Key Points:

A South Korean coastguard vessel, powered by the largest water jet propulsion units ever produced in New Zealand, has beaten all target speeds during sea trials, says the Christchurch-based manufacturer HamiltonJet.

HamiltonJet - whose parent company CWF Hamilton & Co was founded in 1939 by Sir William Hamilton - said the first pair of water jets, which took two years to develop, were delivered early last year.

Sea trials took place in November and the units entered service in a 55m Korean Coast Guard patrol vessel.

Global sales and marketing manager Mike Shearer said the Korean Coast Guard had more than 120 vessels fitted with HamiltonJet water jet units.

"However, a much larger water jet than those in the existing product range was required for this project, to allow the vessel to patrol at over 20 knots on the outer jet units alone," Shearer said.

The 300-tonne Korean vessels are fitted with two of the new water jet units - each of which pump 11cu m of water a second at full speed - and a pair of smaller booster jets.

All four water jets are driven by 3700 horsepower engines and provide a maximum speed of more than 36 knots, or 66km/h.

Company spokesman Tony Kean said each set of four jet units was worth about US$1 million ($1.97 million), with four sets already shipped, orders confirmed for another three this year and negotiations underway for three more sets for next year.

Water jets had advantages of manoeuvrability and a shallow draft capability, Kean said.

"They could be in deep water or shallow water, and with the jets you're guaranteed that you're not going to loose a propeller or bend a rudder or anything like that which would affect the boat's performance," he said.

The jet stream is used to power and steer the vessel.

"A lot of smugglers these days start dropping nets and ropes and things off the back to try and deter the chase boats, but it's not a problem with jets."

The company, which had a turnover of more than $60 million in its last financial year, employed about 300 people at its Christchurch manufacturing base, with the recreational market harder hit by the global recession than commercial business.

"Definitely the work is down in the factory, and we've had to relieve some of our temps but we're hoping that we've hit the bottom now," Kean said.

"Put it this way, we've got a lot of good enquires and good sales leads that we are pursuing."

The recreational market accounted for less than 5 per cent of business, with products also sold into the work-boat market, including pilot boats, crew supply, passenger vessels and patrol and rescue boats.

The company had opened a Singapore office, and Asia was seen as a key market during the next few years, he said.

The new jet unit was a major product for the company, which was still owned by the Hamilton family, Kean said.

"Because it's a new product and a larger one, it's given us as much as anything a real good-feel factor that we are still leading the way in terms of the development of water jets."