The Liberal government has decided to pull out all the stops on the construction of the navy's planned permanent supply ships — a move that's raised questions about how quickly the Canadian Coast Guard will get a critical oceanographic science vessel.

Public Services and Procurement Canada (PSPC) issued a statement Tuesday that announced the re-sequencing of the construction schedules for vessels being built at the Vancouver Shipyard, which is owned by Seaspan.

The company has already started preliminary construction work on the first of the navy's long-awaited Joint Support Ships and the federal government says the work will continue until the vessel is completed.

Under the National Shipbuilding Strategy, Seaspan was suppose to first construct three small fisheries research ships and a larger oceanographic vessel before working on the navy's long-awaited supply ships.

Adhering to that plan in the face of repeated organizational delays meant delivery of those supply ships — which are considered critical to allowing the navy to operate beyond Canadian shores — would not happen until 2023 at the earliest.

The PSPC statement said that once the first supply ship is finished, Seaspan will turn its attention to the coast guard oceanographic ship and then build the last planned naval supply ship.

"Given the complexity of this build, this change in sequencing will ensure focused engineering resources on each of the projects, while allowing for time between construction of the first and second [Joint Support Ship] to incorporate lessons learned," said PSPC spokesman Pierre-Alain Bujold in a statement.

"Moreover, this allows for uninterrupted work at the shipyard, mitigating the risk of potential layoffs and production gaps between builds."

Bujold said additional details on the construction schedule will be released at a later date.

The change to the schedule was, according to sources in the defence industry, agreed upon at the recent Trudeau government cabinet retreat in Sherbrooke, Que.

Rob Huebert, a defence expert at the University of Calgary, said the decision "leaves most people scratching their heads" because of the difficulty involved in getting a shipyard to switch up construction between different types of vessels.

"Why you would interrupt the building of ships by putting another style and class of vessel in the middle completely boggles my mind," said Huebert, a noted expert on the Arctic. "I don't know why you would do it."

If anything, he said, the federal government should simply build both naval ships and then move on the coast guard ship.

The re-sequencing means the navy could be waiting until the late 2020s for its second supply vessel, which would make the program a multi-decade odyssey.

The Liberal government of former prime minister Paul Martin originally ordered the replacement of the auxiliary ships in 2004, but the program was cancelled in 2008 by the Conservatives when cost estimates exceeded the budget envelope.

Huebert said Tuesday's announcement also raises questions about when Canadians will see the heavy icebreaker that Seaspan is also slated to build.

The PSPC website says the program is under review and "no activities are planned until work on other projects has advanced."

The federal government apparently has not yet formally notified Seaspan of the schedule change, although the shipyard has awarded a series of sub-contracts to companies such as INDAL in Mississauga, Ont., and L3 MAPPS in Montreal, for supply ship components.

Seaspan is expected to announce another contract on Wednesday with Lockheed Martin Canada related to the supply ships.

Ever since the Conservatives cancelled the first iteration of the supply ship project, the federal government has struggled to get it back on track, setting and missing several deadlines.

The supply ships were supposed to arrive in 2017. The date was pushed back to 2019, and then to 2022. The absence of a supply ship prompted the Davie shipyard, in Levis, Que., to pitch a converted civilian cargo ship for navy use.

That $668 million lease deal is at the centre of the breach-of-trust case against Vice-Admiral Mark Norman. Davie is pitching the federal government on leasing another cargo ship.

A spokesman for Davie, Frederik Boisvert, called Tuesday's decision "an insult to taxpayers" and claimed that Seaspan has failed to deliver on the supply ship project and "should be blacklisted by the government and not rewarded for failure."

The effect of switching up the schedule means the navy might not need a second supply ship leasing deal.

Sources within the coast guard and the defence industry have said that the design and project coordination for the fisheries science vessel is not as far advanced as the navy supply ship program and that is an important factor in the federal government's timing decision.