Metal working – Method of mechanical manufacture – Disassembling
Patent
1998-07-23
2000-05-30
Bryant, David P.
Metal working
Method of mechanical manufacture
Disassembling
440 54, 440112, B23P 1900
Patent
active
060676973
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method as set forth in the preamble of claim 1 for removing a propeller assembly from and for mounting the same in an opening in the bottom of a swimming vessel as well as to an apparatus as set forth in the preamble of claim 4.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved and relatively simple and reliable method and apparatus for removing and mounting a propeller assembly for maintenance, repairs or replacement without having to bring the vessel to dock. This is particularly important in connection with various rig platforms used by off-shore industry, said rigs being often designed to remain stationary for long periods of time, e.g. up to 20 years. In the prior art, the propeller assemblies have been installed and removed from outside the vessel by means of various hoisting mechanisms. In a normal case, these necessitate the use of a diver for securing the hoisting cables to the propeller assembly. A drawback in such externally performed removal and installation of a propeller assembly is that such operations are highly dependent on weather conditions. In poor weather, a diver cannot be used for such operations for reasons of safety.
In order to achieve the above-described object of invention, a method of the invention is characterized by what is set forth in the characterizing clause of claim 1. On the other hand, an apparatus of the invention is characterized by what is set forth in the characterizing clause of claim 4 .
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described with reference made to the accompanying drawings, in which
FIGS. 1-3 depict one apparatus of the invention at various stages of removing a propeller assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1-3 illustrate an apparatus for removing a propeller assembly 1 from and for mounting the same in an opening 9 in a vessel bottom 8. The illustrated propeller assembly 1 comprises an underwater section 2, including the actual propeller, as well as a top section 3 inside the vessel, between which is a flange element 4 for tight sealing of the opening 9. The propeller is coupled through the intermediary of appropriate gear means to a gear shaft 5, which is in turn connected to power means 6, e.g. an electric motor or a diesel engine. In the depicted embodiment, the gear shaft 5 is removable. The opening 9 is associated with a hoisting chamber 7, extending upwards inside the vessel to above waterline and having its bottom portion provided with a passage 13 for the gear shaft 5. The hoisting chamber 7 is designed to be watertight.
Furthermore, inside the hoisting chamber 7 are included guide elements, not shown, for holding the propeller assembly 1 in a correct position during lifting and lowering.
The following describes the operations for removing and lifting the propeller assembly 1 from the opening 9. The description is but an example of one preferred implementation and is by no means intended to limit the scope of protection defined in the claims for the invention.
Firstly, the gear shaft 5 is disengaged from between the top section 3 of the propeller assembly 1 and the power unit 6, at the same time removing pertinent electrical wires and hydraulic tubes and other possible pipes. Next, the passage 13 is sealed with a watertight flange 11 (FIG. 2) and the top section 3 of the propeller assembly 1 is covered with a watertight protective casing 10. The next step is to unfasten the clamping elements which secure the propeller assembly to the hull of a vessel and to fasten hoisting cables 12 to the propeller assembly 1 and to let the water in the hoisting chamber 7. Finally, the propeller assembly 1 is lifted by way of the top of the hoisting chamber 7 and carried away for necessary procedures. Installation of the propeller assembly 1 into the opening 9 proceeds in a reversed order. The removal of water remaining in the hoisting chamber 7 during the course of installation can be effected by means
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Gale Chris
Savikurki Jarmo
Bryant David P.
Kamewa Finland Oy
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