MANTA - Summary:
Following extensive optimizing
and extension work on our equipment, we set out on a search for the
sunken yacht of the "MANTA" type in July 2001. Our top priority in
the changes we had introduced to our gear was to retain the
reliability and the compact structure of all the components.
We had now fitted the ROV with two additional lights. These
additional light sources gave our camera a much broader scope for
its “filming range”. It could now be towed at a higher level above
the muddy depths of the lake and the great advantage of this was it
would make the search much more effective.
Furthermore the towed camera had now been improved by the addition
of a double-axis gripper, which was operated by the joystick on the
control panel which had also been re-designed and re-constructed.
The gripper now permitted us to both “hold tight” to any object we
were searching for, but more than this it now gave us the
possibility of attaching the recovery cable on a fully remote
The drive motors and the controls were modified so that the camera
could now perform self-propelled forwards/backwards movements. This
additional freedom of movement was not comparable with that of a
free-floating ROV. But what was now possible, was the capability of
approaching a found object over the last few meters independently
and under own power.
The search area was relatively small at 800x1200 feet, which meant
that a purely optical camera search was now altogether a feasible
option with a realistic prospect of success. The switched off
“selective availability” function in the GPS System permitted travel
on a very precise tracking course in the defined search grid.
We found the MANTA – the yacht we were looking for after only 6
search trips at a depth of 213 feet on 18 July 2001. Like the SALINA
we had already recovered, she was set on the mud bed of the lake in
a ghostly sailing position with her sails full set. On a third
encounter the cameraman steered our ROV under its own drive motor
power direct to the bows of the vessel. And he grabbed it here –
with the gripper installed on the towed camera – taking a hold on
the MANTA forwards at the pulpit in the bows. With the ROV cable
fully tensed we lowered an anchor into the mud bed directly adjacent
to the bows of the MANTA. A marker buoy was attached to this anchor
cable on the surface of the lake. This served on all the remaining
camera trips we made to the MANTA as a kind of lift or guide cable.
The ROV dived down to the MANTA time and again along this guide
cable and carried out further inspections. Some remarkable video
film footage was also made on these trips.
By using the gripper and a specially developed snap-close mechanism
– our snapper - we succeeded in a targeted anchoring of two recovery
cables in the rigging of the MANTA. On the 24 July 2001, less than
two weeks after the start of the search, we successfully recovered
the yacht from a depth of 213 feet. Once again we had no need to use
divers down at the vessel for the recovery.
END OF THE SUMMARY
Die MANTA mit
ihrem damaligen Besitzer. Das Foto entstand
ca. 2 Jahre vor ihrem
The ROV with the
installed gripper mechanism lying on the footbridge following a mission –
and after successfully attaching the recovery cable.
snap-close mechanism is installed on the gripper arms for the remotely
controlled positioning of the recovery cable.
recovery in the end-phase. The MANTA emerged ever more fully from the water
in an upright position at a quay.
A mere two hours
after the successful recovery the MANTA was thoroughly cleaned and moored
again at the quay.