Yarrow blamed the new job losses on a gap in the order book, despite the fact that the yard won a pounds 400m order in February from the Ministry of Defence to build three Type 23 frigates.
When the redundancy programme was first unveiled in February ahead of the announcement of the Type 23 order, the company hinted that 1,000 jobs or more might have to go unless the Type 23 came to Yarrow.
But now the threatened total has been reached even with the order in place.
A spokesman for Yarrow said today: "We always said there would be a second batch of redundancies. We thought that would be in April, we have managed to hold it off until May."
Of the total to go, 490 manual workers and 80 staff and managerial employees are affected, mainly from the production side.
The workforce at the yard will have reduced from 2,900 at the beginning of the year to 1,900 in three months' time. A Yarrow spokesman said: "In the longer term we'd like to recruit people again."
Yarrow is owned by GEC which last year took over the VSEL warship yard at Barrow. GEC gave assurances that it would keep both yards open.
George Kerr, a convener at the yard, said unions were warned during the last round of redundancies in February to expect many more jobs would go because of a gap in the order book and in ship building programmes.
"We were told to expect hundreds of redundancies and hundreds we have received. The mood is depressed, heads are down and morale is low. Everybody is just low in spirits."
He did not expect the jobs situation to improve at the yard until next year.