The pride of the South African Navy enters Durban Harbour today for a four-day visit that will give taxpayers the chance to go aboard the vessel they paid for, after all the controversy that surrounded their purchase.

The visit by the SAS Mendi, the last of the navy's four Valour-class frigates to be delivered, which arrived from Germany in September, is part of an operational training cruise before naval contractors begin to fit the ship with armaments and the electronic warfare system in Simon's Town.

The four - SAS Mendi, SAS Amatola, SAS Isandlwana and SAS Spioenkop - are closely associated with KwaZulu-Natal by virtue of their names, which, Cdr Brian Stockton, a navy spokesman, said celebrated courage in adversity and battle - of the victors and the vanquished.

The vessels are a big step up for the navy which, for many years, has had to rely on strike craft that were not designed for the rough conditions off the South African coast but nevertheless did an admirable job to help protect the country's marine assets.

They also pack a significant punch, use stealth technology and other features that will make them a valuable acquisition and provide South Africa with a blue-water capability for years to come.

Possible roles for the vessels could include helping to patrol South Africa's sea lanes and its economic exclusion zones, particularly around Marion and Prince Edward islands, 1 700km south of Cape Town, where stocks of the Patagonian toothfish are on the verge of collapse because of poaching which has cost the country at least R3 billion since 1996 through potential lost revenue.

"Poaching was one of the main reasons behind the acquisition of these vessels and we'd like to see them stem the tide of illegal poaching," said Deon Nel of the World Wide Fund for Nature.

Not particularly fast for a warship at 27 knots, the frigate's stealth capabilities, which reduce the radar, acoustic and infra-red signatures of the ships, nevertheless, would come in handy, in an anti-poaching role.

Such features, experts say, would greatly lend themselves to making an effective arrest at sea, because, under international law, vessels fishing illegally can claim "innocent passage" unless caught in the act.

More likely roles for the frigates would be operational training visits to other countries, supporting peacekeeping missions and guarding South Africa's sea lanes. The stealth abilities of the Valour-class ships are achieved in part by an uncluttered deck, angled hull panels and by the elimination of the funnel.

Instead, the ships' exhaust gases are water-cooled before the fumes are expelled just above the waterline from the rear of the ships.

The SAS Amatola has the name of an Eastern Cape mountain range where a major battle was fought between the Xhosas and British Army at the turn of the 19th century. The Anglo-Boer War, fought on the banks of the Tugela River, gave rise to the name SAS Spioenkop.

SAS Isandlwana commemorates those who fought at Isandlwana, where Lord Chelmsford's forces suffered a crushing defeat by Zulu impis during the 1879 Anglo-Zulu War.

The SAS Mendi is named after the troopship that sank on February 21 1917 while carrying the South African Native Labour Corps to France during World War 1.

Rammed in thick mist off the Isle of Wight by the liner SS Darro, the Mendi sank within 25 minutes of the collision and claimed about 650 lives.

Among the dead were several Pondoland chiefs and the Rev Isaac Dyobha, who was said to have rallied the men by saying: "Be calm, my countrymen, for what is taking place now is what you came here to do.

We are all going to die, and that is what we came for... Let us die like warriors. We are the sons of Africa."

Heeding his call, the sons of Africa sang and performed a war dance as the ship slipped below the waves.

The sinking was one of the single worst blows to South African forces in World War 1, possibly only second to the loss of 2 400 soldiers who died defending Delville Wood during the Somme offensive of 1918.

Nevertheless, the acts of valour on the Mendi's deck have lasting recognition, both in the warship that bears its name and in a national award, The Mendi Decoration for Bravery.

For his part, Dyobha had a navy strike craft named after him - possibly the only naval ship in the world to be named after a cleric

The SAS Mendi's visit to Durban was the first by one of the new vessels, but it certainly would not be the last, Stockton said. The contractors who would fit the vessel with its armament and guidance systems were not ready to start work on the Mendi, which allowed Capt Kevin Packer to take his pride and joy on a training cruise to evaluate the vessel's performance in South Africa's different harbours and to show it off.

Packer said that his ship - which is powered by a combination of diesel engines and a gas turbine-driven water-jet propulsion system - was very stable and had excellent crew's quarters, unlike the strike craft which he served on for five years while operating out of Durban's Salisbury Island.

When complete, the four ships' main armament will be eight Exocet surface-to-surface missiles with a range of 70km - similar to the ones used with devastating effects by Argentina during the 1982 Falklands War.

Sixteen Umkhonto surface-to-air missiles, each with a 23kg warhead and a range of 12km, four torpedo tubes, a 76mm cannon upfront, two 20mm cannons and two 35mm double-barrelled guns - controlled through a formidable fire-control computer - complete the frigate's firepower.

The SAS Mendi will be open to the public at N-shed, on the T Jetty, from 10am to 4pm on Saturday and Sunday, and will leave for Simon's Town, via Port Elizabeth, at 6pm on Sunday.

With acknowledgements to Greg Hutson and The Mercury.