A waterjet draws water through a hull inlet and ejects it through a steerable nozzle, beating propellers only above roughly 25 knots but winning on draught, stopping power and noise. In 2026 Kongsberg launched the 33 MW Kamewa S-4L and booked its largest ever waterjet order, while HamiltonJet, MJP and Thrustmaster electrify and expand the small-jet market.
What it is and how it works
An inboard pump draws water through an inlet in the hull and ejects it through a steerable nozzle fitted with a reversing bucket. Waterjets are typically more efficient than propellers only at service speeds above about 25 knots and offer reduced draught in shallow water, per Wärtsilä; another source puts the crossover nearer 20 knots. An older technical comparison on GlobalSecurity shows why: at 16 knots a propeller reaches roughly 65 percent propulsive coefficient against about 40 percent for a jet, and best overall jet efficiency at high speed is about 59 percent, limited by inlet flow recovery. Compensating virtues are shallow draught, stopping power (Kamewa claims a stop in 1.5 boat lengths from 30 knots) and more than 50 percent lower noise and vibration above 20 knots.
Why it matters now
The segment is bifurcating. Very large steel jets serve naval and fast-ferry programmes where Kongsberg has little competition, while sub-2 MW aluminium jets for crew-transfer vessels, patrol and pilot boats are now being electrified. HamiltonJet's Electro-Hybrid Drive (EHX) pairs electric motors with diesels, and MJP's X-HT variant targets wind-farm CTVs, per MJP. Military vessels account for 38.5 percent of 2025 revenue according to one aggregator, and the 2026 order flow confirms that navies and hydrogen-ready ferries are driving the top of the range.
Key players and products
Kongsberg's Kamewa S-4L steel jet spans sizes 100 to 180 and 10,200 to 33,000 kW, with a duplex stainless steel mixed-flow pump, a dual bucket and steering nozzle system for docking, and a 25,000-hour or five-year overhaul interval, per Kongsberg. HamiltonJet's HTX47, introduced in March 2023, claims 4 percent more high-speed efficiency and 16 percent higher peak bollard pull at up to 1,630 kW input, reports MarineLink. Marine Jet Power's X Series comes in three sizes, the 280X, 310X and 350X. Doen WaterJets of Melbourne offered its DJ400 with MAN 175D engines for the Australian Army's littoral manoeuvre vessel bid, per Defence Connect, and its DJ450B-DT direct-thrust variant was inspected by Indonesia's defence ministry in 2024. Wärtsilä still hosts a waterjet product page, but whether it still manufactures jets could not be confirmed.
Figures that matter
Unit-market estimates run USD 231 to 243 million for 2025, growing about 6.4 percent a year, while broader "waterjet system" estimates range from USD 1.5 billion to 2.68 billion; one report claims about 4,300 units installed in 2025. These aggregator numbers disagree by an order of magnitude and are indicative only. The HamiltonJet efficiency and bollard-pull figures are manufacturer claims.
| Metric | Value | Source type | Source |
|---|---|---|---|
| Kamewa S-4L power range | 10,200-33,000 kW | vendor | Kongsberg |
| S-4L overhaul interval | 25,000 h or five years | vendor | Kongsberg |
| Propulsive coefficient at 16 knots, propeller vs jet | about 65% vs 40% | trade-press | GlobalSecurity |
| Crossover speed where jets beat propellers | about 25 knots (20 in one source) | vendor | Wärtsilä; MarineLink |
| HTX47 claimed gains | 4% efficiency, 16% bollard pull | vendor | HamiltonJet via MarineLink |
| Kamewa jets for Indian Navy NGMV | 18 | trade-press | The Defense Post |
| Unit market 2025 | USD 231-243 million | aggregator | Valuates, MarketPublishers |
| Military share of 2025 revenue | 38.5% | aggregator | Verified Market Reports |
Developments 2023-2026
- February 2026: Kongsberg launched the S-4L series with Gotlandsbolaget's hydrogen-ready Horizon X high-speed ferry, fitted with two S160-S4L jets plus two S100-S4LB boosters, the first commercial S-4L installation.
- April 2026: India contracted 18 large Kamewa jets for the Navy's Next Generation Missile Vessels at Cochin Shipyard, paired with GE LM2500 gas turbines, which Kongsberg calls its largest waterjet order ever, per The Defense Post; per-unit size and order value were not available.
- January 2026: HamiltonJet opened a 7,500 m2 Christchurch factory with 50 percent more floor space, after breaking ground on 27 June 2024; the site has 430 employees, with manufacturing headcount rising from 187 to about 220 at full capacity.
- 2026: Thrustmaster of Texas acquired Doen's waterjet technology and plans a 400/450 series extending Doen-designed jets up to 6,400 kW.
- Indonesian Navy KCR-70 fast attack craft pair twin Promas CPPs for patrol speeds with a single Kamewa waterjet booster for high speed.
- A Korean fireboat with dual MJP 850 DRB jets was scheduled for delivery in January 2025; no further confirmed MJP order for 2025-2026 was found.
Outlook
Thrustmaster's planned 6,400 kW series is a US bid for the mid-size steel-jet class historically held by Kamewa and MJP, likely motivated by naval and Jones Act demand. No independent recent efficiency curve comparing modern waterjets with propellers was found; the crossover figures above come from vendor or decades-old technical sources.
