Claims:1. A trawling system comprising of plurality of trawl ropes (3 and 5) which connect a trawl net (12) to a trawler (1), wherein the plurality of trawl ropes (3 and 5) are provided with a plurality of visible markings (13) for identifying rope elongation.
2. The trawling system as claimed in Claim 1, wherein the markings (13) on the rope are provided at different spacing along the rope.
3. The trawling system as claimed in Claim 1, wherein the markings (13) are selected from any geometrical shape selected from rectangle, square, circular, conical and the like.
4. The trawling system as claimed in Claim 1, wherein the markings (13) are any kind of identification, discolour, stain, smear, coating, streaks, tracings, strips around and along the rope, label, band, watermark or stamps or combinations thereof.
5. A method for preventing skewing of trawl net comprising:
a. hauling a trawl net (12) on the trawler (1) during the catch when;
b. checking whether the trawl ropes (3 and 5) are of equal length by aligning the markings (13);
c. determining if the marking (13) align properly aligned, and
d. disposing of one of more trawl ropes if the markings do not align,
thereby preventing skewing of trawl net.
, Description:Field of Invention:
The invention relates to trawl ropes which connect the trawl net to the trawler. More specifically, the invention relates to a method of preventing skewing of the trawl net due to non-uniform length and loading of trawl ropes by providing special markings on the rope itself.

Background of Invention:
Fishing per se dates back to 2000 BCE in an Egyptian angling scene. As the world evolved, along with the population growth the demand for food kept on increasing.

Trawling is one of the methods of wild fishing. Currently trawling uses conventional ropes, either wire ropes or synthetic ropes. During trawling, due to environmental forces or due to rope elongation, the ropes may get loaded non-uniformly. This affects the trawl net orientation. The effect results in less fish catch. The operational costs and the profit are dependent on the fish catch per voyage. The uneven elongation of ropes leads to less catch and higher fuel consumption per kg of catch. Rising fuel prices have become serious problem to fleet owner.

Non-uniform length of bridle ropes deviate the orientation of the trawl net with respect to trawl direction and hence may affect the catch. Further, the bridles will witness non-uniform loads.

To get more catch, it is utmost important that the trawl net mouth opening should be high and the bridle ropes should be of uniform length. High forces from wind, wave and current acts on the trawl net and trawler itself create a dynamic force relationship between the two which lead to uneven elongation of the bridle ropes.

Despite significant advancement in the rope making technology, the operational benefits are not achieved. One way of determining the elongation is to mark the rope and align the markings. Few instances of such uses could be found in US4348907 (US ‘907), US7938468 (US ‘468) and US4992778 (US ‘778).

US ‘907 relates to a device cable reliability indicator. The device consists of a pair of monitor sleeves firmly attached at a preselected spacing on the mast raising line at a non-interfering position, and an associated measuring bar utilized therewith provides indication of the condition of the mast raising line upon each usage. In case of US ‘907, the elongation is determined by measuring the distance between sleeves. The sleeves are additional components which need to be manufactured separately, thereby increasing the cost of manufacturing.

US ‘468 discloses a method for determining elongation of rope using a set of markings, such as numbers which indicate excess elongation. Excessive elongation warning indicator means comprising a non-elongating body attached to said cover, wherein said non-elongating body is non-load bearing, and warning markings disposed on said cover, said non-elongating body further comprising demarcation means to indicate in combination with said warning markings the extent of elongation. Similar, to US ‘907, even US ‘468 requires and additional component which needs to be manufactured separately before it can be added to the rope for determining elongation. Hence the overall cost of manufacturing increases.

US ‘778 relates to a pre-failure tension warning arrangement for cables, webbing, chain, rope, wire, and cordage of all types and materials. The arrangement consists of an attachment to the cordage a visible element in an intact condition related to a first level of status of the cordage, said intact condition being caused by a bend in the cordage produced and maintained by the attachment of the element whereby said element imposes stress on the cordage. The estimation of the excessive stress in cordage is effected by breakage of the said visible element. Thus, even in case of US ‘778, the stress estimating element needs to be manufactured separately, and together with eventual loss of said visible element, tremendously increases the overall cost of manufacturing.

Over and above the prior arts as disclosed above, farmers in India use marking on the submersible ropes to measure the length of rope used to lower the pump, which is not related to the present invention.

Further, conventional trawl ropes do not have any design features which enable the user to identify the elongation of rope during the catch. Over a period of time, the ropes elongate non-uniformly and need repair or replacement. Since, the trawling is continuous operation and huge costs are involved, small deviation in alignment of trawl net may result in tremendous financial loss.

Hence, it is important to have a method which is economical and will enable workmen to identify the rope alignment and eliminate and/or minimize above-mentioned problems. Therefore, a method to prevent the skewing of trawl net due to non-uniform elongation and loading of trawl ropes during usage is needed.

Object of Invention:
Accordingly, it is an object of invention to provide trawl ropes which can be monitored for non-uniform elongation.

It is a further object of invention to provide a method of preventing skewing of the trawl net caused due to non-uniform elongation and loading of trawl ropes.

Summary of Invention:
In accordance with above objects, the invention provides trawl ropes which are provided with at least one marking on the rope to determine the rope elongation.

In another aspect, the invention provides a method for preventing skewing of the trawl net caused due to non-uniform length and loading of the trawl ropes by providing markings on the rope itself.

Brief Description of Drawings:
Figure 1 shows the perspective view of the trawling assembly and components thereof.

Figure 2 shows the trawl fishing net and the components of trawling in a view from top.

Figure 3 shows schematically the connection between trawl doors, the bridle rope and the winch rope.

Figure 4 shows the effect of uneven load distribution in the bridle ropes on the trawl net alignment.

Figure 5 shows the new bridle rope with markings used to identify the misalignment and to prevent disorientation of trawl net.

Detailed Description of Drawings:
Figure 1 shows the perspective view of the trawling assembly and Figure 2 shows the trawl net (12) viewed from top.

With reference to Figure 1 and Figure 2, the reference numeral (1) indicates a trawler which drags a trawl net (12) attached by warp lines (3) and bridles (5), through a winch (2). The trawl net (12) consists of a mouth (6), a belly portion (7) and a codend (8).

At the upper portion of the mouth (6), there is a headline rope (9) and plurality of headline floats (10) attached to the headline rope (9). Other components of the trawling assembly include trawl doors (4) and bridle ropes (5).

The winch (2) functions as the connection point between the trawler (1) and the trawl net (12). Warp lines (3), at their first end are connected to the winch (2) and at the other end are connected to trawl doors (4).

The trawl doors (4) act as a connection element for warp lines (3) and the bridle ropes (5). Connection between warp lines (3), trawl doors (4) and the bridle ropes (5) is schematically shown in Figure 3.

The trawl door (4) is connected, at one end to the warp line (3) and at the other end to the bridle ropes (5). The lower bridles (5) are equipped with a weight (11). This is to provide wide opening of mouth (6) and for stability of bridle rope (5).

When trawler (1) tows the net (12), there can be vibrations in the bridle ropes (5) due to sudden tension in the ropes. The weight (11) acts as a damper to reduce the rope vibration and hence increases the system stability. The headline floats (10) provide buoyancy to the headline and hence enhance the mouth opening during the trawling.

Now referring to Figures 4 and 5, Figure 4 illustrates the skew caused due to non-uniform elongation of one of the bridle ropes (5). This skew causes the trawl net (12) to be dragged at a skewed positon which might result in lower catch and/or excessive fuel consumption. To monitor this elongation of the bridle rope (5), the user needs to align the markings (13). This will enable the user to take corrective actions, if required.

Detailed Description of Invention:
Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the present teachings may be practiced. The following description is, therefore, merely exemplary.

Described herein is a trawl rope design. Specifically, the invention relates to design of trawl ropes, including, but not limited to, bridle rope (5) which is a connection between trawl doors (4) and the trawl net headline rope (9) and bottom line rope/chain, wherein these are submerged in water and continuously under the action of hydrodynamic forces during trawling and wherein the bridle ropes (5) are provided with markings (13).

For the purpose of this invention, the term “Marking” broadly applies to any kind of identification, discolour, stain, smear, coating, streaks, tracings, strips around and along the rope, label, band, watermark or stamps. The marking on the rope could be any one method mentioned above or combination thereof.

During the trawling operation various environmental loads acts on the net (12) as well as on the bridle ropes (5). The loads primarily include the drag load due to the current. Other secondary loads are due to trawler motion induced loads.

It is very important that the trawl net should follow the vessel course. Small deviation in the direction of trawl net will results in low fish catch and also cause large amount of drag, this adds to fuel costs.

During the catch the complete trawling system is immersed in the water. The trawler heads in the direction of fish spool. Hydrodynamic forces resulting from wave and current continuously act on the trawling system. Due to these forces and the drag on the net, the bridle ropes (5) may elongate. This elongation needs to be effectively monitored to prevent any undesired elongation of bridle rope (5) or any ropes involved in trawling operation.

Ropes with marking to identify the alignment have many advantages over conventional ropes. Therefore, rope elongation can be easily measured. After every haul rope length will be adjusted to keep the trawl orientation in the desired direction and hence to get higher catch and less fuel consumption..

A trawling system constitutes of many components as explained in the previous section. To get the desired results every component should work as per design.

In an embodiment, the invention provides a method for preventing skewing of the trawl net. Accordingly, during the catch when the trawl net (12) is hauled on the trawler, user can check whether the bridle ropes (5) are of equal length by aligning the markings (13). Checking the full length of bridles on trawls may not be possible due to space constraints. This will enable the user to take corrective actions, if required. This facilitates prevention of trawl net skewing due to non-uniform elongation of bridle ropes (5).

Accordingly, the method comprises of;
a. hauling a trawl net (12) on the trawler (1) during the catch when;
b. checking whether the trawl ropes (3 and 5) are of equal length by aligning the markings (13);
c. determining if the marking (13) align properly aligned, and
d. disposing of one of more trawl ropes if the markings do not align,
thereby preventing skewing of trawl net.
As the hydrodynamic forces may not be uniform, the bridle ropes (5) may elongate in uneven fashion. This uneven elongation of rope results in deviation of direction of trawl net with respect to the trawler (1) as shown in Figures 1 & 4.

The bridle ropes (5) are generally made of a polymer material. There can be more than two bridle ropes (5) on each side of the trawl net. This facilitates sharing the loads on the ropes. In accordance with one of the embodiments of the invention, the bridle ropes (5) are designed to have marking (13) on the rope at different locations along the rope, which can be visually seen. The marking can be circular, rectangular, square or any other regular or irregular shape.

In accordance with above embodiment, the bridle ropes (5) are made from polymer material. Polymer materials can be Polypropylene, Polyamide, Polyester, Polyethylene, HMPE, Aramid, LCP or combination of these.

It may be noted that, even tough, the embodiments of the invention relate to bridle rope these embodiments could be extended to any other trawl ropes involved in trawling operation. Such extension of the embodiments to other trawl ropes wold fall within the scope of the invention.

For the purpose of this invention use of plural terms for various elements of the invention does not preclude usage of the elements in singularity.

Example:
The example of the invention is as described with reference to the enclosed figures, where the bridle ropes are marked at certain interval, wherein the bridle rope is connected to the trawl mouth at one end and to the trawl door at the other end. The bridle rope which is used for trawl fishing is 16mm or thereabout in diameter. Breaking strength of the rope is approx. 4 ton. There are four bridle ropes in operation during fishing. Every rope has certain elongation behaviour in case of load application.
Assume that there are four bridle ropes are being used during trawl fishing operation. Bridle number 1&2 are on one side of trawl net and bridle number 3&4 are on the other side of trawl net. During the operation bridles 1,3&4 elongate more as compared to bridle 2 due to environmental forces. In this case the trawl net is skewed and fish catch will be less and higher fuel consumption per kg of catch.

To check the elongation, after every haul, all bridles are laid side-by-side on the deck of the trawler and measure the change in length is measured using marking on the rope and accordingly the rope length will be adjusted.