Lets look at RN studies for armoured-deck carriers.
Design J is closest to 17500tons
J (with armoured flight deck)
600ft 84ft 22
17,000 tons std
20.000 deep
66,000 shp
3 shafts 28kts
Endurance 10000 nm at 12kts
2*twin 5.25in
4*8 barrel pom poms
24 TSR (hanger capacity)
660 by 84 flight deck
436*60*16 hanger
Lifts 45*22
40000 gallons of petrol
180*500lb bombs
150*250lb bombs
£3 million
Designs f and J had 2.5in NC steel flight deck covering full width of Flight deck and 400/480ft respectively in length (covering full hangers in both and then extending aft beyond). Both had 2in forward bulkhead. For an extra 600 tons design J could have a 3in flightdeck. All NC.
For F and J Belt 4.5in C armour covering Mags and machinery which ran from HD to 3.5 ft below waterline. Reducing this belt to 3in would save 220 tons and £45000.
Shes slower, less heavily armed and carries far fewer aircraft. Probably around 40 ac with a deckpark. Serious limitations with fuel and ordnance stowage.
You actually need flight deck armour plus armour lower in the ship, else you have very little defense against shellfire.
JA
3 in flight deck, 2in deck armour over machinery, displaced 17,800tons for 28.75kts boilers forced. For an extra £130000
JB
3in flighdeck extended just over the width of hanger only, with 4.5in CA carried all the way up to the hanger deck from mags to machinery and back to mags. Hangers covered by 3in NC with hanger deck covered in 1.75in NC over mags and machinery. Displaced 17,560 tons for an extra £110,000.
JC
3in flight deck covers full width of flight deck, 3in NC hanger deck over vitals and 1in hanger sides. Displaced 17,890 tons and had 2ft extra beam in compensation (+£170,000).
JD
As JC with 4.5in belt extended over entire hanger sides. The protected area of flighdeck was reduced from 480ft (JA JC) to 436ft. Displacement 18,370 tons, 80.000shp for 27.75 kts. (+£250.000)
Design M
LBP (ft) 600
LWL (ft) 625
LOA (ft) 650
BEXT (ft) 88
17,440 tons std
22.9ft draught 26.9 deep
Flight deck freeboard 41.8ft
Shp 102,000 shafts 3 for 29.75 kts
Feul 4000tons for 12,000nm at 14kts
1000 complement
25.000gallons of petrol
8 * 4.5 in guns arranged in twin BD mounts superfiring fore and aft of island
2 * 8 barral pompoms
Aircraft 18 hanger plus 6 deck park
Protection
4.5in side C
2.5in Bulkhead NC
1in D hanger bulkhead
Deck 3in
Flight deck 3in
Design N
LBP (ft) 650
LWL (ft) 675
LOA (ft) 700
BEXT (ft) 83
16,500 tons std
19.6ft draught 23.6 deep
Flight deck freeboard 43.9ft
Shp 100,000 shafts 4 for 30.5 kts
Feul 3500tons for 10,000nm at 14kts
1000 complement
28.000gallons of petrol
8 * 4.5 in guns arranged in twin BD mounts superfiring fore and aft of island
4 * 8 barral pompoms
Aircraft 20 hanger plus 6 deck park (note old type)
Protection
3.5in side C
1.5in Bulkhead NC
1in D hanger bulkhead
Deck 2in
Flight deck 2.5in
Stearing 2.5in
Underwater 750lb
The major problem I think is that to actually sim the deck armour as the flight deck you must have the freeboard at that level for the entire length of the armoured flight deck, so that the stability can be taken into account.
Not quite. Use your engineering skills and do a few moment calculations