Hemi Anisi goes to work with a gun - and a wary outlook for pirates.
The ex-New Zealand army soldier is certified by the International Marine Organisation (IMO) to defend ships and crews with lethal force.
He has fired several times to warn offshore-based "pirate skiffs".
Crewed by armed men, these craft are cautioned over marine radio if they come within 800m of the ship.
"And if they ignore the warnings and come within 400m we'll fire over their heads, which is usually enough to dissuade them," says Mr Anisi.
"Obviously we're aboard a big ship - with plenty of cover - while they're in small boats and maybe in ocean swells. It's very hard for them to take aim accurately.
They haven't really got a chance against armed defenders, and usually warning shots are enough to make the point. I've seen fire returned, and even a rocket-propelled grenade fired from one of the pirate skiffs, but that [projectile] did not even hit our ship, thank God."
Mr Anisi and his colleagues are committed to preventing pirates taking over ships or harming crews, but he has nothing personal against the pirates he's faced.
In the Gulf of Aden, he encountered men quite unlike the career buccaneers he read about as a child growing up in Henderson, Auckland.
Unlike "Long John Silver", "Billy Bones" and "Captain Flint", Somali pirates turned out to be ragged young fishermen. Mr Anisi says they were probably unable to make an honest living after the collapse of their economy and drifted into crime.
"We learned that they don't like foreigners, because traditional fishing grounds had been poached and cleaned out by the big international trawlers, while remaining fish stocks were scared away by international shipping just off their coast. They're tempted into kidnapping ship crews for ransom."
Mr Anisi has worked alongside ex-New Zealand military personnel like himself in marine hotspots around the world. His first postings, or "transits", were in the notorious Strait of Malacca between Malaysia and Sumatra, where pirates have long been known to board ships.
But rather than aiming to kidnap the crew, as in Somalia, it has been to rob, or even murder.
Mr Anisi retrained in retail management after leaving the army. Then a friend asked him to help in anti-piracy work in the Strait of Malacca.
At first he worked while on leave, before gaining IMO qualifications in maritime security. He got jobs in South Asia, then guarded pipe-laying barges in the Gulf.
He was based in Yemen, working alongside a dozen ex-NZ servicemen. The men joined ships which passed through the the Red Sea and Gulf of Aden, getting on board when there was a perceived threat from pirates.
"They set us up in a villa which was quite comfortable; we'd drive or fly out to join big tankers or container ships travelling both ways.
"Most ships allowed us to carry weapons but, depending on the flag [country of registration], some wanted unarmed security. If we weren't allowed to carry weapons, we'd 'harden' the ship with razor wire, add steel plating to withstand small-arms fire and assemble pyrotechnics and flares to use just in case.
"On every ship, we instruct the crew on what to do in the event of a pirate attack. We ensure that a ship can be disabled if it is boarded by pirates and establish a citadel [panic room], usually below the engine room, where the crew could lock themselves in and be safe."
New Zealand ex-military are well regarded in maritime security. "We don't have the high-tech weapons," Mr Anisi said, "but we're seen as more disciplined than nationals from some other countries. We're valued as able to work without complaining, above all because we get along with people of any and all cultures."
Much of the challenge is to keep a lookout during 24-hour watches, using radar and binoculars. If need be, extra lookouts might be drafted in from the crew of the ship.
Mr Anisi and his Kiwi comrades hire the firearms they need, depending on what is available in the country concerned. These are kept under lock and key when not aboard.
He says favoured weapons include shotguns, AK47 or M4 assault rifles and - a particular favourite of ex-Kiwi servicemen - a modern version of the self-loading rifle (SLR).
Mr Anisi's current job is managing security on a large oil rig off the coast of Kenya, in an area that has been plagued by armed criminals.
Colleagues patrol around the rig in small boats while he generally stays on board. The Kenyan navy also keeps its own watch - employing a zero-tolerance policy against pirates.
Mr Anisi says numbers of operators involved in maritime security have increased vastly in recent years. Prices have fallen and more Filipino nationals are employed.
"These men are usually ex-marines and they make quite good personnel, but do need to be trained," he says.
"It looks like piracy will always be with us in unstable parts of the world.
"I've been fortunate to work with maritime security companies working to high standards. The challenge will be to maintain these standards; we must keep cowboy operators out of the industry."