US2661562A

US2661562A - Trawling otter

Info

Publication number: US2661562A
Application number: US48252A
Authority: US
Inventors: Burney Charles Dennistoun
Original assignee: FRESH FROZEN FOODS Ltd
Current assignee: FRESH FROZEN FOODS Ltd
Priority date: 1947-09-18
Filing date: 1948-09-08
Publication date: 1953-12-08
Anticipated expiration: 1970-12-08

Description

C. D. BURNEY TRAWLING OTTER Dec. 8, 1953 2 Sheets-Sheet 1 Filed Sept. 8, 1948 Attorney Dec. 8. 1953 c. n. BURNEY 2,661,562

TRAWLING OTTER Filed Sept. 1948 2 Sheets-Sheet 2 F/GZ.

Attorney Federated ec. 8, 19 53 TRAWLING O'I TEB Charles bennis toun Burney, Londom England,"

assignor to Fresh Frozen Foods England Application September s, 1948', Serial No. 48,252

Ltd; London;

' Claims priority, application Great Britain September 18, 1947 The present invention relates to trawling otters, which are provided in connection with trawling gear for holding the mouth of the net spread open laterally against its naturaltendency to close up when being towed through the water. 3

Hitherto such otters have consisted of a flat wooden plane weighted along one edge (which, when in use, becomes the bottom edge) and which plane is adapted to be attached at points near its front and rear ends to the towing'wire and trawl net wire respectively. The points of attachment of the two wires are such that the otter assumes an inclined vertical position in relation to the direction of tow, so that as it is towed through the water the otter is forced outwardly and downwards whereby the side edge of the net to which the otter is attached is pulled outwardly from the axis of the net and the mouth of the net consequently spreads later ally.

The normal otter is non-buoyant and consequently rests on the sea bottom by its own weight in addition to the downward thrust given and the angle of inclination of the otter board. These two forces provide the-downward thrust necessary to take the net down to the bottom of the sea. As the otter travels along the sea bottom it is liable to catch in rocks and other obstructions on the sea bed, and therefore it requires to be very stoutly and heavily constructed to resist damage, and this in turn has the disadvantage of increasing the liability of the otter to bury itself on encountering an obstruction.

The main object of this invention is to provide an improved form of otter which will keep stable at all speeds in regard to its angular inclination to the axis of the trawl, independently of the pull of the towing wire and the drag of the net. Another object of the invention is to provide a simplified construction which eliminates the use of lateral planes on the vane memher.

The otter comprises a buoyant body streamline form and a vane member depending downwardly therefrom which is so constructed and mounted on said body that when the otter is immersed in water and towed, a water pressure on the vane results which causes the otter to 8 Claims.

travel outwardlyfrom'theline otitowfirThebte ter may therefore comprise a longitudinally attached vane member, preferably of aerofoil sec tion, which is disposed at'an inclination'to the longitudinal axis of the buoyant bodyand car: ries an attachment device for connection to a cable or wire whereby the otter is attached to the towing cable connected to'the 'netfi' According to the invention, in addition to be ing inclined to the longitudinal axis of the body; when in use the vane niem'beris' also inclined to the vertical plane so as "to produce a down ward thrust fromthe watches the" otter is towed along. This'downward thrust will eoun-' teract the buoyancy of the otter'and' tend to drive it down towards the sea bottom, thus preventing the otter from raising the net off the sea bottom by reason of its buoyancyfiTh'us whilst the natural tendency of theotter when at rest is to rise in the water (which owing to its lateral position in regard to the net it may safely do without risk o'f'foulingthe net) when the net is being towed, the otter is driven towards the sea bottom' and at"nor'm al" towing speed runs lightly over the sea bottom in such manner that it rides easily over any obstructions which are met. This vane member may be either fiat, or of curved shape, such for example, as of helical or helical cylindrical form, and the leading and bottom edg'eoi the vane may be reinforced by a strong metal bar which not only serves for protection but also as a weight to give the desired buoyancy to the ot'-' ter as a whole.

Preferably stabilising surfaces or members are provided at the tail end of the otter and these members may consist, for example, of radial vanes, to provide resistance to disturbance in the horizontal, vertical and other directions.

According to still another feature of the invention, in order to adapt the otter to work at widely varying sea depths, the float body is air filled and fitted with a non-return valve through which the body may be filled with air to any desired and suitable pressure. a In order that the invention may be clearly understood and readily carriedinto practice, it is illustrated, byway of example only, in the accompanying drawings, in which:

Figure 1 is a side elevation of one constru ctionoirotter accor ineitoit e..ini enii9n.-

Figure 2 is a plan view of the otter, and

Figure 3 is a front end View corresponding to Figures 1 and 2.

The otter comprises a buoyant body or float l which may be made solidly of buoyant material, or may consist of a metal shell filled with buoyant material, as cork or kapok, or simply made air-tight. Preferably, however, it consists of a metal shell or casing fitted with a non-return valve 2 so that air can be pumped therein to any desired pressure, adapted to assist in giving the necessary resistance to the shell to stand up to working at considerable depths of water.

The front end of the body i is rounded and it is encircled by

clamping bands

3, 3, 3, having lug portions between which is gripped with the aid of screw bolts 4, the edge of the vane member 5, consisting of a fiat or suitably curved metal sheet. The lower part of the leading edge of the vane 5 is rounded to facilitate its riding over obstructions, and the front leading edge, the rounded corner, and the bottom edge are reinforced by a strong metal bar 6 which not only gives the necessary weight to the otter as a whole,

but also protects the vane 5 from buckling or other damage.

As will be seen from Figures 2 and 3, the portion 6' of the bar 6 which supports the leading edge of the vane 5 is attached to the nose of said float, and is laterally ofiset a distance equal to the radius of the float body i so that the vane lies substantially along a datum line Y--Y. The vane 5 is curved in respect to said datum line YY which runs obliquely to the longitudinal axis of the float as, for example, at an angle 3 of from the periphery of its nose end to about its central axial point. The vane 5, as shown, is concave to the said datum line Y-Y.

The float is of streamline form, having a rounded nose, a cylindrical medial section, and a tapering conical tail portion. At the extreme end of the tail portion is mounted a stabilising ring I in advance of which are triangular fins 8 arranged radially in cruciform manner. These fins 8 and the ring I constitute a stabilising device against influences liable to disturb the course of the otter through the water.

A stay bar 9 is connected between one of the fins 8 and the rear corner at the bottom of the vane 5. the vane, 5, as best shown in Figures 1 and 3.

When in use the otter is connected by a wire or cable attached to the towing eye It? to a point on a branch towing wire or cable leading to the side edge of the net in advance of the net, and the pull of the towing wire or cable causes the otter, by reason of its inclined vane member to stream out sideways, thus exerting a lateral pull on the branch towing wire which is transferred to the trawl net and tends to open it laterally.

The otter when in use, assumes a position with the line X-X of Figure 3 vertical, so that the vane 5 assumes an inclined position whereby the water pressure on the vane surface 5 has not only a lateral component pressure on the otter outwards, but also a downward component counteracting the otters buoyancy, and calculated to prevent it from rising upwardly in the water and lifting the net off the sea bottom.

Owing to the buoyancy of the otter its normal tendency is to rise in the water when towing ceases, which is a point of considerable importance in preventing the otter from fouling the net when the trawling vessel stops, or slows down to change direction, whereas when correct tow- A towing eye l5 may be mounted on to 4 ing speed is reached a downward water pressure on the otter results which counteracts its buoyancy. Its action in this respect is quite contrary to that of a normal otter which sinks to the sea bottom when at rest.

It will also be appreciated that owing to its buoyancy the otter tends readily to ride over obstructions on the sea bottom and is thus little likely to suffer damage when in use.

I claim:

1. A trawling otter comprising a buoyant body of streamline form, and a vane member mounted on the body and depending therefrom, the vane member being inclined obliquely to the longitudinal axis of said body and including weight means whereby when the otter is immersed in water it assumes a position with said vane inclined to the vertical and horizontal planes, and a downward water thrust is produced thereby tending to drive the otter towards the sea bottom as it is towed through the water,

2. A trawling otter as set forth in claim 1, in cluding a stabilizing tail piece at the rear end of said body comprising a ring and a plurality of inner radial fins.

3. A trawling otter comprising a buoyant body of streamline form, and a vane member depending from said body and inclined obliquely to the longitudinal axis of said body, said vane member being mounted on said body eccentrically to the axis of said body so that the otter when immersed in water assumes a position with said vane inclined to the vertical and horizontal planes, whereby downward water thrust is produced thereon tending to drive the otter towards the sea bottom as it is towed through the water.

4. A trawling otter comprising a buoyant body of streamline form, and a vane member depending from said body and inclined obliquely to the longitudinal axis of said body, said vane being so mounted on the body that its centre of gravity is eccentric to the axis of said body, whereby when the otter is immersed in water it assumes a position with said vane inclined to the vertical and horizontal planes, whereby a downward Water thrust therein is produced tending to drive the otter towards the sea bottom as it is towed through the water.

5. A trawling otter comprising a buoyant body of streamline form, a vane member depending from said body and inclined obliquely to the longitudinal axis of said body, a towing connection on said vane member and weight and guard means on the leading and free longitudinal edges of said vane member, whereby the weight of the otter as a whole is so distributed that, when immersed in water, the movement of the otter by towing causes rotation of said body into a posi tion bringing the vane into an inclined position in relation to the horizontal and a downward water thrust is produced therein tending to drive the otter towards the sea bottom.

6. A trawling otter as set forth in claim 1, including a vane supporting bar portion attached to the nose end of said body, with a portion of said bar laterally offset by a distance equal to the radius of said body, said depending vane being attached at its leading edge to the offset portion of said bar, and support means connected between the rear edge of said vane member and said body and lying in a plane passing through the axis of said body.

7. A trawling otter as set forth in claim 5 wherein said support means comprises an inclined bar connecting the lower corner of the depending vane member at its trailing edge with the tail portion of said buoyant body.

8. A trawling otter as set forth in claim 1 wherein said vane member has leading and bottom edge portions curved in quadrant arc form, and said vane member weight means comprising a reinforcing and weighting bar mounted along said leading and bottom vane member edge portions.

CHARLES DENNISTOUN BURNEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Anderson June 14, 1921 Devoogt et a1 Apr. 4, 1925 Klaserner Nov. 9, 1926 Berger Jan. 29, 1946 FOREIGN PATENTS Country Date Great Britain A. D. 1908 France Oct. 20, 1923