A coast guard agency operated patrol vessels for near‑shore law enforcement, anti‑smuggling, and fisheries monitoring. The aging diesel propulsion had several issues:
Loud and high vibration – Made low‑speed tracking easily detectable, losing tactical surprise.
High fuel consumption, limited endurance – Frequent high‑speed intercepts burned fuel quickly, reducing multi‑day patrol capability.
Strong thermal signature – Easy target for infrared detection.
Idling diesel was still needed to power radar and communication equipment, creating noise that interfered with audio surveillance.
We designed a diesel‑electric parallel hybrid system for the patrol vessel, adding:
LanghESS‑S1 modular battery system (high capacity for a full day of low‑speed silent tracking)
Shaft motor/generator (reversible for propulsion and charging)
Smart energy management system (one‑button switch between three modes)
Shore / onboard charging interface (fast recharge in port)
Three operation modes:
Silent electric mode – Low‑speed transit, tracking, or loitering. Zero emissions, extremely low noise, minimal vibration and thermal signature.
Boost hybrid mode – During high‑speed interception or heavy load, diesel and electric motor work together for quicker acceleration.
Silent idle mode – At anchor or drifting, battery powers comms, radar, and detection gear; main engine off for quiet listening.
Greatly enhanced tactical stealth – In silent mode, noise drops to ambient background, thermal signature near zero – difficult for suspicious vessels to detect.
Extended patrol endurance – Hybrid operation cuts fuel consumption by 30–40%, adding 1–2 days of patrol on the same fuel load.
Faster response – Boost mode provides extra instantaneous power for improved acceleration and short‑range sprint capability.
Reduced logistics burden – Lower fuel use and less engine runtime extend maintenance intervals.
Surveillance advantage – Silent idle mode enables long‑term target monitoring without revealing presence.
Environmental compliance – Meets tightening ECA standards, zero‑emission operation in port.
