I originally did these as part of the Fisherless RN, but they are actually armed as per their real life counterparts.
Vosper 73 ft motor torpedo boat
(From Wikipedia)
The Vosper 73 foot motor torpedo boat was a mid-twentieth century British military boat design by Vospers.
At 73 ft (22 m) long they were considered small boats compared to longer designs such as the Fairmile Type D. The design came about from a requirement that British Motor Torpedo Boats should be better able to fight small craft, which was the job of Motor Gun Boats. To this end Vospers built on their existing 70 foot designs. The Type I was introduced in 1943 and the Type II before the end of the Second World War.
The boats carried four 18-inch torpedo tubes as their major offensive armament along with Oerlikon 20 mm cannon and some defensive armament (Vickers K machine guns) for protection against enemy aircraft. The Type II gave up two torpedo tubes, but gained a 6-pounder gun which displaced the twin Oerlikon to the aft deck. This made it more capable of performing the Motor Gun Boat role.
Built: 1943-1945 Planned: 32 Completed: 29 (17 × Type I, 12 × Type II) Cancelled: 3 (Type II) Lost: 1 (MTB-530, lost in a collision off Hook of Holland, Netherlands on the 28th March 1952.)
General characteristics
Type: Motor Torpedo Boat
Displacement:
Type I
44.5 long tons (45 t)
Type II
48.75 long tons (50 t)
Length: 73 ft (22 m)
Beam: 19 ft 6 in (5.94 m)
Draught: 3 ft (0.91 m)
Propulsion: 3 × 1,400 hp (1,044 kW) Packard petrol engines
Speed: 40 knots (74 km/h; 46 mph)
Complement: 13
Armament: Type I
4 × 18 in (457 mm) torpedo tubes
1 × 20mm Oerlikon gun
2 × .303 Vickers K machine guns
Type II
1 × QF 6 pounder gun
2 × 18-inch torpedo tubes
1 × 20mm Oerlikon gun
2 × .303 Vickers K machine guns
Armour: Armour plate around the bridge