"He put it into a controlled descent but unfortunately we had no land to land on so it had to be the water,'' he said.
"We don't call it a crash; it's a controlled landing. Crashes are when they fall to bits.''
The helicopter floated for two to three minutes, giving the pilot and passenger plenty of time to get out, before it sank.
Mr Pike said it was the first helicopter of its kind.
"It's the world's first Composite helicopter, made totally in New Zealand, apart from the engine which appears to have been the downfall of it.''
The engine was made in America, he said.
"This is pretty much the first New Zealand-made serious helicopter there is.''
Mr Pike said the two men on board were uninjured, while police said they had minor injuries.
A Navy spokeswoman said the inshore patrol vessel HMNZS Taupo happened to be sailing from Devonport Naval Base at the time of the incident.
"It was very much in the right place at the right time to provide rapid response to that emergency.''
Auckland Westpac rescue helicopter pilot Barry Watkin saw the splash as the chopper landed in the harbour.
"There was an almighty splash as the rotor blades hit the water .''
He said a second chopper was accompanying the one that crashed, and hovered over the location.
Something "catastrophic'' had occurred with the chopper that caused it to drop into the water.
The pilot was able to make a mayday call and performed a "semi controlled'' crash where the chopper turned on its side, which killed the rotor blades and allowed him and a passenger to escape uninjured.
It was submerged under a metre of water.
Mr Watkin said it was extremely unlucky thing to happen - but those on board were also incredibly lucky to walk away uninjured.
"I'd be going straight to the lotto shop.''
The pilot of the crashed helicopter, Peter Maloney, told reporters engine failure was the cause of the crash.
He saw a warning light and then heard an audible warning which told him , "I was losing power''.
