Old/PT Imp Group

Info

PT Imp Group Abyssal Class Patrol Torpedo Boat

Statistic
HP	9	Firepower	9
Armor	29	Torpedo	98
Evasion	'	AA	18
Aircraft	'	ASW	'
Speed	'	LOS	'
Range	'	Luck	'
Equipment			Space
22inch Torpedo Mk.II			-
22inch Torpedo Mk.II			-
-			-
-			-

PT Imp Group Abyssal Class Patrol Torpedo Boat

Statistic
HP	15	Firepower	15
Armor	29	Torpedo	98
Evasion	'	AA	18
Aircraft	'	ASW	'
Speed	'	LOS	'
Range	'	Luck	'
Equipment			Space
22inch Torpedo Mk.II			-
22inch Torpedo Mk.II			-
-			-
-			-

PT Imp Group Abyssal Class Patrol Torpedo Boat

Statistic
HP	18	Firepower	18
Armor	39	Torpedo	118
Evasion	'	AA	24
Aircraft	'	ASW	'
Speed	'	LOS	'
Range	'	Luck	'
Equipment			Space
22inch Torpedo Mk.II			-
22inch Torpedo Mk.II			-
-			-
-			-

Unlike most standard Abyssal enemies, the PT Imp Group are relatively small and fast. Attacking them with large-caliber guns will not do much damage; smaller guns are recommended to deal normal damage.
On 11/20/2015 a tweet revealed that there was a bug that prevented destroyers from being able to hit the PT Imp Groups. As a result the devs have readjusted the damage the damage calculations in a live patch update on the same day.
As it stands currently PT Imp Groups are vulnerable to attacks that come Destroyers, light cruisers, and ships equipped with Secondary caliber gunnery such as the 15.2cm Naval Gun, 15.5cm Triple Gun Mount (Secondary), 10cm Twin High-angle Carriage Mount and so forth. Please refer to the List of Secondary Guns for more details.