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GTÉ TACT
The TACT (Tracked Amphibious Cargo Transporter) was designed by Grúpa Thionscal Éireann (GTÉ) to meet a perceived need in export markets for capable amphibious vehicles. It was the first tracked vehicle designed by the firm, and was designed with input from the British Army, Royal Marines, and Irish Defense Forces.

The TACT was a large vehicle with a watertight but open-topped hull. A large tailgate served as a rear ramp that allowed cargo, troops, or light vehicles to be loaded. The crew of two sat in a lightly-armoured enclosed cabin at the front; a hatch in the ceiling allowed the assistant driver to operate a ring-mounted Breire machine gun. Two V-6 engines were located side-by-side in the front, under the floor of the vehicle. Each engine drove one track and one propeller on the rear hull. The propellers could be disengaged from the drive and raised into a protective casing during road operations, in order to protect them from damage on road obstacles. In order to save money and design time, GTÉ used a number of suspension components (such as roadwheels and tracks) from the British Centurion tank, as well as off-the-shelf transmission components. Although the TACT was large (longer and taller than a Centurion tank) it was mostly unarmoured and weighed approximately eighteen tons empty.

The TACT's cargo bed was large enough to securely stow a standard lorry of 2.5 - 5.0 tons for amphibious transport, or a cargo of up to ten tons or an infantry platoon for road transport. Additionally, the TACT had a trailer mounting to tow the T5T five-ton amphibious trailer. The two-axle T5T was capable of carrying another five tons of cargo on water or on land. Outrigger-like pontoons could be folded down and attached to the hull in order to enhance the water stability of the cargo trailer. Like the TACT, the T5T had a rear ramp that could be lowered in order to easily load cargo or small vehicles. In operational use, the combination of the TACT and the T5T trailer would allow the transport of an artillery piece and its caisson in a single load.

Manufacture of ten prototype and pre-production vehicles began in the fall of 1946, with seven (and five T5T trailers) completed by January of 1947, when production stalled due to severe winter conditions. When the heavy snows melted and caused flooding in Ireland and Great Britain, four of the prototypes were used in the Republic to move relief supplies, while three vehicles and three trailers were sent to England to assist in relief operations there.

Specifications
Crew: 2 (driver, assistant driver/gunner)
Dimensions:
-- Length: 12m (o/a)
-- Width: 3.2m
-- Height: 3.3m
Weight: 18 metric tons (empty)
Armament:
-- 0.303cal Breire MG, ring mount with 300 rds
Payload: 5 metric tons (water); 10 metric tons (land)
Protection:
-- Cabin: 8mm-15mm
Engine: 2x GTÉ 575 V-6 diesel engines (5750 cc, 165hp), 330 hp total
Transmission: Manual, 5 speeds forward and reverse
Suspension: Horstmann suspension; six road wheels
Power Weight Ratio: 18.3 hp / tonne
Speed: 40kph (road), 10kph (water)
Fuel Capacity: 165 gal (625L) internal fuel
Range: 380 kms
Manufacturers: Grúpa Thionscal Éireann (GTÉ)

Advantages:
- High payload for an amphibious vehicle, particularly with optional trailer
- Tracks and high power-to-weight ratio allows vehicle to more easily climb out of water on steeper slopes
- Low ground pressure allows for better movement on soft and boggy ground
- Rear ramp allows easy loading and unloading of cargo
- Main cargo bay large enough to accommodate small lorry

Disadvantages:
- Damage to or malfunction of one engine results in potential immobilization.
- Due to one engine operating one track, steering can be awkward during acceleration or at very low speeds
- Rear cargo ramp cannot be lowered when trailer is attached
- Complete lack of armour everywhere but around operator cabin
- Somewhat more expensive than a wheeled amphibious vehicle

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