Thanks for these informations, and excuse me for my poor english.
1) Speed over 7"
The -1 penalty for targetting fast ships is the same than the -1 penalty for targetting at long range. Nobody complains about not hitting Battleships or Cruisers when at long or extreme range. Try this : if you need a 7 to hit on a 6 sided die, roll it, and if you get a 6, re roll and you need a 4+ to make a 7. If you need a 8, re roll any 6 and get a 5+ to make an 8 and for a 9 you need a 6 and another 6. You can prefer to say 5+ for a 7, 6 for an 8 and impossible for a 9 needed. For example.
It's the way that I play and it seems quite balanced (with Royal Navy, Kriegsmarine and Italian navy).
The -1 penalty applies only if the current speed of the target is MORE than 7". Only a few Japanese destroyers get this speed (about 8 ships of the Fubuki class, and only 1 ship of the Shimakaze class). For the other, their speed is "only" 7 and they need to make a "Flank Speed" to reach 8". You can easily create a rule that says "a ship may only make a "flank speed " for 1 turn, if it does a second turn, roll a die, on a 6 the engines are damaged (for example : speed -2" or speed -1", as a critical hit). For information US Navy also gets destroyers with a 8" speed (Gridley class).
Don't forget you have a +1 bonus when firing on large silhouette.
You can also try to hit with a dive bomber from a carrier wich get a+1 bonus when bombing their target, or use Ship launched torpedoes (difficult because of the 10" range) wich ignore normal penalties or bonus and just apply a +1 bonus if targeted on the beam.
If you use the special rule for radar, firing in daylight and by clear weather with a radar ignore the long range penalty for turrets and reduce penalty by 1 at extreme range for turrets. You can easily spend 1 shot with such a turret to try to get definetly rid of these destroyers.
And finally, some US ships get a 14" range for secondary weapons as Wyoming, Colorado, New Mexico, New York, Sangamon, Long Island classes.
As you see, I think there are many ways to try to hit these small ships
Example: US Tennessee class using a radar (daylight, clear weather) at 25", firing at a Japanese destroyer at a speed of 8" on its beam.
Target 6, -1 penalty for speed, no penalty for long range, +1 bonus for firing on large silhouette , total to roll : 6. You have 4 turrets with 3AD each , you roll 12 dice (what the probability not to roll any 6 ?) damage is 2 DD AP with an armor of 2+ for the destroyer. I'm just laughing.....
2) Powerfull Japanese torpedoes
Don't forget that, if the Japanese choose long range torpedoes (they can opt to fire their torpedoes normally, at 10"), they roll the dice to hit on the next turn they announce they're firing. So US Navy ships have a turn to try an evasive manoeuvre.
