Breaking the piracy "business model" and tackling Somalia's onshore problems will be among the aims of a major international conference on Somalia in London on Thursday. But few are optimistic of a solution any time soon, and shippers say they must take matters into their own hands.

Greater use of private armed security guards on ships and a much tougher approach by international navies is beginning to work, some mariners, officials, contractors and military officers say. But others worry they may simply fuelling a growing arms race, ramping up the conflict and producing a rising human and financial cost.

In March last year, Alibasic was transporting a cargo of crude oil from Sudan to Asia when his tanker - the 100,000 ton United Arab Emirates-registered Zirku - came under attack. For 90 minutes, the pirates poured heavy machine gun and rocket propelled grenade fire into the vessel.

Then they were aboard, swarming over the two levels of barbed wire that surrounded the decks.

The ferocity of the initial onslaught, he says, was matched by much of the treatment suffered by him and his 28 crew during their 75 days in captivity.

As the shipowners negotiated the payment of an unspecified but reportedly "massive" ransom, he did everything he could to keep the multinational crew - including Jordanians, Egyptians, Ukrainians and Pakistanis - safe from sometimes drugged and bored captors.

"I read them poetry and played them opera to try to calm them down," he said, adding that he also played chess with the pirate leader "Abdallah" to win his respect. "But they nearly hanged my second mate."

The unlucky second officer's only offence, he said, was to have demanded the right to have a shower after spending hours working in the tanker's sweltering engine room. By the time Alibasic persuaded the pirates to let him go, the rope was already around his neck.

Seafarers' organizations say the treatment of prisoners has worsened over time. Other sailors have been suspended hung upside down for hours, dumped overboard or even keelhauled - dragged under the ship from one side to the other on a rope, a traditional punishment of the age of sail barely reported since the 17th or early 18th centuries.

Estimates suggest at least 60 seafarers have died.

When the pirates forced Alibasic to sail back out into the Indian Ocean to rescue some of their stranded colleagues, he found himself on the receiving end of a new set of naval rules of engagement.

On one of his trips, his tanker came under fire from the U.S. Navy.

"I got on the radio and said: "What are you doing? They (the pirates) will kill us all ... They were using us as human shields," he said.

About 25 warships from various nations now patrol the Indian Ocean at any given time.

Some states - such as Russia - have always adopted an aggressive approach when their ships were hijacked, storming them with force and either killing the pirates or leaving them to die in open boats. The United States has also launched special forces missions to rescue its nationals.

Other Western states - particularly the Europeans who make up the bulk of EU and NATO-led task forces - were initially more cautious. But even they have started to take a tougher stance, engaging pirate "motherships" and retaking captured vessels.

Many commanders have welcomed the new approach, saying it is behind the slump in successful pirate attacks in the second half of 2011. Only 25 ships were seized in 2011, the European Union Naval Force Somalia (EU NAVFOR) says, compared to 47 the year earlier.

Pirates now hold six ships and roughly 176 hostages, the EU says, again well down from last year.

But average ransoms continue to rise - now about $5 million compared to $4 million last year.

Estimates of the cost to the global economy are also up - one report put it at $7 billion in 2011.

The fastest growing component of that, the US-based Oceans Beyond Piracy report said, was the cost of the rising number of armed private security guards. At the beginning of 2011, they estimated perhaps a quarter of ships carried such guards, rising to an estimated half now.

Shipping companies spent roughly $1 billion on private guards alone in 2011, the report said - much more than the estimated $160 million earned by the pirates themselves in ransoms.

Many piracy experts - including serving naval officers - believe it was the private guards who made the real difference against piracy in 2011.

But the unregulated industry raises a host of new worries.

A 2011 UN report details one incident, in which naval forces rescued a damaged skiff containing one dead Somali and six survivors, who said two other compatriots had also been killed and had fallen overboard.

Naval observers concluded gunfire had come from illegally-held weapons on a ship recently attacked by the skiff, but were unable to provide definitive proof.

"It's very likely people are being killed out in the Indian Ocean by private guards and it's not being reported," says Rory Lamrock, piracy analyst at UK-based risk consultancy AKE.

A former military officer himself, tanker captain Alibasic worries over the moral and legal implications of dispensing lethal force from the deck of a civilian merchant ship.

But he also has a more immediate concern - will the guards he now carries on his voyages through the region have enough arms and ammunition to fight off the kind of concerted assault he faced last March?

As to solving the wider problem of Somali piracy, he says that is something that will only happen when the world gets seriously involved onshore in the pirate havens of Puntland and elsewhere.

"When we had a war in Croatia, we did not become pirates," he says, referring to the Balkan wars of the 1990s. "The international community and the UN came and things were sorted out in only a few years. That's what needs to happen in Somalia."