Project 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 controlled basis.
 
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 SECTION

 

Die MANTA mit ihrem damaligen Besitzer. Das Foto entstand ca. 2 Jahre vor ihrem Untergang.

 

The ROV with the installed gripper mechanism lying on the footbridge following a mission – and after successfully attaching the recovery cable.

 

An automatic snap-close mechanism is installed on the gripper arms for the remotely controlled positioning of the recovery cable.

 

The 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.

 

 
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