Patrick, who was this morning rubber-stamped by a joint sitting of state parliament as Nick Xenophon’s SA Best senate replacement, is at pains to emphasise that he renounced his dual nationality before nominating to fill the casual vacancy, left by his former boss and party leader.

But he considers the citizenship crisis engulfing the federal parliament “an unwanted distraction”, declaring: “I hope that we get this stuff out of the way relatively quickly.”

“It doesn’t go to the merit of the people in the parliament,” he told InDaily of the furore over inadvertent dual citizenships.

“Some of these senators and members – people like Barnaby Joyce, he’s a quintessential Australian… people ought to be concentrating on merits.

“I respect the constitution, I respect the High Court…but I think the constitution is wanting for change in relation to citizenship.”

Further, he believes section 44 needs a broader overhaul, taking issue with the exclusion of people who hold an “office of profit under the crown”.

Commonwealth employees must first relinquish their employment before nominating to run for parliament – the loophole that has put the appointment of Liberal Hollie Hughes as a replacement for dual citizen Fiona Nash under a cloud.

Patrick argues the requirement is a deterrent for potential quality candidates, and says while he will not champion a referendum himself, “it’s something I’d support if it came up”.

Nomination as Senator for SA formally approved at joint sitting of SA Parliament.Holding official documents that NZ citizenship is renounced pic.twitter.com/tDtEVj2d3Z

— Rex Patrick (@MrRexPatrick) November 14, 2017

His immediate focus is on several issues he believes are “much, much more on South Australian [voters’] minds” – energy costs, an effective naval defence program and “proper implementation of the Murray Darling Basin Plan”.

A former submariner – who also gave unpaid industry advice to former Liberal defence spokesman David Johnston when he was in Opposition – says he wants to ensure the shipbuilding program is done “effectively and efficiently – with as much Australian content as possible”.

He is concerned at the prospect that foreign tenderers for the $30 billion Future Frigates program will have no obligation to utilise domestic shipbuilders ASC and Austal for the construction work.

“We have two sovereign Australian companies… that have been excluded from a lead role in the Future Frigates program – that’s quite disturbing,” he said.

“We’ve built up those two companies and now we’re going to bring in a foreign company… we need one of those overseas shipbuilders for the design work, but we’re quite capable of building the ships in our own yards.

“I’m concerned about the organisation of it, from my own defence experience.”

That experience is extensive: Patrick left Whyalla to join the Navy, where he became one of six people posted to Adelaide as part of the initial Collins Class submarine crew.

He eventually left the Navy “because I could see a lot of problems with Collins”, and went into private enterprise designing sub sonar systems.

After publishing numerous articles on the future submarine program, he worked pro bono for Johnston, then shadow Defence Minister, developing strategy around the subs issue.

He turned down an offer to advise the Abbott Government on submarines, before joining Xenophon instead.

Patrick is adamant revisiting the tender requirements would not derail the frigates project.

“There’s still time – the reality is we could select the designer under current tender arrangements and nominate an Australian builder – ASC or Austal – and that will not cause a delay,” he said.

He echoed recent comments to a senate inquiry from ASC chair Bruce Carter that the subcorp had developed its own people, culture and systems, adding: “No other country in the world runs a frigate or warship program and excludes their own national shipyards from participating in a lead role.”

Patrick says he remains on good terms with Johnston – ironically, given Xenophon was one of the fiercest critics of the former minsiter’s infamous remarks questioning ASC’s construction credentials, when he asserted they could not be trusted “to build a canoe”.

“If there was any hope of privatising the ASC for a reasonable price, it is just gone. The government is trashing it,” Xenophon said at the time.

Patrick says now Johnston’s outburst was “an unfortunate comment”.

“A rhetorical flourish, I think they call it… I think he regrets making that comment.”

Patrick is already technically a senator after this morning’s state parliament vote, but he will be formally sworn in to federal parliament tomorrow morning.