Lars Landelius, The Swedish Club's Salvage Master, said: 'The central issue here is that navigating in the open ocean is less demanding than safe passage up or down a river with strong currents and many hazardous shallows.

The exposure to a grounding or other incident is obviously increased when the vessel is fully laden in both directions.'

One example is the busy stretch of the Orinoco to Puerto Ordaz, around 200km upriver.

It is commonplace for vessels to enter the Orinoco in a laden condition, discharge at Puerto Ordaz, load another full cargo and then make the return voyage downriver. There are strong currents of up to 4 knots in the rainy season.

Last December a 37,500dwt bulk carrier was proceeding fully laden with 30,000 tonnes of steel briquettes down the Orinoco when she grounded on a sandbank halfway downriver.

The vessel is entered with the Club for Hull & Machinery cover. Fortunately there was no significant bottom damage and no pollution. The vessel was promptly refloated by local tugs.

More recently. a 38,000dwt bulker was less fortunate, running aground fully laden near an anchorage close to the Orinoco port of Matanzas. In this case the grounding site was rocky and substantial bottom damage resulted. There was no pollution and the vessel, entered with the Club for both hull and P&I, was refloated immediately by local tugs. The incident resulted in repairs costing $500,000, including the replacement of 100m 2of bottom plating.

Lars Landelius added: 'The Orinoco is not special, in the sense that many of the world's largest rivers present a range of hazards, particularly for vessels fully laden. In some cases.

dredging programmes and the maintenance of navigational aids may not be adequate. The answer is to recognise the condition of the river, stay alert at all times - even when the pilot is on board - and recognise the special demands of river navigation.'

MJ Information No 16822