Fishing – trapping – and vermin destroying – Fishing – Methods of fishing
Reexamination Certificate
1999-01-11
2002-04-23
Rowan, Kurt (Department: 3643)
Fishing, trapping, and vermin destroying
Fishing
Methods of fishing
C043S009100, C043S009800, C043S009950
Reexamination Certificate
active
06374531
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cell design used in a trawl system associated with capturing marine life within a body of water, and more particularly to an improved cell design (that by definition is iterated or cloned in varying geometric patterns) providing improved shaping and performance, especially when incorporated in midwater or bottom trawls of such systems.
In one aspect, the invention relates to mesh cell construction for trawls that can be triangular, rectangular and/or hexagonal in cross section (where such rectangular configurations include square cells) and is associated with at least three and preferably four cell (or more) bars in a common plane, with the length of each bar being measured between a pair of normalized transverse, quasi-transverse, longitudinal or quasi-longitudinal spaced-apart knots or equivalent couplers. In accordance with the invention, a pair of half mesh bars of each cell are constructed so as to fan out from a common knot or coupler (of the four knots or couplers associated with each quadratic mesh cell). Each mesh bar of such pair is constructed to provide hydrofoil-like characteristics in field operations. Each mesh bar comprises two (or three of more) strands each comprised of filamented synthetic material such as plastic or of a naturally occurring substance, each strand being the product of a conventional manufacturing process. In accordance with the invention, such the strands are constructed to be loosely twisted about a longitudinal axis of symmetry in a direction opposite (not the same) as its mating mesh bar. In addition, the pitch of the twist is controlled wherein each mesh bar defines a a range of pitch value, say from 3 d to 70 d and preferably 5 d to 40 d where d is the diameter of at least the smaller of the twisted strands. In another aspect, each mesh bar comprises a strap of synthetic or natural fibers of either rectangular, or quasi-rectangular cross section, preferably twisted along its longitudinal axis of symmetry whereby in operation the short sides form interchanging leading and trailing edges. In still another aspect, the invention relates to cell construction associated with tow, bridle and breast lines that attach to the trawl and improved performance thereof. Result: rather deep grooves are formed along the length of each cell bar that interact with passing water during operations as explained below. Note in this regard that the invention provides for a cell construction that can be systemized. In the case of a trawl, the opposite mesh bars of any rectangularly shaped mesh cell act as mini-hydrofoils or wings in concert in operations. Such opposite bars (whether formed of a series of twisted strands or of a single twisted strap), are characterized as having a common lay direction when viewed in an axially receding direction (either right-handed or left-handed lay) that is opposite to that associated with the remaining opposite mesh bars of such mesh cell.
When incorporated in a trawl system, such cell construction of the invention, provides for improved shaping and performance. That is, the cells positioned at different geometrical locations relative to and about the longitudinal central axis of the trawl, can be controlled such that resulting trawl panels, wings, bridle lines, towlines etc., act analogous to a series of mini-hydrofoils capable of acting in concert in operation. Such concerted action provides—when the trawl is in motion—outwardly directed force vectors which increase—significantly—trawl system performance characteristics including but not limited to overall trawl volume while simultaneously—and surprisingly—decreasing drag and background noise.
BACKGROUND OF THE INVENTION
It is well understood that the basic cell of a selected portion of every trawl system net is the unit cell (called cell hereinafter). The selected portions of the trawl system is then built by repeating the basic shape.
It is axiomatic that the ability to predict the overall shape and performance of the finished product depends entirely on the shape and structural integrity of that single cell. Heretofore, proper trawl making was a two-step process that involved initial construction of undersized mesh cells, and setting the knots and mesh sizes by the substeps of depth stretching and heat setting involving turning the finished mesh in direction opposite to its natural bent and applying pressure, and then applying heat to set the knots.
Materials used in the mesh cell construction can be plastics such nylon and polyethylene but other type of natural occurring fibers also can be (and have been) used. Single, double (or more) strands make up a thread or twine composed of, say, nylon, polyethylene and/or cotton. Additionally, braided cords, of natural and synthetic materials, as well as rope and cables, have been used. However, the pitch of any braided or twisted thread, twine, cord and/or rope (distance between corresponding points along one of the strands constituting one turn thereof) which is analogous to the pitch between corresponding screw threads), has been small. Moreover, modem manufacturing processes use threads. twines, cords, cables or ropes to form mesh cells, and have always produced cells in which twist direction of the individual bars comprising each cell, is always the same. None have proposed the use of differently oriented twist of individual mesh bars of the mesh cell in the manner provided by the instant invention.
Even though various Japanese Patent Applications superficially deal with nets having differing twist directions, (see for example, Jap. Pat. Apps. 57-13660, 60-39782 and 61-386), these deal with a contrary goal than that of the instant invention, viz., to a balancing of residual torque forces within the net structure during construction thereof, not to the generation of composite vector forces during actual field operations (via water flow-net shape interaction) for enhancement of net performance. The first-mention Application, for example, states that its purpose is to provide “net legs with different twist directions according to a fixed regular pattern so that torsion and torque of said net legs are mutually canceled” and must generate substantially inconclusive unbalanced forces during operations since the depicted net would lead to a shrinkage in net volume, not increasing net volume as provided by the instant invention.
SUMMARY OF THE INVENTION
The present invention is based on the discovery that individual bars of a cell can be controlled to act as mini-hydrofoils in operation. In one aspect, the invention controls twist direction, either right-handed or left-handed in a receding direction from a knot or equivalent coupler, in a fashion to provide for an improved shaping and performance of resulting trawl system.
In one aspect, the invention relates to mesh cell construction for trawls that can be triangular, rectangular and/or hexagonal in cross section (where such rectangular configurations include square cells) and is associated with at least three and preferably four cell (or more) bars in a common plane, with the length of each bar being measured between a pair of normalized transverse, quasi-transverse, longitudinal or quasi-longitudinal spaced-apart knots or equivalent couplers. In accordance with the invention, a pair of half mesh bars of each cell are constructed so as to fan out from a common knot or coupler (of the four knots or couplers associated with each quadratic mesh cell). Each mesh bar of such pair is constructed to provide hydrofoil-like characteristics in field operations. Each mesh bar comprises two (or three or more) strands comprised of filamented synthetic material such as plastic or naturally occurring substance, each strand being the product of a conventional manufacturing process. In accordance with the invention, such the strands are constructed to be rather loosely twisted about a longitudinal axis of symmetry in direction that is opposite (not the same) direction as its mating mesh bar. In addition, the pitch of the twist is control
Perevoshchikov Valentin G.
Safwat Sherif
OTTR Ultra-Low Drag, Ltd.
Rowan Kurt
Schreiber Esq. D. E.
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