Underwater defence technology company Drass recently handed over two new submersible swimmer delivery vehicles (SDVs) to the Indonesian Ministry of Defence for use by the Indonesian Navy.
The 7.7- by 1.6-metre (25- by 5.2-foot), four-ton SDVs are equipped with advanced autonomous capabilities, integrating state-of-the-art guidance and navigation systems alongside a fully featured optronic periscope suite.
Drass said that all autonomous functions of the SDVs were rigorously validated during comprehensive at-sea trials, confirming the platforms' reliability, safety, and operational readiness.
The craft can each carry eight divers from a mothership or a submarine to a fixed or floating target and transport them back upon completion of their mission. The design ensures low observability, making the vessels for missions such as sabotage and intelligence gathering.
The SDVs each feature pilot and co-pilot control modules, a GPS, and multiple displays to enhance divers’ situational awareness even when in a low-visibility underwater environment.
A payload bay with a capacity of 250 litres of various equipment is also incorporated in each submersible.
The hull of each SDV consists of a resistant structure in FRP covered with hydrodynamic FRP fairings. Drass said the hull has been shaped to gain the best efficiency and achieve the required longitudinal and transversal strength in accordance with regulations.
The main pressure-resistant parts are aluminium or stainless-steel containers and all of them are watertight and pressure-resistant up to a depth of 100 metres (330 feet) in transit condition.
The compressed air system on each SDV can store 528 litres of air at 300 bar and supplies both the breathing and ballast tank blowing sub-systems.
A trim and buoyancy system is installed. The purpose is to maintain the best craft status and to provide a suitable solution for positive and negative buoyancy and longitudinal trim.
Power is provided by 60kWh lithium batteries divided into two redundant sections in accordance with the applied design philosophy in terms of redundancy. This arrangement can deliver a maximum submerged speed of over 6.5 knots, a cruising speed of 4.5 knots, and a range of 60 nautical miles to allow the SDVs to operate far enough away independently with a reduced risk of the mothership's location being revealed.
A hydraulic system is provided to supply hydraulic power to the manoeuvring actuators such as the rudder, the ballast tanks’ vent valves, and the TV camera mast. Hydraulic oil is supplied by a pressure-resistant hydraulic power unit in the stern of the craft.
There are two communication systems; one is a personal wireless system for each diver while the other is an onboard wired communication system. During navigation, the fixed onboard system can minimise the risk of interception without using the batteries required by the wireless system. This means that these remain fully charged and ready for use when the operators leave the SDV.
As part of the delivery program, Drass conducted extensive at-sea pilot training to ensure Indonesian Navy operators are fully prepared to deploy and manage the vehicles effectively in real-world operational environments.
The delivery of the SDVs is part of the first phase of a broader plan to enhance the Indonesian Navy's underwater capabilities.
| Eight-person swimmer delivery vehicles | |
|---|---|
| SPECIFICATIONS | |
| Type of vessel: | Swimmer delivery vehicles |
| Owner: | Indonesian Navy |
| Designer: | Drass, Italy |
| Builder: | Drass, Italy |
| Hull construction material: | FRP |
| Length overall: | 7.7 metres (25 feet) |
| Beam: | 1.6 metres (5.2 feet) |
| Displacement: | 4.0 tons |
| Capacity: | 250 litres |
| Maximum speed: | 6.5 knots |
| Cruising speed: | 4.5 knots |
| Range: | 60 nautical miles |
| Batteries: | Lithium, 60 kWh |
| Crew: | 8 |