Jet Setters

Waterjets continue to make inroads in the workboat arena as potential customers in the government and commercial markets become more aware of this alternative to the traditional prop, rudder and deep-keel power setup. 

Take the Coast Guard, for example. They will soon begin replacing their 41’ response boats with new 44-footers, 180 of them, all powered with waterjets. 

Kvichak Marine Industries in Seattle built one of the three response boat-medium prototypes that are being considered by the Coast Guard. Kvichak’s boat had Kamewa FF375S waterjets hooked up to Series 60 Detroit Diesels, rated at 825 hp each. (The other two prototypes, built by Textron and OTECH, are powered by waterjets from Kamewa and HamiltonJet.) 

Kamewa waterjets also push a pair of 235’ Alaska Marine Highway System ferries, the Fairweather and the Chenega, both built by Derecktor Shipyards in Bridgeport, Conn. 

This is the first time an Alaska state ferry has used waterjets, said William Sall, sales manager for Rolls Royce Commercial Marine in Seattle, manufacturers of Kamewa. These are not small jets. The intakes measure almost 3’ in diameter.

The waterjet-powered catamarans are proving their worth, according to the ferry system’s Web site, as the two ferries have the “highest transport efficiency of any high-speed ferry of this size.”

Four large Kamewa waterjets also propel the U.S. Navy’s high-speed X-Craft, now undergoing testing in San Diego. Since 9/11, the military has provided a lot of business for boatbuilders and manufacturers of waterjets. Kvichak Marine, besides competing for the Coast Guard RBM contract, also has an order from the Navy for 10 40’ ×14’ utility boats. The boats will be used for beach support work, and each is being outfitted with a pair of 364 waterjets from HamiltonJet. The jets are hooked up to 666-hp Cummins Marine QSM11 diesels. 

This is the first installation of the 364 HamiltonJet in the U.S. An important feature of the 364 is the shaft alignment. Instead of being restricted to a 5º shaft alignment, as are the company’s other waterjets, the 364 is available with a 0º shaft alignment. That puts the shaft parallel to the waterline, which allows the engine to be mounted lower in the boat and makes installation easier.



Something else that’s new from HamiltonJet is the Blue Arrow electronic control system. Previously, the controls were mechanical or hydraulic. Blue Arrow is a fully integrated control package. 

For maneuvering, Blue Arrow uses what they call a “mouse boat” because the control looks like a boat, said Bruce Woodfin at Atlantis Marine Gear Supply, a HamiltonJet dealer in Topsfield, Mass. 

“Push it sideways and the reverse buckets and nozzles do what needs to be done to make the boat go sideways,” he said. It’s the same for heading in other directions. Woodfin said the mouse boat “is real easy docking or maneuvering around objects.” 

But with the rpm and the jet’s bucket control on the same lever, Woodfin said Blue Arrow might not work as well for a pilot boat as other workboat applications. “Pilots like separate levers so they can raise the rpm as much as they want at zero boat speed and keep the buckets down,” he said.

In New England, Atlantis Marine is finding more interest in waterjets from RIB operators. In one case, the company just put a pair of 292 waterjets from HamiltonJet into a 40-foot RIB, built by Gladding-Hearn of Somerset, Mass., for the pilots association in Charleston, S.C. 

The waterjets were matched up with 405-hp Cummins Marine QSL9 engines and Twin Disc MG-5075SC marine gears with 8:1 reduction ratios. That propulsion package gave the RIB a top speed of 33 to 34 knots. The boat was delivered in late November. 

The Charleston pilot boat was the “first commercial RIB of that size,” that Atlantis Marine has supplied with waterjets, Woodfin said. 

Another sector of the workboat market that’s paying more attention to waterjets is eco-tours. 

Graham Scott, president of Ultra Dynamics, Columbus, Ohio, builder of the UltraJet, said, “Recently there’s more active interest in waterjets by owners of excursion and touring boats, especially whale watching.” One advantage of jets, he noted, is that whales and seals won’t be injured if they get too close to a waterjet, like they could if they get near a prop. 

The newest waterjet from Ultra Dynamics is the UltraJet 575. The company’s waterjets are known for operating in speed ranges between 15 and 35 knots. The UltraJet 575 stays within this range but is designed for boats carrying heavier loads than could be accommodated with the UltraJet 451, the next size down in the UltraJet lineup. 

Scott didn’t want to elaborate, but an UltraJet 650 will be introduced in the near future. “That will put us in the 2,000- to 2,200-hp range,” he said. The UltraJet 575 is about 1,800 hp. 

Sometimes waterjets can drastically exceed expectations. That’s what Ultra Dynamics found on a 70-foot pilot boat outfitted with UltraJet 451s that was built by Horizon Shipbuilding in Bayou La Batre, Ala. The boat is now operating in Iraq.

With twin Caterpillar 3406E diesels and ZF350 marine gears, Scott reported that the boat went slightly more than 24 knots, topping its contract speed by six knots.



Waterjets can also be adapted to the “unusual” applications. Take the case of North American Marine Jet in Benton, Ark., a company known for its low-speed (down to 10 knots) high-thrust Traktor jets. North American Marine recently supplied the waterjets for a dive boat operating out of Dubai in the United Arab Emirates.

That’s not dive boat as in passengers going snorkeling or scuba diving. It’s dive as in a submersible. “It’s was a pretty neat idea, but we never thought it would come about,” said Jason Hill, president of North American Marine Jet. 

But it did and the boat is carrying a pair of North American Marine TJ-864HT waterjets with 34” impellers. On the surface, the jets deliver about 600-hp of thrust and run off diesels, which are also running an electric motor that acts as a generator to charge a bank of batteries. 

When the boat dives, the jets are running off the batteries and horsepower drops to 175. The boat is designed to operate 30 meters below the surface. A big hurdle to overcome was designing a fuel system that could operate at the pressures developed at that depth.

Another case of waterjet adaptability for North American Marine was a pair of 18” Traktor jets that went into a RIB in Norway this past summer. The specs called for the boat to go 34 knots but also have a 10,000-lb. bollard pull. “Basically it was a towboat and a rescue boat combined,” Hill said. 

Because of the RIB’s 21º bottom, if the 18” Traktor jets were put in individually, the jets and their steering systems wouldn’t fit and would overlap. So Hill and his crew designed a single housing that “made two jets into one. You still had two intakes, but it was built in one piece,” he said. With everything on one skid, it was relatively easy to install in the boat. 

About the author

Workboat Staff

Leave A Reply

© Diversified Communications. All rights reserved.