Two 12-m chase boats aboard the Australian-based mega yacht Arctic P has been successfully converted from stern drives to waterjet propulsion. Hamilton Jet, local jet distributor Wiltrading Pty Ltd.
and boat builder Stebercraft Pty Ltd.
worked closely to retrofit the craft as quickly as possible.
The first of the two chase boats, which are deck mounted on the 288.7 ft. (88 m) Arctic P, was urgently converted late last year, when one of the chase boat's stern drives with surface piercing props broke down again.
Waterjets were mentioned as a possible solution, so Hamilton Jet's New South Wales distributor Wiltrading was contacted. After assessing the requirements twin Hamilton Model HJ292 waterjets were recommended as the best option to go with the original 370 hp Sabre engines. The order to modify was given in early November 2000.
The short time-span available for the conversion meant Hamilton Jet
had to source the waterjets and intake blocks from its extensive worldwide distributor network. Two HJ292 jets were diverted from a shipment to the United States, while matching intake blocks were sent from Western Australia and Seattle.
The chase boat was road-transported 350 km north from Sydney to Stebercraft Pty in Taree for the shipwright work. This included partially removing lifting strakes, increasing the engine room length by removing and rebuilding the transom, fitting the waterjet intakes and new engine bases, mounting the waterjets and adjusting the steering ratio. GWB drive shafts and Centra damper were also installed.
In 22 days the modifications were complete, preliminary trials were carried out and the boat was returned to the owner for official "handover" trials and final commissioning.
Peter Iredale from Wiltrading was on the boat during these trials and says everyone was extremely impressed with the change. Comments were made about the ease with which the boat got onto the plane, lack of cavitation and the tight turning circle achieved at speed, and quieter and smoother operation throughout the full speed range.
The Master of Arctic P and those who knew the chase boat in its original stern drive configuration were also impressed with the excellent maneuvering abilities provided by the twin Hamilton Waterjets. These include 360-degree on-the-spot rotation and direct sideways movement. Top speed was 38 knots, which was slightly less than the stern drives, but this was more than compensated for by less noise and vibration, greater maneuverability and steering response, ease of control, and subsequent reliability.
After using the "new" chase boat for eight weeks over the Christmas period, the decision to convert the second 12-m chase boat to Hamilton Waterjet propulsion was made and an order placed. Unfortunately the very short delivery achieved with the first vessel was not possible for the second boat, and after a slight extension on the original scheduled delivery, the second boat was delivered back to Arctic P in June 2001.