The PT Boat proved itself to be a formidable weapon during the Second World War. However, it wasn’t until a change of doctrine and an evolution in weaponry that its full potential was realised.

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The PT Boat

The concept of fast, small boats armed with torpedoes can be traced back to the late 19th century. However, it was in the interwar period that experimentation and development of PT boats began in earnest. Various countries, including the United States, conducted trials with small torpedo-carrying boats to assess their viability in naval warfare.

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An 80 foot Elco PT Boat in New Guinea, 1943.

In the United States, two main companies, Higgins Industries and Electric Boat Company (Elco), played significant roles in the development and production of PT boats. Higgins focused on the construction of wooden-hulled boats, while Elco utilized plywood construction techniques. Their designs emphasized speed, maneuverability, and the ability to operate in shallow waters.

A variation of the Elco Thunderbolt equipped with four 20 mm guns.

The typical PT boat of World War II measured around 80 feet in length, with a shallow draft and a displacement of about 20-30 tons. They were powered by gasoline engines, usually with multiple engines to achieve high speeds of around 40-50 knots. PT boats were armed with torpedoes, machine guns, and cannons, providing them with offensive and defensive capabilities.

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Change In PT Boat Tactics

During the New Guinea campaign, the Japanese operated shallow draft barges in order to resupply their forces. The barges moved at night and in extremely shallow waters, leaving Allied vessels unable to persue them. Consequently, PT boats were deployed as an alternative solution.

A view from behind the Elco Thunderbolt.

However, it soon became apparent that torpedoes proved ineffective against the shallow-draft barges, as they effortlessly passed beneath them without causing significant damage. This realization led to a strategic shift, prioritizing increased firepower to quickly engage and eliminate the enemy vessels, followed by a swift retreat to safety.

The Elco Thunderbolt

The PT boat’s increased firepower came in the form of the ‘Elco Thunderbolt’. It was a single-person electric powered turret that went through several iterations.

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An early iteration of this turret incorporated a combination of two Oerlikon 20mm cannons and six M2 .50 caliber heavy machine guns. Additional configurations were also tested, such as four Oerlikon cannons with two M2s, or solely the four Oerlikon cannons.

An early Elco Thunderbolt with six M2 machine guns and two 20 mm guns.

Regardless of the specific armament arrangement, these turrets boasted a remarkable capability where a single operator could unleash a formidable barrage of bullets towards approaching enemy targets.

The Thunderbolt was quickly employed on PT boats. However this was towards the end of the war so they saw little use.

The Elco Thunderbolt’s legacy continues to influence naval weapon design and contribute to the development of effective and efficient armament systems. In present-day naval operations, the United States Navy employs similar mounts, reminiscent of the Thunderbolt turret, for the Mk 38 Bushmaster, which is a formidable 25mm chain gun.