BTW one for Nick SCC in the context I stated here stands for Ship Control Centre !

But the answer I was looking for is as follows :-

When the cracks were first detected the action was taken immediately in order to mitigate the problem from getting worse before the next refit was due

(Personally I wonder if this was the reason the whole class was sold off in the early 90's - it may have cost a huge amount of money to cure the problem completely - also the FI Conflict proved that aluminium and steel was not a good combination on ships).

Restrictions put in place only to be ignored in time of war

1. Ollies to be run at no more than 80% of capacity (Set lever 8 - 0)
2. Maximum amount of rudder to be used is 20%

As I said probably only drilled into you as a watch keeping officer or on duty in the SCC.

On a personal note I think the T21 was one of the best looking warship the UK ever had with the original Daring Class coming a close second YMMV

All I can think of are restrictions to speed and/or sea state. Possibly limiting weight of weapons systems...

Give you a clue you would probably only know the answer to this if you worked on the bridge of a T21 or in the SCC

You are all quite aright about the hulls being reinforced but the question clearly stated "What peace time restrictions were put on the operations" this happened before the steel reinforcement but to my knowledge remained in place long after

Hey Pat I think you picked Doug's favorite topic.
He is very prepared.

A mate of mine was in the Comms branch on HMS Arrow. Engines 2 x Tyne, 2 x Olympus. Hulls were reinforced with steel plates...

2 x Rolls Royce Tyne RB.109 Cruise turbines 8500shp. 18knots.
2 x Rolls Royce Olympus Boost turbine 50,000shp. 32 knots standard, 37knots boost.

Restricted to 'Shallow' water operations after the ships developed cracks in their decks during South Atlantic Falklands operation, due to the different strength and fatigue properties of steel and aluminium. Steel reinforcing plates were added.

Ardent and Antelope were the ships lost to Argentine bombs 21st and 23rd May 1982 respectively. Partly due to the poor fire resistance of aluminium.
No more RN ships were built with aluminium superstructures, which were only used on the Type 21 to try to compensate for the much lighter turbine machinery which made top weight critical. Many harsh design lessons were learned🤔
😎

The Type 21 Frigate a total of 8 ships were built (two of which were sunk in combat) where used by the Royal Navy and later the Pakistan Navy was an all Gas Turbine propelled ship.

Again a two part question.

1. What Gas Turbines were used to Propel the Type 21 Class of Frigate
2. What peace time restrictions were put on the operation of the Type21 when cracks appeared the the aluminium superstructure.

Good luck Shipmates