Pump it up!: Water jets are no longer used just for thrill-seeking jet-skiers. Now larger boats in a variety of applications are using the technology for propulsion — so what's powering the trend?

THE FIRST THING that may come to mind when you think of water-jet propulsion is the jet skis that are popular with holiday-goers and adrenaline junkies. Traditionally the system has been used in small vessels such as these and the jetboats used by coastguards, the navy and others. Since 2000, however, this technology has increasingly been used by larger vessels such as military ships and ferries. But what makes water jets (also called pump jets) appeal more to operators in these fields than traditional propellers?