This year, 510 unemployed teen-agers in New Zealand will get a taste of military life. The youths, between the ages of 17 and 191/2, will join the Army, Air Force, or Navy for 20-week courses aimed at teaching them skills that will help them find work after graduation.
The ''limited-service volunteer'' program was drafted by the government to counter a growing unemployment problem among teen-agers, who account for one-third of the nation's 78,000 jobless. More than 5,000 of the total jobless are youngsters who have just left school.
Among the first to sign up was Judith Garmonsway of Wellington, who had been out of work for a year. ''I'm sick of being on the dole,'' she said.
The service volunteers will be paid about $40 a week, the amount they would draw in unemployment benefits.
The youths will take the same medical, educational, and aptitude tests given to normal rookies, wear military uniform, and be subject to full military discipline - including short haircuts. But they will not receive weapons training.
Instruction will include preliminary trade courses such as cooking, storekeep-ing, auto maintenance, and welding. At graduation, volunteers will receive a certificate of service, including an assessment of conduct and abilities that may be useful to a potential employer.
The Defense Ministry was cool to the plan at first. It did not consider job training to be a role of the armed services. But its objections have been overruled.
The military does not expect the youths to become career soldiers. In fact, all three services have cut back on recruitment. With unemployment at 6 percent, more soldiers are staying in the forces instead of quitting for civilian jobs.