Gilbert, after communicating to the surface ship that we had touched bottom,
started to head forward at full speed with the main propeller. The bottom was
abundantly sedimented and undisturbed. The objective was to reach the bottom of
the slope at 2450 m depth and then go westward to explore the base at contact with
the abyssal plain. We were going full speed (about 40 m per minute) and we were
in visual contact with the bottom. It seemed as if we were racing down the
continental slope. The gentle slope of about 6° was covered with sediment forming
parallel sedimented ridges about 2 m wide and less than 1 m high. These ridges
increased size down slope so in order to keep contact with the bottom the pilot had
to make a special effort. Suddenly, we felt a motion in the sphere: the keel of the
Archimède had touched one of the sedimented ridges. At that moment, we did not
know what was happening. It was only after continuing for more than two hundred
meters down slope, when the bathyscaph became completely immobilized, that we
realized what the problem was. In addition, there was no longer any visibility. We
saw only darkness through the porthole as well as on the back television camera
located on the tail of the submersible.
Harismendy communicated our position to the surface ship and said in a calm
voice that we were momentarily stuck at the bottom and that we could not move.
Both Jean and I were silent and we tried to keep busy by writing up our comments
of what we had seen through the porthole before we were stopped. Due to the fact
that we could not use our main engine and because the television camera on
the back was not sending any images, we came to the conclusion that the keel of
the bathyscaph was probably buried under sediment. We thought that when we hit
the slope, which we barely felt from inside the sphere, we must have triggered an
avalanche of sediment, much like turbidity current.
Gilbert did not want to release the ballast of the vessel, because this would
eventually make the submersible rise and that would be the end of our dive. So, at
first he started to use some of the other propellers in order to try to move the
submersible. In the mean time, we began to see the water and the sedimented
bottom in front of us because the suspended sediment was clearing off. We took
several pictures and continued to keep busy with our notes and by looking at the
radar screen and checking the video camera and our cassettes. Gilbert was still
busy trying out several ways to move the submersible. Then finally he decided to
empty the ballast. He pushed the electromagnetic release button, but nothing
happened. We had already been stuck for over an hour on the sea floor, and it
looked like we might be there even longer.
The three of us were sitting there, trying to make conversation. We waited a few
tens of very long minutes before we felt a slight motion. Archimède was rising up,
leaving the sea floor, and below the submarine we could now see the circular traces
of the iron pellets that had been dropped during Gilbert’s several attempts to empty
the vessel’s ballast on the sea floor. Then, to our relief, the submersible started to
rise irreversibly and we reached the surface at 14:28. It was certainly a nice feeling
to see the sun’s rays filtering through the water column near the surface. On the
basis of this dive, we all learned that submersibles should not explore by going
down slope but they should always travel up slope.
The FAMOUS project: The Mid-Atlantic Ridge near 37°N
179
started to head forward at full speed with the main propeller. The bottom was
abundantly sedimented and undisturbed. The objective was to reach the bottom of
the slope at 2450 m depth and then go westward to explore the base at contact with
the abyssal plain. We were going full speed (about 40 m per minute) and we were
in visual contact with the bottom. It seemed as if we were racing down the
continental slope. The gentle slope of about 6° was covered with sediment forming
parallel sedimented ridges about 2 m wide and less than 1 m high. These ridges
increased size down slope so in order to keep contact with the bottom the pilot had
to make a special effort. Suddenly, we felt a motion in the sphere: the keel of the
Archimède had touched one of the sedimented ridges. At that moment, we did not
know what was happening. It was only after continuing for more than two hundred
meters down slope, when the bathyscaph became completely immobilized, that we
realized what the problem was. In addition, there was no longer any visibility. We
saw only darkness through the porthole as well as on the back television camera
located on the tail of the submersible.
Harismendy communicated our position to the surface ship and said in a calm
voice that we were momentarily stuck at the bottom and that we could not move.
Both Jean and I were silent and we tried to keep busy by writing up our comments
of what we had seen through the porthole before we were stopped. Due to the fact
that we could not use our main engine and because the television camera on
the back was not sending any images, we came to the conclusion that the keel of
the bathyscaph was probably buried under sediment. We thought that when we hit
the slope, which we barely felt from inside the sphere, we must have triggered an
avalanche of sediment, much like turbidity current.
Gilbert did not want to release the ballast of the vessel, because this would
eventually make the submersible rise and that would be the end of our dive. So, at
first he started to use some of the other propellers in order to try to move the
submersible. In the mean time, we began to see the water and the sedimented
bottom in front of us because the suspended sediment was clearing off. We took
several pictures and continued to keep busy with our notes and by looking at the
radar screen and checking the video camera and our cassettes. Gilbert was still
busy trying out several ways to move the submersible. Then finally he decided to
empty the ballast. He pushed the electromagnetic release button, but nothing
happened. We had already been stuck for over an hour on the sea floor, and it
looked like we might be there even longer.
The three of us were sitting there, trying to make conversation. We waited a few
tens of very long minutes before we felt a slight motion. Archimède was rising up,
leaving the sea floor, and below the submarine we could now see the circular traces
of the iron pellets that had been dropped during Gilbert’s several attempts to empty
the vessel’s ballast on the sea floor. Then, to our relief, the submersible started to
rise irreversibly and we reached the surface at 14:28. It was certainly a nice feeling
to see the sun’s rays filtering through the water column near the surface. On the
basis of this dive, we all learned that submersibles should not explore by going
down slope but they should always travel up slope.
The FAMOUS project: The Mid-Atlantic Ridge near 37°N
179