GRALmarine, the company from Wrocław, for several years now has been manufacturing some of the world’s best lights in diving industry. I can safely say that you are now a leader, and your LED DUO lights are worth recommending.
How did you get the idea to involve in the construction of the remotely operated underwater vehicle (ROV)?
I have been interested in construction of ROVs for a couple of years. But previously, I perceived it primarily as a tool for inspection of underwater objects, supporting the diver’s work, underwater “tourism”, possible without entering the water.
At that time, divers established new depth records while diving in open water, expeditions discovered the wrecks of the Titanic and the Bismarck, others managed to reach the bottom of the Mariana Trench once again. Underwater vehicles, bathyscaphes, showed the ocean floor at a depth of almost 11 km!
However, on the mainland, in flooded caves, exploration results were less impressive in the range of 300-400 metres. Diving there posed great difficulties. Hard to reach, narrow cave corridors made it impossible to use specialist equipment. In many places even the transport of equipment was a big challenge for the diver.
Even the deepest dives ever performed were far from reaching maximum depth of flooded caves. Additional difficulty arises from the very profile of a given cave, which usually is not a vertical pit.
Watching graphic profiles of caves, you can almost always see in the bottom a horizontal line described with date, depth and name of the diver, who got there first. The drawing ends at the place when the measurement taken with a probe during diving, or by a ROV, stopped.
This is also the case for measurements of the Italian Pozzo Del Merro cave, the deepest one till this October. Underwater vehicles were brought there to the depth of 210 metres (ROV MERCURY), 310 metres (HYBAL 300) and 392 metres (PROMETEO). It is on the basis of that last measurement, that the Italian cave in 2002 was considered the deepest flooded one in the world.
When did you become interested in the Czech cave?
For many years, nothing changed. That is why it was hard to believe that less than three hours from Wrocław there is a cave, which may be the deepest cave in the world. This cave is Hranicka Propast near Ostrava.
Its initial underwater explorations date back to the 60s of the last century. In 1961, it was determined 6 metres deep. In subsequent years, measurements of divers and probes increased this depth to 373 metres.
First use of the electronic probe, certified by the Central Office of Measures, specially constructed by GRALmarine, stated the depth of 384 metres. The probe was descended by Krzysztof Starnawski from the depth of 200 metres. Diver’s bottom time, which was about 5 minutes, prevented the movement of the probe on a 200-metre long cord and further exploration of a deeper location.
Still, it was 8 metres less than in the Italian Del Pozzo Merro cave. As it turned out, the probe landed on the pile of scree stones, resulting from a landslide of a narrowing at the depth of 200-metres. Searching for greater depth in this manner could not be successful.
The only way was to explore the cave was using an underwater remote operated vehicle. The first attempt to explore the cave using the HYBAL ROV was carried out in 1995. Depth reached was 205 metres.
First step is always the hardest
Works on our vehicle started at the beginning of 2014. The first test for ROV GRALmarine would be to use it during an expedition in search of the ORP Kujawiak, sunk during the war, off the coast of Malta. We thought that depth in the exploration site will not exceed 120 metres.
In half a year, our vehicle was already tested and we took it on a trip. Even though it was damaged during the air transport, we were able to film the wreck at the depth of 95 metres. Such collected film material was the basis for the identification of the wreck by archaeologists from the University of Malta.
The depth was not too impressive, and moreover the vehicle was descended vertically, so in case of any malfunction we would be able to pull it out by the cord. Descending the ROV to the depth of 400-500 m was also possible.
The biggest problem was the cord, connecting the vehicle with the surface. It was 12 mm thick, reinforced with Kevlar, and it not only provided power from the surface, but also transmitted the video signal and control signals. It could work underwater for any time period. However, its length – 130 meters, along with a cable drum – barely met the weight limit permitted for air transport. The advantage was very high strength (over 1000 kg), the disadvantage was very high stiffness, making it difficult to enter corridors. It was equipped with one movable camera and lighting with adjustable power.
Vehicles conquering Pozzo Del Merro, Hranicka Proplast and other caves, were similarly equipped. As long as the cross section of the cave was vertical, with possible slight inclination, they coped with that. However, stiffness of the cord, along with its inertness, made it significantly more difficult to enter the corridors.
We decided to do it differently. We used optical fiber – cord with diameter of a match, flexible, durable, lightweight, and, importantly, retaining neutral buoyancy underwater. This allowed the vehicle to easily pull it from of the drum placed on the surface.
The only flaw of this method is lack of possibility to provide power from the surface. The vehicle is powered by internal lithium batteries, which allow it to work at full load for about 3 hours.
On the other hand, fiber bandwidth is a great advantage. You can easily transmit live image from multiple FULL HD cameras, placed on the ROV, compass readings, depth metre, computer, signals controlling the cameras, lighting and engines. This is not available with traditional cord. Flexibility and lightness of the optical fiber make it possible to go through horizontal corridors and narrowings.
The tests, in addition to the pressure tests held in the 600-metres chamber, were carried out in flooded quarries in “Podgórze” uranium mine in Kowary. We took this opportunity to make a recording from the depth of almost 180 metres, after reaching a collapse in the pit.
How were the beginnings of works with ROV in Hranicka Propast?
We have never been to Hranice before. We had no raw videos from the dives. We could only use films available in the internet to gain knowledge about the cave profile. Only two anchor lines were supposed to lead to the depth of 180 metres. We adapted our vehicle to such cave profile.
First time, we went to see Hranicka Propast in mid-September this year. We met the Czech ZO 7-02 Hranicky Kras crew on the site, and they really helped us in preparations before launching the ROV in the cave. We were impressed with how well they dealt with the transport of heavy equipment, including a bottle to be placed near the water. Great zip-line made of steel rope with a combustion winch. Height above the water surface is 74 metres.
Despite the beautiful surroundings and great weather, the trip was not successful for us. Main battery, powering the engines and lighting, did not work properly. We were forced to postpone the first test in water by one week.
Second attempt was not supposed to be the maximum submersion. First, we had to check how the block lays the optical fiber and dive to the bottom of the first pit, or maybe a little deeper. From the platform right above the water, the corridor is inclined at 45 degrees and after reaching 50 metres down, it turns into a vertical pit. This section of the corridor is narrow, the bottom is covered with sharp rocks, tree trunks and branches. To prevent blocking of the optical fiber in this section, it was led to the block, which greatly facilitated unwrapping.
At this first time, ROV was put in place by Krzysztof Starnawski. When he returned to the surface, we started descending the ROV. After 10 minutes, we reached the depth of almost 180 metres. That was the bottom of the first pit. It was covered with soft sludge, pieces of trunks, branches and leaves. We returned to the depth of 155 metres and went along the fixed rope towards the second pit. After several metres we started to lose it, covered with stones and leaves. We decided to go back to the surface. Krzysztof said that the next time he is going to install a new anchor line, in parallel to the old one. We returned to the surface easily.
We already know that on 27 September 2016 you managed to stir in the diving world, proving that Hranicka Propast is the deepest flooded cave in the world.
How do you feel now about that day?
When we arrived, Krzysztof Starnawski was already under the water, installing new fixed rope. Not waiting for him to return, we put ROV in the water and one of the divers led it to the depth of 50 metres and attached to the block. Meanwhile, Marcin Jamkowski was swimming around the vehicle, taking pictures and filming it.
We knew when Krzysztof will be back from decompression and we started to slowly descend into the new fixed roped. Although we moved slowly, passing by the old rope, we could not located the new one up to the depth of 180 metres.
In the meantime, after decompression, Krzysztof finished diving. Then it turned out that the new rope has been installed in other location, starting at the depth of 50 metres. Soon, we moved the ROV back to the surface in order to dive one more time, using the new fixed rope.
Depth metre showed digits associated with the records. On 200 metres we passed by the cord drum, with pressure transmitter installed at its end, indicating 384 metres. A moment later, ROV reached 205 metres, which is immersion depth of HYBAL ROV in 1995. We reached 300 metres, at 350 metres we saw the bottom, which was a little too quick and, above all, too shallow. Visibility got worse, but we saw darkness on the side. That was a good thing, at this point the cave should continue.
We went deeper… reached the probe depth – 384 metres – and moment later we were at 392 metres. We all held our breaths on the surface, as it was now clear that Hranicka Propast was at least as deep as Pozzo del Merro.
The bottom appeared on the camera, as we reached 400, 401, 402, 403, and finally 404 metres. We got to the bottom, proving that it is the deepest flooded cave in the world.
Above the water surface, we exploded with joy. Personally, I was only a little happy, as my success would be the moment for the ROV GRALmarine to reach the surface. In the front and rear camera we could see that the bottom goes even deeper. The temptation occurred: should we go on? However, the bottom was covered with trunks and branches in that section, so the vehicle might have easily got stuck. In addition, the depth was out of reach for any diver, which meant that nobody would be able to go 400 metres down to save the ROV. It was decided – we go back.
We reached 180 metres quite smoothly. Unfortunately at this depth, the vehicle got caught in anchor lines, fixed ropes etc. Additionally, a lot of sensor cables were placed there. They are danger to the ROV, as much as for a diver. The only difference is that underwater vehicle can wait on its own, no need to worry about the breathing gas.
Fortunately, this was a depth available for divers. We remotely disabled the vehicle. It had to wait, to be extracted…
Krzysztof Starnawski ensured that this will be done very quickly. The extraction was planned for two days later, but the Czechs were unavailable at that time, then heavy rain came, then Mountain Volunteer Rescue Service manoeuvres, then illness, then……, then…., and at the end of October, Krzysztof went to Mexico. I was emailed that the ROV can be extracted in March 2017.
A witness of such a momentous event is still waiting in Hranicka Propast, 180 metres below the surface, waiting for his saviour, that would extract it.
Without any doubt, Krzysztof Starnawski has done many great things in the field of exploration of flooded caves. Most of them, he managed to achieve by himself or with little help. However, we should remember that this record-breaking discovery in Czech cave was only possible thanks to the work of a number of people, who had been sacrificing their time and equipment for years, supporting the exploration of this place. Unfortunately, on the occasion of the nomination in the plebiscite of National Geographic Adventures of the Year, coming to end right now, we lacked reliable information on this topic.
Thank you for the interview. At the same time, I wish you many more successful endeavours at impressive depths!
In the material we used photos by Konrad Grynda.
You can read more about the ROV GRALmarine in the article ROV – hero of deep caves exploration (only in polish)