Canada's chief shipbuilding official has announced an update, nearly a year after the federal government chose the Halifax Shipyard to build warships and arctic patrol vessels worth more than $25 billion.

The Irving Shipyard will start the project by building between six and eight arctic patrol vessels. It is still in what is known as the "project definition" stage.

Commodore Patrick Finn, director of the National Shipbuilding Procurement Strategy Office, told participants at the Canadian Defense Security and Aerospace Conference Friday he realizes people think the government should be moving faster on contracts to design ships, so that materials can be ordered and workers trained.

The first steel isn't scheduled to be cut for another three years.

"If we were cutting steel right now it would not be a good thing because we would be cutting it against an incomplete design," said Finn, "and that's pretty much a guarantee for waste and rework."

How many arctic vessels get built will depend on the cost and final design. Irving engineers are now reviewing the government's preliminary design as part of a process to avoid skyrocketing cost overruns plaguing projects like the Cyclone helicopters.

Getting the patrol vessels started will require another contract to finalize the design and drawings from which the ships will be built.

"Right now our broad target would be to have the more detailed definition contract in place next year," said Finn.

As for the second set of ships — the 21 combat vessels — Finn said Ottawa is in the early boarding stages of determining how big the ships will be and what type of equipment they will carry.