I’m going to copy across what I posted on reddit, as my sort of feedback in regards to submarines as they are in the current event and what I think could be added/removed prior to them being put into naval proper:
So we’ve got the uboat vs destroyers event now which is quite possibly a test run for the introduction of submarines into naval. I think this has the opportunity to be a lot of fun, but there are a number of tweaks that I think might be needed before they are added.
Uboats
Longer dive times, option for Crash dive similar to the Blow Ballast option (r)
Harder for AI spotters to spot at distance/weather conditions/night
Can hear enemy destroyers/freighters when dived, the slower the speed the longer the range. Options for researchable sonar upgrades (GHG to KDB to Balkon, etc)
Dive deeper than 60m
Give deck gun back
Longer range torpedoes than 2000m.
No deck gun or AAA gun when mostly underwater.
Rear torpedo tube for torpedoes, mines optional loadout.
Destroyers
Passive Sonar has a longer range the slower the ship travels, at flank speed it could run over a stereo and not hear it
ASDIC fairly well implemented in game, be sure that there’s the blind spot underneath though.
Depth charges need to be manually set between shallow, medium and deep
Hedgehogs where historical
Radar where historical?
General
In RB Naval, seperate spawn points for submarines that aren’t visible from the enemys spawn like current surface spawns are.
Submarines will probably be more useful in Enduring confrontation like bombers are
If the goal is to attack a convoy, then submarines should have the chance to get ahead of the convoy and dive. Will stop the destroyers spawn camping the submarines?
Special submarines, Surcouf, I-400 (launches planes like Battleships do in game now), maybe HMS X1? Gyro-copter for later uboats?
The bigger the submarine the longer the dive time.
Dive times, torpedo reloads and such can be affected by crew skills
Radar for submarines where historical, radar detection for subs where historical
Radar for anti submarine aircraft?
Night battles? Spotlights, star shells? Big disadvantage for ships without radar though (Cape Matapan).
Different torpedoes for different navies, but limited by BR, so a Type VIIA at a lower battle rating than a VIIC/42 wouldn’t be able to carry G7es homing torpedoes.
Foxer noise makers for Destroyers at the right BR, BOLD for uboats