Jurmo-class is a fast and agile military transport vessel designed and built by Marine Alutech, a boat builder based in Finland, for landing and transporting troops in all weather conditions. It is referred to as the Watercat® M12 by the builder.
The vessel has been in service with the Finnish Navy for more than 20 years. It is being improved with advancements to its control system and user interface.
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The improvements will allow the vessel to conduct amphibious assaults in shallow waters, offer higher reliability and strengthen the capabilities of coastal armed forces, especially in the harsh conditions of the Baltic Sea region.
Jurmo-class landing craft design and features
The Jurmo-class landing craft’s hull and deck are made of aluminium. It has an overall length of 14.25m, a beam of 3.65m and a draught of 0.70m. The low draught makes the vessel suitable for amphibious assaults in shallow waters. Weighing 10.4t, the vessel displaces 13.8t of water.
The vessel’s fore deck features 20 cushioned seats with seat belts, while a lightweight composite cover provides shelter. The cover features hatches and a hydraulically operated bow ramp which ensures quick cargo and personnel loading and unloading.
The landing craft is equipped with state-of-the-art marine electronics and communication systems, ergonomically positioned to facilitate the skipper’s safe and comfortable operation, even during challenging military missions.
The vessel ensures a low noise level of less than 75dBA [a-weighted decibels]. It can also be outfitted with two 12.7mm machine guns for military and patrol purposes.
Waterjets and control systems details
The improved landing craft will be equipped with a pair of Kongsberg Kamewa FF375 aluminium waterjets and a compact electronic jet control system, replacing the initial mechanical-hydraulic system.
The impeller, shaft and steering or reversing rods of the waterjets are made of stainless steel, while the remaining components are made of aluminium to minimise the overall weight. The pump is designed with a single-stage axial-flow configuration, offering a high-volume flow and excellent pulling thrust across a broad range of speeds.
The FF375 waterjets feature a tailored inlet duct, allowing the new craft to closely replicate the performance attributes of the original Jurmo-class vessels that are currently in service with the Finnish Navy. The Kamewa aluminium series waterjets encompass power ratings ranging from 100kW to 2,000kW.
The compact jet control system ensures precise and reliable management of hydraulic valves within the waterjet system, utilising integrated feedback signals. The system, along with waterjet propulsors, facilitates seamless control of steering and reversing, while signals related to engine throttle and clutch are managed by external devices.
Performance
The vessel sails at a maximum speed of more than 35 knots (kt) and a cruising speed of more than 30kt, while the range is more than 180 nautical miles.
The Kamewa waterjet reversing system offers the ability to bring a vessel to a complete halt from its maximum speed within the span of just one ship length.
Jurmo-class landing craft orders and deliveries
In July 2023, Marine Alutech signed a contract worth €25.5m ($27.8m) to deliver 17 Jurmo-class landing craft, along with the necessary spare parts, to the Finnish Defence Forces. The acquisition aimed at sustaining and enhancing the mobility of coastal troops through the deployment of the new Jurmo-class vessels through the 2030s.
The addition of the vessels will increase Finland’s landing craft inventory to more than 50.
Contractors involved
Kongsberg Maritime, a subsea company based in Norway, will supply the Kamewa waterjets for the 17 new landing craft to be built for the Finnish Navy.
