Criminals often come back to the place of the crime scene. Divers too.
Maybe some of you remember the starting of this blog. In Episode 1, the project started on a small mountain lake in the south-tyrolian Alps more than two years ago. End of september this year we went back to this place to go diving and to survey this lake with better equipment than we had used when we went there for the first time. The this year crew consisted of three persons:
Bernhard, Hermes and me. Thanks to the boss of the local fishing club, this year, we had a permission to drive to the "base" camp, which is situated at the end of a valley in 1800m above sea level. Two years ago, we also went there, but without a permission, there is still some thrill in the air...
So, we started on thursday afternoon to a 5hour trip across the alps with roughly 300 kg of equipment with us.
We arrived at the base camp in the evening and were welcomed by the host of a small alpine bar - Konrad-. We knew him from the last trip, when he managed to fill us up with some kind of a local brandy, that left deep impressions in our brains and livers. This year i was aware of that and stopped at glass #2. Sometimes it is hard to say no, but "failure tells a man how to succeed".
The next morning we prepared for the first ascend to the first lake, which is some 400m above the base camp.
Bernhard, the boat-sherpa
Diving is not really a sport in terms of power, endurance as other sports are - preparing to dive is!
The sunday before, i ran my first marathon and had still some muscles that remembered me on some points of this 42km journey. Anyway, we started the ascend with roughly 20kg per person in our backpacks. We arrived one hour later at the first lake more dead than alive. 2300m above seal level can be really challenging, when no sherpa blood is running through your veins.
The recovery went amazingly fast, maybe by the help of some amount of beer, we carried with us. Arrived on the lake, we assembled the catamarane and first did a "manual" survey to get the outline of the lake. For that purpose, Hermes swam around the lake with a body-board and carried the catamarane and the GPS-sonar behind him.
Hermes, swimming, with the boat
In the meanwhile, i prepared the mission for the ArduPilot. The correlation between the measured shoreline and the Google-Earth data showed, that there was nearly no difference.
The path for the ArduPilot was quickly drawn, converted and downloaded to the ArduPilot.
The point of no return
Where the hell does the ship go?
This was the first question we asked, when the boat went off-shore. The path was something like "reversed", but the boat did its job well and after 30 minutes it stoppped the motor - on the opposite side of the lake! -
Fortunately, it stopped in shallow water, and the recovery was done by wading and not by swimming.
What had happened?
I used Google Earth to draw the path for the boat and the map was oriented north-up. Because i am not really a genius in orientation, i managed to draw the path in the wrong direction. The start was located on the north-end of the lake and i thought we were on the south-end. Anyway, the boat did its job and this time i was not the one to recover the boat!
After this (nearly) perfect survey, we took all the stuff to 2500m above sea level to the second lake, which is much smaller than the first one. The weather got worse and the temperatures went down to nearly the freezing point. This time we did no pre-survey and took the shoreline data directly from Google Earth.
Hacking on 2500m ASL , the servo and me, -shivering-
The only thing that made me nervous, was the fact, that the rudder servo shivered heavily, when at standstill. I thought, that there was a loose contact somewhere in the wiring. What to do, when you are at 2500m and you have no tools with you? -Nothing-
So i decided to launch the boat and luck was on my side. It paved its way perfectly and came back to the starting point. It went so good, that i decided to make a second round. Also absolutely perfect. Later analysis showed, that the servo i have used had trouble with low temperatures. Now i use a digital type and this one works also at temperatures below the freezing point. The weather went worse and so we decided to bring all the survey equipment down to the base camp. After a short stop there, we took our backpacks and went back up to the lake, this time with the diving equipment. The plan was to deposit the tanks and all the other heavy stuff on the lake and go further up to an alpine cabin, which should be our second base camp for the night. We arrived there in the night, totally exhausted, but happy. After some plastic cups of beer and some eating we felt into a deep and dreamless sleep. The weather forecast announced rain and i was happy not to hear any raindrops on the rooftop. Sometimes the forecasts are wrong -good-. Early in the next morning i opened the door and then i suddenly realized, why i heard no raindrops...
The whole area was covered with a 30cm thick layer of snow.
This fact put an early end to our dive mission on this day... and this year.
So we took all our bearings and went down to the lake, where we have deposited the equipment. Where the hell has Hermes put the tanks, the regulators and the weightbelts? It took us half an hour to find the place under the snow.
The diving equipment - finally recovered-
After that intermezzo, the sun came out and we had an excellent descent down to the base camp in a bizarre winter environment.
Down on earth, i did a lot of DrDepth-ing and produced this nice pictures from the lake:
The path on Lake #1
.. And the result from Dr.Depth
And in 3D
I have put the Google-earth .KMZ files of the two lakes here:
That was all for this year so far..
Winter started early and all the lakes in the vicinity are frozen.
Much time for preparing new projects with ArduPilot...