So, the original USS Hornet, CV-8 of the Yorktown class, is the basis?
A sub has 1, maybe 2, 5in/25 caliber cannons. (125in barrel, muzzle velocity of some 2,100fps, range of 14k yards max)
http://www.navweaps.com/Weapons/WNUS_5-25_mk10.htm
The Yorktown class used 5in/38 caliber cannons (190in barrel, muzzle velocity of around 2,500-2,600 fps, range of 17k yards max), on top of 450 rounds per gun.
http://www.navweaps.com/Weapons/WNUS_5-38_mk12.htm
Toss in the 20mm and 28mm guns, and it can easily take out stuff compared to the deck and AA guns of a sub.
With 8x5in/38 caliber guns (4 each side), that would be an average of 1x 5in shell fired, per side, per second.
Don't really need torpedoes.
Just drive into the middle of a convoy and pray the escorts don't have torpedoes.
(or find a way to make a playable carrier with the ability to deploy aircraft, or just shell them at max range and pray the escorts don't have long lance torpedoes)
Personally, I would go with a pre WWII Lexington class if it came to use a carrier that could not use aircraft. The pre-WWII Lexington class carriers were armed like cruisers, with 4x dual 8in cannons.
(although they were removed because firing them would apparently have torn the wooden deck apart... not that they cared much about aircraft when it was originally built post WWI)
Random thoughts for whoever might work on this idea.
Being a carrier is roughly 4 times wider than a fleet sub, it seems like it would be a easy task to have more than just 2 fore tubes below the waterline.
Maybe 8 fore and 2 aft? Or 6 fore and 4 aft like the big fleet subs if 8/2 is not possible?
Maybe having a quicker reload speed due to having plenty of space and power for extra machinery/equipment and/or manpower?
The large torpedo load sounds alright.
Rather than torpedoes, would it be possible to create 'invisible' tubes on the carrier deck that would 'launch' fighters?
Would it be possible to take a bit from the Lexington design and maybe find a way to mount smaller dual barrel 5in (or 6in?) turrets for and aft of the island for some added punch if aircraft are not a viable option for a playable carrier?
Looking online for info about the USS Hornet.
There are two different USS Hornets in WWII
CV-8, Yorktown class, launched Doolittle raids, sunk in 1942.
http://en.wikipedia.org/wiki/USS_Hornet_%28CV-8%29
Info on her assorted weapon loads.
She has been packing a fair bit more AA guns by the time she was sunk in 1942.
8 × 5 in/38 cal dual purpose guns
20 × 1.1 in/75 cal (a.k.a. 28mm)
32 × 20 mm
CV-8 more closely matches the info you posted.
CV-12. Essex class, originally USS Kearsarge, until renamed after the sinking of the CV-8 USS Hornet.
http://en.wikipedia.org/wiki/USS_Hornet_%28CV-12%29
Very well armed when built, so likely not the one you meant.
4 × twin 5 inch (127 mm) 38 caliber guns
4 × single 5 inch (127 mm) 38 caliber guns
8 × quadruple 40 mm 56 caliber guns
46 × single 20 mm 78 caliber guns
Overall, with SH5 seeming to be a dud, and with starting to miss SH4, this subject seems to be very interesting.
(unfortunately, my modding skills are limited at best, limited to whatever simple edits can be via notepad, so I can't do much beyond toss out random ideas and comments)