The prime minister has arrived in Perth for a two-day visit ahead of the May 21 election, promising his government will continue to grow the defence industry if re-elected.

He says about 400 direct jobs will be created under the $124 million investment in two new Evolved Cape Class patrol boats, as well as a further 150 in the supply chain.

The vessels will be built by Austal at the Henderson shipyard near Fremantle, adding to the six vessels it is already delivering there.

"This investment doesn't just help secure our borders, it secures hundreds of shipbuilding jobs in Western Australia," Mr Morrison said in a statement on Monday.

"More shipbuilding work means a strong economy, and a stronger future for this important industry and our Navy and Australian Border Force."

Mr Morrison used a pre-election visit to WA, where Labor is targeting several marginal seats, to announce the development of a $4.3 billion dry docking facility at Henderson.

The government is spruiking a local shipbuilding pipeline worth close to $30 billion through to 2040.

WA's Labor government had lobbied hard for the state to build Australia's new nuclear-powered submarines given the existing Collins Class subs are based in WA.

A decision was instead made to build the submarines in South Australia.

Defence Minister Peter Dutton said the new patrol boats would contribute to fisheries protection, immigration, customs and drug law enforcement operations.

"These extra boats will also enable Navy to transfer two of its Cape Class patrol boats to the ABF - further strengthening our border defences," he said.

WA-based Defence Industry Minister Melissa Price said it was a shot in the arm for the shipbuilding industry.

The two vessels are scheduled to be delivered by late-2023, with all eight to be operational by early-2024.

Australian Associated Press