Doubtful Sound & Manapouri Power Station- Part2

Continuing on from Part 1

After poking our nose out into the ocean our boat then followed the south side of the fiord back towards the wharf turning down the long and narrow Crooked Arm quietly inching it’s way across the still water and tucking up in a small narrow cove near the end where the boat turned off its motors & we were all asked to hold still & quiet for a minute or two to listen to the sounds of nature. No camera clicks, no walking, no talking, no movement……wait, who is that stomping up the deck!

No it wasn’t David but he did have something to do with it. David was having a very expensive conversation. Instead of looking at the beautiful scenery of Doubtful Sound he was inside, engrossed in a discussion with an American couple, John & Diane,who we had sat near when we first boarded the boat. John was an ex-fighter pilot and David was in his element talking planes. David & John had been so focused on talking that they had failed to hear the announcement to be quiet & still. And then when they had noticed the quite they wondered what was going on…wondered in loud voices. They were suitably told to shsssh by the captain. Then John, not realising that he was meant to be still too, stomped off up the deck to find Diane & was frowned at by staff all the way. John & David had a little giggle about that, John said he felt like a naughty schoolboy!

The reflections on this part of the fiord were wonderful.

Leaving our “quiet" spot I overheard a few people saying how amazing they found that experience and it was, the bird noise from the bush surrounding us was of constant singing & chattering, something like I imagine the bush used to be before introduced predators decimated our native birds. Nearby a small waterfall gurgled as it entered the fiord and that was it, the rest was the sound of silence. 

This is known as a tree avalanche. The rainforest mostly cannot get a good root hold in the thin layer of soil & leaf mould & hangs precariously to the steep granite rock of the mountains. Tree avalanches are usually triggered by high rainfall or snow.

The Fiordland fiords are famous for their waterfalls but with no substantial rain for weeks a lot of them had dried up. Manapouri village receives 1 metre of rain a year but over at West Arm the rainfall rises to 4 metres and at Deep Cove it reaches 9 metres. As this rain makes its way into the fiord via streams, rivers & waterfalls it becomes the colour of weak tea, stained by the tanin and other matter from the forest floor. The tanin stained water is less dense than sea water & forms a layer on the surface that floats and only partially mixes with the salt. This gives the fiord its dark inky appearance and it’s where one of the largest colonies of black coral in the world live. The coral, which is usually found at depths of 60 metres or more grows at just 8-10 metres, it is tricked into thinking it’s deep water by the thick layer of freshwater which filters out the light.

Passing a small bush clad island on our way back to the wharf.

There were a few private launches visiting the fiord and  a number of fishing boats that are based in Doubtful tied up at the wharf.

 

The buses await our return.

 

We were taken on a small detour to check where the two 10km long tail-race tunnels from the power station that exit from under the mountain and into Doubtful Sound.

As promised, with the cloud now lifted, the bus stopped at the top of the pass so we could see the Sound in all it’s glory.

Back down at West Arm we took a side road up to the entrance of the power station tunnel, a 9 metre wide tunnel that spirals its way 2 kilometres underground to the Machine Hall.

The seven huge blue machines on the hall floor are exciters. The exciter stimulates the rotor of the main generator below it to produce electricity. It’s hard to get a sense of the size of these, it would have been great to have someone in the picture but have a look at trolley forklift to the left. The room is 18 metres wide & 39 metres high. The exciters are huge but below them on the stator floor are even larger generators & transformers. And below that floor is the turbine floor, the turbine shaft spins at 250 revolutions per minute. This is where the water comes in from the penstocks(the blue tubes in the station mock up) to drive the turbines. Above the turbine shaft is the generator. Water travels through the penstocks at a combined rate of approx, 500 cubic metres per second (500 tonnes per second)

Up on the surface the bus took us back to the terminal & our waiting boat, David & John still chatting away!

So what else could we do but invite them back for drinks which then turned into dinner. We had a lovely evening and quite a few laughs. It was great meeting you Diane & John, until next time, cheers!