Patent Application
20100242336
1. Technical Field
The present disclosure relates to trawl nets, especially pelagic trawls and bottom trawls as used to catch fish including but not limited to fish known as cod, flounder, sole, haddock, rockfish, groundfish, flatfish, roundfish, blue whiting, mackerel, herring, capelin, Redfish, Alaska Pollock, other Pollock, Pearlside and other fish species. More particularly, the present disclosure relates to:
2. Background Art
T90 is a name applied to conventional machine made netting when turned 90 degrees (90°) in relation to the direction usually used in making a trawl. The concept of ‘turned mesh’ or T90 netting is not new. The use of T90 netting has been investigated since the late 1980s. Testing has demonstrated that T90 netting when used in certain ways possesses some advantageous properties over machine made netting used in the conventional way, usually identified as T0 netting. For example, laboratory tests indicate that T90 netting is stronger than T0 netting. T90 netting technology has been developed for whole trawl application by the Icelandic trawl manufacturer Fjardanet that is part of the Hampidjan group. When used in the codend of a trawl, T90 netting exhibits better catch quality, better selectivity and more efficiency than codends with netting turned in the conventional direction. Experiences using T90 netting in the bellies and codends of groundfish trawls targeting cod found T90 netting filtered out large proportions of undersize cod and the nets had the added benefit of being easier to tow. However trawls and especially their brailer bags formed of T90 netting have acquired a reputation for rupturing under operating conditions in which a brailer bag made of T0 netting does not rupture. Furthermore, trawls or portions of trawls such as codends or brailer bags formed from T90 netting have acquired a reputation for causing excessive gilling of fish, especially in the backend or “belly” of trawls, the “tube” that is forward of a codend or brailer bag, as well as the codend or brailer bag itself. These problems with T90 netting have occurred despite all the knowledge available in the industry. For the preceding reasons T90 netting has not been widely accepted in the industry.
There exist various ways of seaming together netting panels forming trawls, including different tapers, such as point and bar taper, all point taper, and the like. There are a plethora of factors involved in selecting how to seam one panel of netting to another in making a trawl. Furthermore, there exists no guarantee that one way of seaming panels together that is successful for one type of netting and trawl is going to be successful for another type of netting and trawl. That is to say, there is no assurance that a particular seaming, bating, taper, hang ratio, ribline non-use or ribline use with or without hangs or a succession of hang ratios and so forth that successfully functions for one type of netting in a particular portion of a trawl will also function successfully for another type of netting in that particular portion of a trawl, or that what functions well in one portion of a trawl will also function well in a different portion of a trawl.
Thus far, attempts to utilize T90 netting in the same way as T0 netting have failed, with excessive gilling of fish being the main problem, and tearing being another problem. As mentioned previously, despite being known for a long time that T90 netting exhibits advantageous properties, such as an the ability to increase water flow which is a long felt desire in the industry, due to T90 netting's unpredictability, large costs associated with a faulty product such as a trawl and/or codend, and losses in operational revenues from repeated failures of T90 netting to be used as is T0 netting, T90 netting has failed to become widely used in the industry, and has, in fact, earned a generally negative reputation.
“Panel” means a portion of netting formed of a plurality of meshes. Panels are used in a structure formed of netting, such as a codend. Panels of a distinct mesh type may include all or only a part of the netting that is between two or more selvedges, riblines or “corners” of a trawl. Panels are connected to one another along their fore and aft edges by seams. Synonyms for the word “panel” include “netting panel”, “portion of netting”, “piece of netting”, “section of netting”, and other.
“Seam” is used as both a noun and a verb. As a noun “seam” means the connection zone or portion of a trawl where any two or more portions and/or panels of netting are connected to one another, especially along forward and aft edges, and where each portion and/or panel of netting includes at least several full mesh cells. As a verb “seam” means to connect or join together a zone or portion of a trawl. Most commonly, two different panels of machine made netting are hand sewn to one another by hand weaving a series of half mesh used to connect the two or more portions and/or panels of netting. “Seam” shall not include the connection point of netting connected to headropes, footropes, sidelines, riblines or the like (netting connected to such lines, any lines and/or ropes not generally known in the industry as netting that is part of a seam), although where two or more portions and/or panels of netting are connected to one another, even if such lines and/or ropes are also connected to one or more of such portions and/or panels, that shall be known as a seam.
An object of the present disclosure is to provide an improved way for using T90 netting in a codend for a trawl.
Another object of the present disclosure is to provide a way for using T90 netting in a codend for a trawl that reduces gilling in comparison with former ways for using T90 netting in a trawl's codend.
Another object of the present disclosure is to provide a more reliable way for using T90 netting in a trawl's codend.
Another object of the present disclosure is to provide a way for using T90 netting in a belly, tube, brailer or codend of a trawl so that it is more reliable.
Briefly the present disclosure is a trawl system component and a method of producing a trawl system component selected from a group consisting of a trawl, a belly, an intermediate tube and a codend. The trawl system component includes T90 netting with at least a portion of the trawl system component including a first seam formed of a first panel of netting attached to a second panel of netting, the first seam having a seam ratio of less than one. At least a portion of the first panel of netting mainly is netting selected from a group consisting of.
i) T0 meshes; and
ii) T90 meshes having a mesh size of 160 mm or less.
At least a portion of the second panel of netting mainly is T90 netting having a mesh size of one hundred sixty mm or less. The netting forming the at least a portion of the second panel of netting has a lesser horizontal stretch measure value than the horizontal stretch measure value of netting forming the at least a portion of the first panel of netting. Within a trawl, the first panel of netting is situated forward of the first seam, and the second panel of netting is situated aft of the first seam. The trawl system component also includes at least a second seam located further aft in the at least a portion of the trawl system component from the location of the first seam. The second seam securing a third panel of netting into the trawl system component that is situated aft of the second seam with the third panel of netting being formed of T0 meshes.
These and other features, objects and advantages will be understood or apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiment as illustrated in the various drawing figures.
For the purpose of the present disclosure the terms “T90” and “T90 netting” shall include any netting:
In continued reference to
It is particularly important that the percentage of mesh opening provided by T90 mesh cells 1 be sized so as not to gill the target specie of fish, while also permitting escape of undersized and/or juveniles of such target specie especially in codends and tubes. Furthermore, it is particularly important to the best mode of the present disclosure that the diameter of a twine forming mesh legs 4 is at least 1.5% and preferably at least 2% of the mesh size of the mesh cell 1, also when measured “knot to knot” in the fashion described above. Presently, preferably the diameter of a twine forming mesh legs 4 is less than 3.5% of the mesh size of the mesh cell, with less than 3% being more preferred, with less than 2.5% being yet more preferred. However, experimentation can provide alternative ratios for the preceding parameters that are still useful though not disclosed herein, and such are intended to be encompassed within the scope of the teachings of the instant disclosure.
However, although in the instant example of
In continued reference to
The netting forming netting panel 24 preferably is T0 netting. The advantage of:
Netting panel 24 at seam 25 may have a lesser stretch measure value than does netting panel 23 at seam 25. However in order to most promote fish flow and quality of catch, in certain embodiments the stretch measure value of netting panel 24 at seam 25 is at least the same as, or is greater than the stretch measure value of netting panel 23 at seam 25, and may preferably be greater than is the stretch measure value of netting panel 21 at seam 22.
Where the illustration of
However, where the illustration of
It is to be understood that whatever construction of the present disclosure may be selected for use in forming the terminal end portion 36 that such construction shall include various elements not particularly pertinent to describing the novel aspects of the present disclosure and are thus not shown, such as but not limited to, knotting lines, lacing lines, hardware, chaffing gear and the like.
Thus,
Thus also,
In the instant example, the horizontal stretch measure value of the netting in panel 23 measured at both seams 22 and 25 is ⅔ (66.6%) of the horizontal stretch measure value of the nettings in panels 21 and 24, respectively. However, this ratio may vary as needed to obtain a similar length along a horizontal direction on a seam for a pulled taught portion of T90 netting when pulled taught horizontally from its intended orientation in the trawl compared to a pulled taught portion of T0 netting when pulled taught horizontally to its intended orientation in the trawl. This ratio when from 0.5 to 0.79 is presently preferred (i.e. the value obtained by dividing the stretch measure of the T90 netting portion by the stretch measure of the other netting portion, whether that other netting is T0 netting, T90 netting of mesh size lesser than 160 mm, or other netting, is the “seam ratio”). When the mesh size is 60 mm or less, a seam ratio of 0.66 (⅔) is presently preferred, with from 0.5 to 0.75 being presently useful, as experimentally determined. As the mesh size decreases and as the twine diameter increases relative to the mesh size, and thus the long dimension value 9 of the knot 2 increases relative to the mesh size, the seam ratio tends to increase.
Such a construction has also been shown surprisingly useful for codends where either (a) no riblines are used (i.e. the portion of the trawl having the seam lacks'riblines); (b) riblines are used that are not hung in shorter than 2% and that can be hung in as much as 10%; and (c) riblines are used where any hang on the ribline is the same or about the same on both sides of the seam.
The teachings of the present disclosure have been shown to be highly advantageous when combined with trawls having bellies and tubes having mesh sizes lesser than 160 mm.
When the T90 meshes are formed of mesh sizes lesser than 50 mm, it is also most advantageous that the seam ratio be less than 80%, with less than 70% being more preferred and with ⅔ (0.666) being yet more preferred. When the T90 meshes are formed of mesh sizes less than 40 mm, less than 35 mm, and less than 30 mm, the seam ratios are preferably 0.666 (⅔). When the T90 meshes are formed of mesh sizes of 20 mm or approximately 20 mm, seam ratios of ⅔ (0.666) again are preferred but with seam ratios from 0.5 to 0.666 being useful as experimentally determined.
When a portion of a trawl formed of T90 meshes is seamed to a portion of the trawl also formed of T90 meshes that have a mesh size greater than 60 mm, and especially greater than 80 mm, or that have a ratio of the diameter of the twine relative to the mesh size that is less than two percent (2%) or even less that two and a half percent (2.5%), and sometimes even less than three percent (3%) then sometimes the same seam ratio that applies for seaming T90 netting to T0 netting and that has been taught herein is also applicable, as should be experimentally verified.
In particular: a “knot value” is obtained by dividing the length 9 of the long dimension of knot 2 by the mesh size. When seaming together a first portion and/or panel of T90 netting to a second portion and/or panel of T90 netting, where the knot value is less than 22% and yet more critically when it is less than 20%, and yet even more critically when it is less than 15%, then such T90 netting may be considered as T0 netting for the purpose of the present disclosure, and especially when experiment determines that it should be so considered.
In other words, when a portion of a trawl formed of T90 meshes is seamed to a portion of the trawl formed of (a) T0 meshes; and (b) T90 meshes that have a knot value of less than 22%, then the seam ratio is less than one (1) and preferably is less than 0.9 (90%), and more preferably is 0.8 (80%) of less, and more preferably is lesser than 0.8 (80%), with from 0.5 to 0.7 being presently preferred, with 0.59 to 0.7 also being presently preferred, with 0.666 (⅔) presently considered most often useful.
The seam ratios of the instant disclosure as taught herein are especially useful when forming seams including T90 netting and T0 netting where the T90 netting has a “knot value” of at least 7%, and more preferably at least 10%, and yet more preferably at least 12%, and yet again more preferably of at least 15%, and even more preferably of at least 20%, and yet again more preferably of at least 25%, and yet even more preferably of at least 30%, and even more preferably in smaller mesh sizes such as lesser than 60 mm of at least 35%, with at least 20% being most useful for mesh sizes lesser than 80 mm, and with at least 22% being most useful for mesh sizes smaller than 60 mm, and more especially for mesh sizes smaller than 50 mm and smaller than 30 mm, and with a knot value of at least 25% being most useful for meshes lesser than 50 mm, and especially lesser than 40 mm, and most critically for meshes lesser than 30 mm and lesser than 25 mm. A knot value of at least 15%, at least 20%, at least 30% and at least 35% is highly useful for meshes lesser than 30 mm, less than 25 mm, than 22 mm and less than 21 mm especially when catching Pearlside fish.
Experimental verification is recommended to determine the best seam ratio in each case, whether when seaming T90 netting to T0 netting, or when seaming T90 netting to other T90 netting having a knot value of lesser than 25%, and yet more especially lesser than 22%, and even more critically of lesser than 20%, and for each particular construction of netting being manufactured, depending upon twine flexibility, elasticity, resistance to twine swelling and other, commencing, with the values taught herein. Such experimentation and the results and/or discoveries of such experimentation are intended to be encompassed within the teachings of the instant disclosure and contained within the scope of the present disclosure.
Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is purely illustrative and is not to be interpreted as limiting. Consequently, without departing from the spirit and scope of the disclosure, various alterations, modifications, and/or alternative applications will, no doubt, be suggested to those skilled in the art after having read the preceding disclosure. Accordingly, it is intended that the following claims be interpreted as encompassing all alterations, modifications, or alternative applications as fall within the true spirit and scope of the disclosure including equivalents thereof. In effecting the preceding intent, the following claims shall:
This patent application claims the benefit of U.S. Provisional Patent Application No. 61/211,521 filed on Mar. 31, 2009.
| Number | Date | Country | |
|---|---|---|---|
| 61211521 | Mar 2009 | US |
