Ironsand drilling adventure +Photos/Video

Just 20km out to sea and it's a different world.

Mt Taranaki is no more than a sizeable pimple in the distance, streaked with the first snows of winter, and the rest of South Taranaki is a mere smudge on the horizon. Safety depends completely on the strength and skills of a small vessel and its crew, and we are a tiny speck in the vast ocean.

The boat moves constantly so this landlubber has to brace herself or grab something to stay standing. The sea is heaving in great long swells. They're only a metre or two in height but they cause the ship to sway from side to side. Within the swells are small, white-capped waves.

The water is a deep blue this far out, and utterly clear. Birds are the only life to be seen, mainly big flocks of cape pigeons, a species of petrel, floating on the surface to feed or skimming the waves in flight.

It took a 40-minute trip in Stratford dairy farmer Eddie Jenkins' fishing charter boat to get here. Stepping from one boat to another, while both were in motion, was carefully done.

We're aboard to watch the crew of the Island Leader II drop a rig through 30m of water and drill just one test hole into the sea floor. It will be one of many in a grid pattern across kilometres of coastline, from Pihama south of Opunake to the Rangitikei River.

The drill rig is at the stern of the boat. It's a type patented by Pat Cooper, the owner of Cooper's Drilling Services, and pioneered on the Antarctic ice. Cooper is aboard and he explains that it comprises three cylinders in one. The outer contains compressed air that shoots a path into the sand for the drill. The next contains compressed water. Sand from the sea floor is pulled up through the third space, the drill's hollow centre.

The spot where the drill goes down is marked using a global positioning system (GPS) and an undersea camera sends images back to the ship's bridge.

The drill goes 9m deep, and as the sand is pulled up on to the deck it is bagged in labelled sacks, one for each of the nine metres. Sometimes the sand is rattling with pebbles. The contents will be analysed at Trans-Tasman Resources (TTR) in Porirua.

TTR geologist Max Watt is on the bridge. He says the black sand particles that contain iron are called titanomagnetite. That on the South Taranaki coast is vanadium-titanomagnetite (VTM), a valuable commodity.

The proportion of VTM in the sand can be measured using a magnet. Watt puts a magnet to the steel cap of his boot, and gets a reading of 89. If the steel in his boot was solid you could expect a reading of about 200. Some of the sand has a reading of 400.

But nothing is certain. The iron content of the sand varies across TTR's prospecting and exploration areas. So is the depth of sand that covers the sea floor's mudstone basement rock.

The Island Leader II's eight-member crew includes four divers. At times they've directed some of the drilling from the sea floor. They say the water is clear down there and the bed is an endless surface of black, rippling sand, with occasional boulders and not much else.

Iron-rich particles have been carried there by river systems draining Mt Taranaki and earlier volcanoes. The richest area for iron is right where we are, 22km off Hawera.

It's a fearsome coast to work on. The Kupe petroleum platform 6.5km away is just visible and is mostly not staffed for good reason.

Weather offshore is different. During a dream summer of light winds and fine weather on land, the Island Leader crew have had about 60 per cent down time, because of the weather. When it gets rough their safety is compromised, and the drill rig could be damaged. They either lay up in calmer water, berth at Wanganui and amuse themselves with movies or trips to the gym and pool, or head out of town until it clears. On board they can watch movies or do a bit of fishing usually for blue cod. They have limited personal space but the galley with padded bench seats is comfortable and skipper Luke Ogilvy is a good cook.

Diver Gavin Graham is the only Wanganui man in the crew. He can tell them where the fishing is good. That was mainly further inshore or near the limestone reefs, the North and South Traps, "but we don't go near them".

All sea life is logged, a condition of the exploration, but there hasn't been much of it. A seal, seen once, and no dolphins in the 18 months Ogilvy has been there.

When the weather is calm the crew work 12-hour days. Even with that length shift they can drill seven holes at most.Little wonder it has taken years to cover TTR's exploration area.

But all that testing is drawing to a close. TTR intends to apply for mining consent this year so the results of the drilling and the surveys of environmental effects need to be handed in as soon as possible.

Consultant Frank Boffa is along for the day. He's been asked to assess the visual effect from land of large ships mining offshore, and also the effect of a plume of sand on the offshore waters.

The closest the mining would get to land would be about 13km, and he thinks the ships will be visible only on a clear day, and not very visible at that. The effect of a plume is a different matter. It could turn the sea a different colour, perhaps the milky green of coastal water that is mixed with sediment washed off the land.

The South Taranaki Bight is a horrible place to work, the crew say. They've drilled only two holes so far this morning and by mid-day the weather begins to pack up.

"This wasn't a good day, but it was good enough for us to get out and have a go," one of them says.

They have to motor back to find enough calm for the visitors to transfer onto the boat that ferried them out.

The trip back hugs the coast, so Boffa can see the effect of sediment in the water. The entrance to the Patea River is hard to distinguish along a coast of forbidding cliffs and promontories. The landing is easier than the departure though, with rollers carrying the Hy-Jinks II smoothly in over the Patea bar.

It's a relief to step ashore into a fine autumn day with light breezes and all is well with the world - so different from the buffeting offshore.