The invention concerns a deflector to be installed in the tow-line between a towing vessel and a tow located in the water, e.g. a streamer, a cable with seismic sources or a seismic source array. The deflector is suspended on a float and is located between a tow point on the tow-line and an attachment point for further connection to the tow.
When an object or different types of equipment have to be towed through the water behind a vessel with the purpose of, e.g., performing special measurements, it is often important that the tow should not follow directly behind the towing vessel but should be pulled out to the side in order to follow a specific path. This is particularly vital in the case of seismic surveys, and at present this work is generally carried out with a number of tow-lines or chains of equipment which are towed in parallel paths behind a vessel. This may entail both individual groups of seismic energy sources for transmission of seismic pulses to the seabed, or rows of such groups of energy sources, or it may involve seismic streamers which are designed to record seismic reflection signals. In order to keep such tows apart from one another and at defined distances from the side of the towing vessel, a number of different devices have been developed. Float devices with rudders have been proposed which are attached to the tow-line at a suitable distance from the vessel, and a variety of otter board devices have also been used.
However, a common drawback for all of these designs has been some degree of sensitivity to sea motion, which has resulted in an erratic passage for the towed measuring equipment. This involves both the effects of wave movements on the otter board or float as well as various drift phenomena. For this reason continuous readjustments have been necessary, which have been difficult to perform, with the result that interruptions in the recording process have often had to be accepted and the tow path has not been exactly as planned.
There has therefore been an urgent need for a device of this kind, which can pull a tow out to a desired position or path behind a towing vessel and where this deflector is so designed as to "counteract" influences from its environment while at the same time adhering to a predetermined path.