A Sea Change in Waterjet Technology

By Joseph Keefe

Longtime waterjet propulsion equipment provider NAMJet introduces key advancements for the workboat sector.

Back in 2011, when boat builder Birdon went looking for a propulsion system that they could utilize in the bid phases of a multi-boat contract with the U.S. Army, they landed on NAMJet propulsion systems and its TRAKTOR Jet line of high-thrust marine jets. Subsequent to that, and because their Army Bridge Erection boat (BEB) concept, powered by NAMJet, performed so well, Birdon went ahead and purchased the company. Since then, NAMJet has gone on to blaze its own trail for propulsion solutions over a wide range of workboats.

Denver-based NAMJet provides waterjet technology designed for a wide variety of commercial, military and workboat applications, fully customizable to meet the standards of the world’s most demanding operators. Today NAMJet offers propulsion systems for engines in the 150–850-horsepower range, and stands ready to deliver the next generation of advanced marine propulsion with its newly developed RAPTORJet range with both electric and hydraulic options.

RAPTORJet & iNAV Unveiled
Last month, NAMJet introduced a new range of RAPTORJet waterjets. These feature – and NAMJet says it is the first time ever for this type of propulsion – iNAV electric actuation which eliminates the need for hydraulic tanks, valves, oil, hoses, maintenance and potential oil leaks. In world where the EPA’s VGP keeps vessel operators up at night, this feature alone will make potential customers sit up and take notice.

In a nutshell, iNAV is a comprehensive set of electronic controls spanning conventional throttle and joystick control, all the way through to glass helm operations. Beyond this, says NAMjet president Ian Ramsey, the iNAV system can provide remote updates and upgrades with predictive maintenance and data logging capability. The firm’s recently produced 10 meter demonstration workboat features two of the newly designed RAPTORJets, and made its debut at Seawork 2016. There, potential customers were able to witness firsthand the power and improved thrust of the jets. The demonstration boat was built by sister company Birdon America and eventually will be based at a NAMJet facility in the U.K. and used for various exhibitions around Europe.

On that boat, the innovative RAPTORJet RJ431e propulsion system is matched with a Cummins’ 6.7-liter QSB engine rated at 480hp and a ZF 301-1c transmission. Ramsey characterizes the new equipment as “a sea change in waterjet technology,” adding, “The demo boat RAPTOR achieved 39 knots at altitude in fresh water. We expect it will do 42 knots at sea level and have a bollard pull of at least 4.2 tons, which is massive.”

According to NAMJet, RAPTORJet is the first waterjet worldwide to provide the option of electric actuation, eliminating the need for hydraulic pumps, oil tanks, filters, plumbing, ongoing hydraulic maintenance and potential oil leaks. Raptorjet has been specifically designed to accommodate electric actuation, however a hydraulic option is also available. The introduction of the Intelligent Navigation & Control System (iNAV) is a fully integrated electronic control system, compatible with most navigational hardware and sensors. It can be configured as a basic system to control engine throttles, transmission, jet bucket and steering up to the iNAV-iN5 system providing joystick control, an intuitive user interface for navigation and full vessel control on a touch screen glass helm. The control features station keeping and dynamic positioning capability, as well as multi-vessel positioning control from a single vessel.

The main control box is located in the helm and handles all of the high level commands such as GPS headings and sonar. There is also a jet controller located near the waterjets which handles all the lower level commands for steering and bucket control. Notably, there are no bundles of cables running down the boat between the waterjets and the helm control panel. It is simply connected via an Ethernet Cat 5 cable so installation or refit for boat builders is much easier than running streams of cables.

NAMJet describes their waterjet design as a ‘smooth riding, instantaneous response with no chatter.’ Ramsey explains simply, “Hydraulic systems, whilst being very reliable if well maintained, do have a slight delay and slop in the command signals from the steering and bucket control system. Simply put; the electric actuation system is instantaneous which allows for smooth quiet ramping.” Beyond this, the RAPTORJet produces massive thrust at 700-110 RPMs, whereas the competition needs 3,000 RPMs to duplicate the same performance. 

“Our waterjets are of mass axial flow design, which relies on the volume of water passing through the intake. The impeller rotates at a very low speed between 700 – 1,150 rpms which is highly efficient in producing enormous thrust and little to no cavitation from idle up to 35 knots,” said Ramsey. The feature potentially allows customers to use smaller engines, which might be incorporated into an EPA ‘tier buster’ propulsion scenario. Ramsey adds, “Generally, our waterjets operate a lot more efficiently and can produce significantly higher thrust than high speed jets, which allows for the use of small power plants (on some occasions).” 

Value Added to Target Markets
NAMJet, like so many other marine operators and OEM providers, is also on board with the world of ‘big data.’ A data logging feature – essentially a black box feature which records numerous real time operating parameters – provides fundamental data including accident investigation and is also useful as a training tool. The system can also be fitted with a predictive maintenance capability which potentially increases uptime for vessels and can avoid equipment issues before they happen. 

As wind power develops offshore and finally gets its sea legs here in the U.S., NAMJet’s newest entry to the workboat propulsion market is positioned to compete. Ian Ramsey explains, “NAMJet’s higher thrust capability and little-to-zero cavitation provides wind farm crew transfer vessels with a much higher transfer limit window which means the CTVs can stay engaged longer with the wind farm towers in greater sea state conditions,” adding, “There is a growing trend with windfarm operators that the need for greater speeds and larger power plants to drive larger jets is not necessarily the best possible solution for these type of operations. Our studies have proven that by going to a quad waterjet solution has many advantages over larger twin waterjet operations. Quad waterjets provides full redundancy and given NAMJet’s higher thrust capability, it is possible through the use of the iNAV control system, to power cycle the jets to maximize fuel economy and reduce wear and tear whilst connected to a wind farm tower.” 

Track Record: Looking Back, Thrusting Forward

No stranger to the competitive bid process, Birdon’s successful route to build U.S. Army BEB’s went through 600 hours of extensive testing at Aberdeen. In November of 2013, it was announced that Birdon America – the American subsidiary of Birdon Australia – had in fact won the competition and was being awarded the contract. Those boats included two Traktor Jet 381s – NAMJet’s smallest jet, commercial off-the-shelf units. In the end, the Army decided that NAMJet was the only propulsion system that could satisfy both speed and thrust requirements for this type of project.

The very nature of the work required of the new generation BEB also involves toiling in riverine, sometimes highly turbid and muddy, debris choked waters. That means that the propulsion systems for these shallow draft craft must not only be durable, they’ve got to be able sustain prolonged service in unfriendly waters. According to NAMJet, that’s exactly why they were chosen. 

NAMJet’s Ramsey told Marine News in June, “The industry has seen very little innovation and change in recent years [beyond electronic control systems for throttle, helm and joystick controls]. We see the introduction of electric actuation and the capability for autonomous vessel control as the beginning of a profound transformation in technology that will deliver improved thrust and performance; a more cost effective and value for money proposition for vessel owners.” 


(As published in the July 2016 edition of Marine News)

Marine News Magazine, page 47,  Jul 2016

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