What is the Swift Sea Stalker (S3)?

The Swift Sea Stalker (S3) is a 6 meter (19.2 ft) unmanned surface vehicle built by Swiftships. It has a 5086 marine-grade aluminum hull, diesel propulsion, multi-spectral sensors, Starlink beyond-line-of-sight communications and a modular mission payload bay, and it can be operated remotely, under supervision or autonomously.

How fast is the S3 and how far can it go?

The S3 reaches 45+ knots with a Yanmar 4LV230 diesel and outdrive. It carries 400 gallons of fuel for a range of over 1,000 nautical miles and an endurance of 30+ hours, and it can be refueled at sea.

What payloads can the S3 carry?

The modular payload bay takes up to 1,250 lb. Options listed by Swiftships include multi-spectral ISR sensors, JAGM and JAGM-MR missiles, Switchblade 300 and 600 loitering munitions, the TSC Growler electronic-warfare package, a Dillon Mini Auto Gun and high-explosive energetics for one-way attack.

How is the S3 transported and deployed?

The S3 and its trailer fit inside a standard 20 ft (TEU) container and can move by air, sea or land. It ships as a kit or fully assembled, and 32 S3s can be carried and deployed by the 62 m S5 Support Ship.

Which standards does the S3 comply with?

The S3 uses an open system architecture with plug-and-play command and control and complies with NATO STANAG 4586 and the Joint Architecture for Unmanned Systems (JAUS), so it integrates with existing command-and-control systems.

Has the S3 been selected by the US Department of Defense?

Yes. In March 2024 Swiftships announced that the US Department of Defense (OUSD and the Naval Surface Warfare Center) selected the Swift Sea Stalker S3 as a small unmanned surface vehicle supporting the Replicator programme. The craft is at Technology Readiness Level 9.

How many S3s can Swiftships build, and where?

Swiftships states a robotic-welding production rate of 15 to 20 craft per month. The S3 is built at the company's Louisiana yards; its autonomous programmes are based in Jeanerette, with headquarters in Chantilly, Virginia.

Swift Sea Stalker (S3) – 6 m Unmanned Surface Vehicle, 45+ kn

Name: 6M Swift Sea Stalker (S3)
Brand: Swiftships

S3 · Unmanned Surface Vehicle

A 6 meter unmanned surface vehicle built for high endurance, survivability and mission flexibility. Cyber hardened, ready at scale.

Unmanned Surface Vehicle
Dominating Asymmetric Warfare
Cyber Hardened

The vessel, in brief

The Swift-Sea-Stalker (S3) is designed for high endurance, survivability, and mission flexibility, featuring a durable aluminum frame with a self-scuttling hull. Powered by diesel and equipped with multi-spectral sensors, BLOS communications, and a modular mission payload bay, this autonomous USV enables cooperative operations and multi-day navigation with a range of 1,200 NM and a payload capacity of 1,250 lbs. The S3 and its trailer can fit into a 20’ TEU container and are available as a kit or fully assembled, offering flexibility for rapid deployment.

Top speed: 45+ KN
Range: 1,000+ NM
Payload: 1,250 LBS
Endurance: 30+ HRS

01 // Capabilities

Game changer. Game enabler.

01 / 06

Fast

45+ knots

A Yanmar 4LV230 diesel and outdrive push the S3 past 45 knots.

⟲ Drag to rotate · + for systems

03 // Specifications

Full specifications

The S3’s modular open system architecture, plug-and-play command and control (C2), and advanced ISR capabilities are designed to support expeditionary maritime operations, aligning with Joint Warfighting Concepts (JWC). The S3 complies with NATO Standardization Agreements (STANAG) 4586 and the Joint Architecture for Unmanned Systems (JAUS) protocol.

Download spec sheet

Dimensions

Length: 19.2 ft (6 m)
Beam: 6 ft (1.82 m)
Draft: 6.6 ft (1.98 m)
Freeboard: 1.33 ft
Weight: 3,160 lbs

Performance

Speed: 45+ knots
Range: 1,000 NM+
Range w/ refuel: 1,000 NM @ 35 kn cruise
Endurance: 30+ hours
Fuel capacity: 400 gal
Fuel: Diesel Type #2 or JPL
Power: 16,200 kWh

Machinery

Engines: Yanmar 4LV230 [3,800 RPM]
Propulsion: Yanmar Outdrive
Generator: 3 kW (optional)

Sensors / Electronics

Radar: SIMRAD HALO 24
NAV: Vector Navigation VN-300
AIS: Sitex DA-2
GPS: TE Connectivity ANT-SH2-SMA
Comms: Starlink BLOS
Camera: FLIR M364C low-light, HD night vision
Antenna: L-COM HG2406DPU · Shakespeare 5912

Payload Options

Payload: Modular, up to 1,250 lbs
Missile: JAGM / JAGM-MR
Loitering munition: Switchblade 300 / 600
EW: TSC GROWLER
Gun: Dillon Mini Auto Gun
Energetics: High explosive for One Way Attack (OWA)

Other

Hull: 5086 Marine Grade Aluminum
Sea state: Operate / Survive (2–3)
Production: Robotic, 15–20 craft / month
Transportable: Air, Sea, or Land
TRL: 9 (Craft), 7 (Technology)
Watertight: Unsinkable

04 // Teaming & support

Militarized unmanned and minimally manned vessels

Teaming32S3s deployed by one S5 Support Ship
The S5, a Large Unmanned Surface Vessel on a proven Fast Supply Vessel hull, carries and deploys the S3 at scale.
Meet the S3-HP
Autonomy, proven4,421Nautical miles, 98% in autonomous mode
Nomad (formerly Riley Claire) sailed from the Gulf Coast through the canal to the US West Coast, one of two offshore vessels Swiftships converted to autonomous operation.
Co-productionYour yardOr ours
We can build your vessels at our location, or support full construction at yours: Swiftships has extensive experience with international co-production programs.
Contact us

05 // The fleet

Other vessels

24 hulls

05 // Questions

Sea Stalker, answered

What is the Swift Sea Stalker (S3)?: The Swift Sea Stalker (S3) is a 6 meter (19.2 ft) unmanned surface vehicle built by Swiftships. It has a 5086 marine-grade aluminum hull, diesel propulsion, multi-spectral sensors, Starlink beyond-line-of-sight communications and a modular mission payload bay, and it can be operated remotely, under supervision or autonomously.
How fast is the S3 and how far can it go?: The S3 reaches 45+ knots with a Yanmar 4LV230 diesel and outdrive. It carries 400 gallons of fuel for a range of over 1,000 nautical miles and an endurance of 30+ hours, and it can be refueled at sea.
What payloads can the S3 carry?: The modular payload bay takes up to 1,250 lb. Options listed by Swiftships include multi-spectral ISR sensors, JAGM and JAGM-MR missiles, Switchblade 300 and 600 loitering munitions, the TSC Growler electronic-warfare package, a Dillon Mini Auto Gun and high-explosive energetics for one-way attack.
How is the S3 transported and deployed?: The S3 and its trailer fit inside a standard 20 ft (TEU) container and can move by air, sea or land. It ships as a kit or fully assembled, and 32 S3s can be carried and deployed by the 62 m S5 Support Ship.
Which standards does the S3 comply with?: The S3 uses an open system architecture with plug-and-play command and control and complies with NATO STANAG 4586 and the Joint Architecture for Unmanned Systems (JAUS), so it integrates with existing command-and-control systems.
Has the S3 been selected by the US Department of Defense?: Yes. In March 2024 Swiftships announced that the US Department of Defense (OUSD and the Naval Surface Warfare Center) selected the Swift Sea Stalker S3 as a small unmanned surface vehicle supporting the Replicator programme. The craft is at Technology Readiness Level 9.
How many S3s can Swiftships build, and where?: Swiftships states a robotic-welding production rate of 15 to 20 craft per month. The S3 is built at the company's Louisiana yards; its autonomous programmes are based in Jeanerette, with headquarters in Chantilly, Virginia.