Hunt Design - Waterjets

Hunt Designed Boats with Waterjet Propulsion

Hunt designers have been working with waterjets for nearly 40 years. During that time we have watched them improve and develop to become a major player in marine propulsion. Waterjets solve a basic problem for much of our waterfront; navigation in shallow water and water that is congested with pot buoys, submerged logs and other nasty stuff that can destroy conventional underwater gear.

Waterjet boats are extremely maneuverable. They can spin on a dime, but controlling their maneuverability can be frustrating for first-time users. Because you are directing 100% of the thrust, a small adjustment to the helm can mean a big change in direction, and so it is harder to keep a nice straight course. The new fully integrated joy-stick and mouse-type controls can be a help, especially when docking. Jets can be more efficient than propellers in higher speed ranges, 35–50 kts, but less efficient down at 15–30 knots. (For very high speeds, surface piercing propellers have the advantage.)

Deep-V hulls are the best match for jets. The deep-V’s combination of a long, deep afterbody and shallow, cut-away forefoot give it inherent directional stability, whereas flatter-bottomed hulls with sharp bows tend to skid around or dig the forefoot in and broach.

"Jet" jet drive launch by Goetz

Hunt deep-V’s have less trouble controlling course-steering when equipped with jets. To go a step further, we have developed our own special trim tabs for jets that add directional stability and counteract the tendency of jets to suck the stern down both at slower speeds and in the transition from displacement speeds to planing. A Hunt deep-V with waterjets can be driven hands-off and she will hold course upwind and down, and with seas on a stern quarter. Try that with some other jet boats!




1970: 32' Offshore Raceboat This boat was designed for Castoldi to have two race prepared gas V-8’s powering one waterjet! We designed a simple 2 into 1 transfer drive using the same drive belts then being used in the first front-wheel-drive big Oldsmobiles and Cadillacs. The boat was campaigned in Europe.				1970: 21' Production Built Runabout This runabout was designed for Solcio of Italy. It was based on our HiLiner 21 design. Power was exotic for the time, a double overhead cam 4-cylinder Alfa Romeo engine coupled to a Castoldi waterjet.



1973: 25' Surfhunter "Qien Sabe" This Surfhunter was built by Fairhaven Marine. Powered by a 203hp Caterpillar 3196 V-8 diesel coupled to a Jacuzzi stainless steel 14YJ waterjet. These were the same units used by the US Navy in its riverine patrol boats in Vietnam. This was a big and heavy propulsion system for a small boat. To save weight, we built a cored hull in an early use of Airex foam with little other structure. Top speed was 32 knots. Last heard from, the boat was living in Maine after many years with her original owner.				1977: 25' Surfhunter "Khronos" This Surfhunter 25 was built for a Maine man who wanted a picnic boat that would not snag pot buoys. She was a center console boat that carried a Dyer dinghy on rollers aft.
				Powered by two 6-cylinder Mercruiser gas engines and Jacuzzi waterjets, she was designed to take owners from their home to offshore islands. The dinghy would be launched, and they would row ashore with their picnic basket onto one of the many uninhabited Maine coast islands. Khronos was the first jet picnic boat in Maine!



1976: 32' Custom Day Boat "Contrail" This boat was built by Chester A. Crosby & Sons of Osterville, MA, for a Cape Cod family’s general summer use. Another lightweight Airex-cored hull based on an earlier raceboat hull with only 9’-6” beam, sport fishing-style sheer and full deadrise, Contrail was a great sea boat. Still in service, her original Jacuzzi jets and high output V-8 gas engines were recently replaced by Yanmar diesels and Hamilton jets.				1981: 87' Patrolboat This early large waterjet boat was one of the first cored FRP boats built to ABS rules. Hunt Design and Airex AG of Switzerland were pioneering the development of large, light, fast
				craft. This Thai-built boat made 27 knots with three, 1000 hp Isotta Fraschini diesels and Castoldi waterjets. This design was copied by others and, ironically, the US Navy nearly bought several from Israel as they had a good reputation in the military for performance.



1987: 36' High Tech Launch "Jet" This boat built by Goetz was appropriately named by her owner, who wanted a fast launch to take him to his lodge and private island on the Lake of the Woods in Canada. The lake’s snags and peat islands just below the surface were tough on the props on his Bertram, so a waterjet was the obvious answer. The design				1996: 36' NSW RIB We designed this boat for the US Special Operations Command. These large RIBS are built in FRP by Willard Marine and are now being built in large numbers. Power is twin 370 Cummins diesels and Hamilton jets for a top speed of 38 knots.
was limited by a boat house - both for size and weight. Forty knots was the speed goal. The answer was a very high-tech lightweight structure by Goetz, modified 425 hp Volvo diesels and Hamilton waterjets. Finishing touches included custom aircraft seats, upholstered with custom dyed leather and arranged theater-style so all aboard could have a good view.



1998: 107' Aluminum Motor Yacht This Italian-styled yacht built by Palmer Johnson was the first boat to carry the largest waterjets made by Hamilton. With 1800 hp 16-cylinder MTU diesels, “Mostro” made 30 knots on her large Hunt deep-V hull.				1997: Honda PWC Hunt Design won a contract with Honda R&D to test several existing PWCs and develop a new prototype some years before Honda brought a PWC to market, using their superior 4-cycle engines. This was an extensive project that lasted one full summer and into the winter while we tested and built an all new PWC out of parts from another, of course incorporating a new Hunt hull. This is the smallest jet project we have undertaken to date.



2004: 70' Pilot Boat This vessel, built by Gladding-Hearn Shipbuilding, was designed for the Galveston, Texas pilots, who have since ordered a second vessel of the same kind. This boat uses Cummins KTA 38, 1300 hp diesels and Hamilton 571 waterjets and operates at a service speed of 30 knots.				2008: 64' Screening Escort Vessel Owned By the US Navy and operated by the US Coast Guard, this series of 12 vessels built by Gladding-Hearn Shipbuilding is designed for naval asset protection and search and rescue. They incorporate Hunt’s latest design thinking, and the newest waterjet technology. Even
				before the full production run was finished, the boats gained a fine reputation for their speed, ride and handling.



1990 - Present: SeaArk Marine A major builder of aluminum patrol boats based in Arkansas, SeaArk builds a range of Hunt designs from 18 to 85 ft., and many use waterjet propulsion.				1999 - Present: Hunt Yachts We have built several jet boats at Hunt Yachts since our start in 1998. These include a single-jet 33, twin-jet 36s, a single-jet 29 and others. While we see waterjets as an
				attractive propulsion option for many yachting requirements, it is certainly not the only one. Given our considerable experience with waterjets as well as with all other propulsion options, we can recommend the right configuration for our clients.