Recovering Cargo or Submerged Objects Without the Aid of Divers.
The operating tube is here shown within the body of a hulk and
co-operating with the lifting derrick on the surface craft in the
removal of the submerged cargo. A grab-dredge bucket of well-known
construction is used, the jaws of which, when being lowered by one
rope, open, and when strain is brought on the lifting rope, the
jaws close. The working end of the tube is placed in the immediate
neighborhood of the cargo to be lifted and, as the grab is being
lowered from the boat above, the operator in the compartment controls
the grab by means of the guide line shown attached to the small derrick
boom, and leads it directly over the cargo to be lifted. The grab is
then dropped and the signal sent to the vessel above to hoist. The
moment the lifting line tautens the bucket grasps a load and fills
itself with material in the manner common to this type of dredge. This
method of directing intelligently and deliberately the dredge bucket
may be applied as well to the removal of rock or any other obstruction
or to any of those various services of kindred character familiar
to submarine engineers. The great and prime advantage of the system
is the fact that no divers are required, and the work is under the
perfect control of an operator subject only to atmospheric pressure. In
consequence, therefore, the only limit to the effective operating of
this apparatus is the length of the tube, and, as has been said, this
can be made long enough to reach depths denied to the diver simply by
interposing additional sections.
[Illustration: LIFE ABOARD A SUBMARINE