Last year, Doen WaterJets restructured, ownership returned to the company founders and investment in research and development was revived. This has spawned a new range of waterjets with a direct thrust option at its heart, a repackaging and phasing out of some existing models, and an upgraded and expanded series of electronic control systems.
With direct thrust, the main shaft is arranged to thrust directly to the gearbox, like a conventional propeller arrangement. The waterjet shaft line uses a conventional propeller shaft seal and connects directly to the gearbox output coupling, allowing for compact installation without the need for intermediate shafting. The absence of a thrust bearing system on the waterjet itself supports simple and economical maintenance. Another selling point of the direct thrust system is the compact design, which is likely to appeal to designers struggling with space in the machinery compartment, or seeking to move the low centre of gravity further aft in the vessel.
The company has also focused on re-packaging the established range to appeal to the small- and medium-size workboat market.
The new DJ172 (impeller size 432 mm) and DJ152 (impeller size 381 mm) waterjets use Doen’s existing impeller technologies that have been a feature of the company’s DJ170HP and DJ140HP waterjets for more than a decade. The difference between the models is the intake duct design and the installation method.
The reference list for the revamped DJ172 includes European, American and Asian operators.
Doen cites a 19.4 m passenger ferry, driven by twin Volvo D13-700 diesels coupled to DJ172 waterjets. The vessel now has a top speed of 38 knots and requires only low power for sustained cruise speeds at full load.
When it comes to control systems, options range from simple hydro mechanical to Doen’s latest electronic control packages. They can be installed as single units or as multiple jets - a quad DJ152 set being installed in an eco-tourism catamaran, currently under construction in Canada.
To complete the transom-mount product range, the DJ112 waterjet will shortly be introduced to replace Doen’s bestselling product, DJ110; although the DJ110 is being phased out, Doen Waterjets will continue to offer service and support to existing customers and for all discontinued Doen waterjet products.
Doen WaterJets has also updated its ECS400 electronic control system. The next generation ECS400 runs on CAN bus technology and benefits from enhanced computing power. It is compatible with an expanded range of third-party systems such as autopilot, bow thruster or remote control systems in autonomous applications.
All Doen WaterJets models in single or multiple installation can be configured with ECS400, which provides for waterjet steering and reverse control, engine throttle, gear select, as well as backup, alarms, indication and auto calibration in a fully-integrated system.
For budget-driven builds the ECS-lite system is being marketed as a simple and low-cost electronic control, combining the engine and throttle control by way of single double-function lever. It also provides for gear select and alarm functions.