Ships – Towing or pushing – Submerged object
Patent
1999-11-04
2000-11-07
Sotelo, Jesus D.
Ships
Towing or pushing
Submerged object
B63G 822
Patent
active
061420913
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a deflector for lateral spreading of equipment being towed in water by a vessel, such as during seismic exploration, fishing or mine sweeping.
Such devices of known design are substantially passive in their manner of operation, i.e. without any supplied driving power from an associated motor or the like. Typical examples of known designs are the so-called "trawl doors", being incorporated in trawling gear employed by fishing vessels. In mine sweeping there has been employed during long times for similar purposes, the so-called paravanes. At the outset the invention is directed to a deflector intended in particular for seismic exploration, but the deflector device may also be used in other applications, such as in fishing gear or mine sweeping equipment.
The invention is based on an effect known per se in the form of "lift", that occurs when a rotating cylinder is located in a flowing medium (Flettner rotor). By utilizing this effect there is according to the invention obtained an active deflector device for the above purpose, when employing motor power for rotation of one or more cylinders.
More particularly the deflector according to the invention is mainly characterized in that it comprises at least one cylinder adapted to have its axis oriented substantially vertically in the water during towing, that the cylinder or cylinders is/are rotatable and that there is provided at least one motor for rotating the cylinder or cylinders.
In practical embodiments of the device according to the invention it is preferred to employ more than one cylinder, preferably three rotating cylinders in each unit.
The deflector device according to the invention can give a very large effect in the form of a laterally directed force or lift for acting on the equipment being towed, at the same time as each unit has moderate dimensions and a very robust configuration with respect to a variety of stresses to which such equipment is subjected during transport, manupulation and towing in the sea.
Examplary embodiments of the device according to the invention shall be explained more closely in the following description with reference to the drawings, in which:
FIG. 1 schematically shows the towing of seismic equipment behind a vessel,
FIG. 2 shows an embodiment of the device according to the invention suspended from a float at the water surface, as seen in elevation and partial section,
FIG. 3 shows the device of FIG. 2 seen from below and with a motor removed, and
FIG. 4 shows another, preferred embodiment of the device according to the invention, in a somewhat simplified manner and in perspective view.
FIG. 1 shows a seismic vessel 1 which via a number of cables or towing wires 2 tows a number of hydrophone cables or streamers 3, whereby the towed equipment also can comprise seismic gun groups. In the example shown eight streamers 3 are incorporated, and these have been pulled out laterally to either side in relation to the centerline of the vessel 1, so that there is established a desired, wide range of coverage during towing of this equipment. For such lateral pulling-out of a towed seismic arrangement to a large width, there are previously known various forms of deflector devices. The particular deflector to be described here, is represented in FIG. 1 by two units, namely a deflector 5 at one side and another deflector 7 at the other side of the towed arrangement, i.e. at the leading end of the seismic streamers 3.
As indicated in particular for deflector device 5, this comprises three cylinders 5A, 5B and 5C being adapted to stand upright approximately vertically in the water during towing, and the device 5 is connected to an outer, port towing wire or cable 2A through a cable piece 6, that may constitute a direct prolongation of the cable 2A. A so-called straddle 6A is arranged between the outer end of cable piece 6 and the actual deflector device or unit 5. In this example cable 2A is provided mainly for towing the deflector 5, but in other embodiments this can be towed without using any separate cabl
REFERENCES:
patent: 3404655 (1968-10-01), Fohl
patent: 3797444 (1974-03-01), Stubbs
Evjen Kristian
Henriksen Ove
Pratt Dave
Sotelo Jesus D.
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