 - 10 knots
"The Cerberus had the Gordon (torpedo boat) in tow, but she was nevertheless able to steam 10 knots an hour, and get well ahead of the Albert."
1890 - 7 knots at 74 rpm
On 12 July 1890, 7 months since last going into Dry Dock to have the hull cleaned, the Cerberus Log book recorded a speed of 7.0 knots at 74 revolutions. (included to show how engine speed related to ship speed)
1900 - 12.4 knots
"With a clear sky and the Bay as calm as a mill pond, everything portended a successful cruise in the Cerberus.
.....Commander Tickell had a speed trial over a measured mile laid by the patent log, which showed the time record to be 12.4 knots per hour."
"When off Werribee the Cerberus ran a speed trial over a measured mile, at a rate of 12.4 knots an hour. The speed recorded on the trial run of the Cerberus when she was built was 9½ knots. To-day's run is accounted for by the overhaul recently given to the engines."
Cerberus had been dry docked to have her hull cleaned one month prior to this occasion. (10-20 March 1900)
(12.4 knots = 22.94 kph)
On April 13 the Cerberus log recorded :-
ship steamed measured mile in 4 m 42 s
2.35 (pm) ship steamed measured mile in 4 m 40 s
9 knots at 86 rpm (16 September 1871)
Under 28lb. of steam, the engines make 86 rpm, the speed was logged at fully 9 knots an hour (17 Oct 1883)
7.0 knots at 74 revolutions (12 July 1890)
Her propellers are made to make 100 revolutions in a minute, which is equal to a speed of 9¾ knots an hour. North Otago Times, 12 May 1871