Lake dive for engine just another day at the office

Bill Day (left) and Dr Simon Mitchell during the dive for Haast pilot Morgan Saxton's helicopter engine. Photo by Toby Wallis.
Bill Day (left) and Dr Simon Mitchell during the dive for Haast pilot Morgan Saxton's helicopter engine. Photo by Toby Wallis.
Sir Edmund Hillary's famous phrase "we knocked the bastard off" continues to echo for generations of adventurers, and none more so than deep-sea diver Bill Day (51), of Wellington, and soon to be of Wanaka.

Top on his list of "bastards" is the wreck of the General Grant, which sank in the treacherous waters off the Auckland Islands in 1866, reportedly with a large cache of gold on board.

Now, Mr Day, the founder of Seaworks Ltd, has added the missing engine from the late Morgan Saxton's Robinson 22 helicopter to his list.

A 74m retrieval attempt last weekend by his friend and colleague, Auckland deep-water diving specialist Dr Simon Mitchell, is believed to be the deepest dive in the lake.

A second attempt is to be made this weekend.

Retrieving the engine is something Mr Day wants to do for his newly-adopted community and the Wallis family, which is spearheading the retrieval attempts.

Getting the engine back would have meaning for Mr Saxton's family and friends, as well as help Transport Accident Investigation Commission inspectors complete their report into the November 1 accident, Mr Day said.

"The reality is, I am a recent arrival and very junior member of the community and it is nice to be able to give something back," he said.

Mr Day and his wife Karen intend to move permanently to their Mt Barker home after their youngest son finishes school this year.

In November, navy and police dive squads refused to put a diver 74m below the lake surface because regulations did not allow the use of mixed gases.

But they could not afford a commercial-scale exercise with decompression chamber and dive bell.

Nevertheless, the navy and police were able to retrieve Mr Saxton's body and some pieces of helicopter using a remotely-operated vehicle and a "Kiwi number-eight wire" hook invention by local diver Brent Pihama.

Recent changes in breathing apparatus computer technology meant the deep dive could now be done recreationally by skilled divers, without the costs of a commercial operation, Mr Day said.

The Saxton engine dive required the same research and planning as a treasure hunt, before Dr Mitchell was sent down, Mr Day said.

In the Auckland Islands, the water was not so deep but it was cold, remote and rough.

The challenges in Wanaka were the depth of the lake and the altitude, putting extra pressure on Dr Mitchell.

He carried a mixture of helium and oxygen in tanks, with three different computer systems mixing it.

If the computers "disagreed" about the gas mixture, they were programmed to go with a "majority decision".

If that system failed, Dr Mitchell had a manual mixing system with him.