Aso (PL 41)
Class overview
Name	Aso class
Builders	Mitsubishi Heavy Industries, Universal Shipbuilding Corporation
Operators	Japan Coast Guard
Preceded by	Ojika class
Succeeded by	Hateruma class
Subclasses	TT-1500 design
Built	2002–2006
In commission	2005–present
Planned	3
Completed	3
Active	3
Class overview
Name	TT-1500 design
Builders	TBA
Operators	Vietnam Coast Guard
Preceded by	Han River-class vessel
Cost	USD $398,430,000 for six vessels
Built	Jul. 2020 - Oct. 2026 (planned)
Planned	6
On order	6
Completed	0
Active	0
General characteristics (Aso class)
Type	1,000 ton-class PL (Patrol vessel, Large)
Tonnage	770 GT
Length	79.0 m (259 ft 2 in)
Beam	10.0 m (32 ft 10 in)
Depth	6 m (19 ft 8 in)
Propulsion	4 × Waterjets 4 × diesel engines
Speed	30+ knots
Complement	30
Armament	One Bofors 40 mm L/70 gun with optical FCS
Armour	Ballistic protection over certain areas
Aviation facilities	One helipad (TT-1500)
General characteristics (TT-1500)
Type	General-purpose TT (tuần tra)-classification offshore patrol vessels
Displacement	1,500 ton
Length	79.0 m (259 ft 2 in)
Beam	11.0 m (36 ft 1 in)
Height	6.8 m (22 ft 4 in) (freeboard)
Draught	3.3 m (10 ft 10 in)
Speed	24 knots (44 km/h; 28 mph)
Range	4,000 nautical miles (4,600 mi; 7,400 km)
Armament	Primary weapon station(s) using the ZU-23-2 or PT-306 autocannons with optoelectronics-based FCS Secondary weapon stations using the 12.7mm NSV or the 14.5mm KPV heavy machine guns, likely remote-controlled
Aviation facilities	One helipad
Notes	Characteristics extracted from the 2018 initial projection and likely become subjects to be changed

The Aso-class patrol vessel is a class of PL type patrol vessel of the Japan Coast Guard. PL stands for Patrol vessel Large, and the class is named after Mount Aso, the largest active volcano in Japan.

This class is one of the new patrol vessel classes to intercept spy boats of DPRK. These classes are called "高速高機能大型巡視船", High-speed, high-functionality patrol vessel, large. Having Bofors 40 mm L/70 autocannon with fire-control system, this class is safely able to deal with heavily armed spy boats of DPRK which intrude into Japanese waters. The hull of this class is bulletproof in case of close-range firefights.

In the back of the bridge's side, this class has display devices that can be used to instruct other ships to stop even at nighttime. And on the bridge superstructure, this class is equipped with the LIDAR system to acquire targets with high accuracy. At the same time, this system enables them to perform search and rescue missions more safely.

Vietnamese variant

In 2020 there was signed an export deal between Japan and Vietnam over 6 vessel for the Vietnam Coast Guard (VCG), locally designated as the "TT-1500 patrol ship".^[1][2]"TT" stands for "Tuần tra" means "Patrol", meanwhile the number "1500" stands for the class's displacement of 1500 tons. According to pieces of information shared by VCG, TT-1500 has a slightly bigger size than the original Aso-class, and it is also equipped with a helipad and the overall design is likely inspired from the successor designs such as the Kunigami-class patrol vessel.

The TT-1500 will have a maximum speed of 24 knots, considerably slower than the original Aso, however it is projected to have a better low-speed stability hence making it better for low-intensity patrol and search-and-rescue missions.^[3] The delivery for all 6 ships is expected to be completed by October 2026.^[4]

Ships in the class

Ships in the class

Pennant number	Ship name	Builder	Commission	Homeport
Japan Coast Guard (Aso-class)
PL 41	Aso	Mitsubishi Heavy Industries	15 March 2005	Fukuoka
PL 42	Dewa	Universal Shipbuilding Corporation	12 April 2006	Akita
PL 43	Hakusan			Kanazawa
Vietnam Coast Guard (TT-1500)
CSB 8***		TBA