Sea-floor gold miner Seafield Resources, which has offshore seabed permits stretching 500km from Karamea to Jacksons Bay on the West Coast, hopes to begin a full test programme next summer.
Seafield has been held up almost 18 months as it designs and develops a range of new drilling systems, including a continous 10m core sampler, a stronger drill launch and recovery system and a buoyancy compensation system to keep the drilling ship stable - all understood to have cost Seafield several million dollars to date.
South African mining family the Oppenheimers are majority shareholders in Seafield, whose partner in the venture is marine diamond mining specialist De Beers Marine, a subsidiary of De Beers Group, at present in African waters.
Dunedin-based geo-scientist John Youngson, whose company, Placer Solutions, floated the undersea gold project to De Beers Marine and is a consultant to Seafield, said three onshore tests of the Wellington-made drilling system had gone well.
A sea trial is planned off Nelson's coast next summer, followed ideally by the first 40-60 day sampling programme within the permitted West Coast area later in the summer to make the most of settled weather patterns.
"The drilling system has been refined [since the onshore tests] but is otherwise working well," Mr Youngson said.
Because of the high cost of operating the test rig from a ship, its operation had to run "like a finely tuned Formula 1 pit crew", Mr Youngson said.
The test drill design incorporates seven-inch bits to take geological samples and 13th-inch bits for mineral sampling.
"The systems' designs and testing is what has been the hold-up for the past 18 months," Mr Youngson said.
Seafield's two prospecting areas, granted licences from October 2006 until October 2010, cover a total of more than 10,000sq km offshore and extend to beyond the 12-mile limit and include drilling in depths up to 120m.
The firm is targeting gold swept into the sea by glaciers and rivers over thousands of years but which was now trapped in sand and gravel on the sea floor.
Seafield has to date carried out 4000km of airborne magnetic surveys and two ship-based geophysical surveys totalling 2400km off the West Coast and commissioned several independent environmental studies, including the effects of the venture on marine mammals.
About 10 million ounces of alluvial, or loose placer gold, has been recovered in the past 145 years from West Coast beaches and rivers.
Mr Youngson said the results from the earlier airborne and geophysical surveys provided many initial target areas to explore, including post-glacial channels, submerged shorelines and glacial outwash deposits.
"There's no shortage of targets and we won't get to them all," he said of the proposed summer drilling programme.
The present four-year exploration permits and licences held by Seafield, which are due to expire in 15 months, could be extended if if applied for three months before the October expiry.
