GB2125261A

GB2125261A - Improvements relating to fish pens

Info

Publication number: GB2125261A
Application number: GB08217142A
Authority: GB
Inventors: Mark Arthur Perry; Brian O'hara; Robert H Williamson
Original assignee: BORSEA Ltd
Current assignee: BORSEA Ltd
Priority date: 1982-06-12
Filing date: 1982-06-12
Publication date: 1984-03-07

Abstract

A fish pen is constructed from a number of flotation units secured together end-to-end into a frame. Each unit is of box-section, with facing inner and outer channel members (1, 2) and sheets (4, Fig. 2) forming a deck and bottom, engaged inside the flanges of the channel members. Buoyant blocks provide an infill which is completed by foamed plastics material which expands to secure the components of the unit together and to distort at least the deck sheets into a slight camber. The units are interconnected by box-section bridging elements (10, Fig. 10) which plug into adjacent unit ends and are then bolted to the webs of the channel members. The pen is preferably of circular shape, and it will be equipped with stanchions and net supporting means. <IMAGE>

Description

SPECIFICATION Improvements relating to fish pens This invention relates to fish pens and is concerned with the type of pen described in our copending Application No. 8101431. This new version is of somewhat different construction and different shape and is expected to have certain advantages in strength and stability.

According to the present invention there is provided a fish pen comprising a buoyant frame with means for attaching a net to span the frame, the frame comprising radially inner and outer channel members with the channels mutually facing, substantially rigid sheet material engaging the insides of the channel flanges and spanning said members to form a box section, and an infill including foamed plastics material which expands before setting to secure said sheet material in place.

Conveniently, the infill may be blocks of polystyrene completed by foamed polyurethane which expands to fill all the interstices. The sheet material may be marine plywood. The upper sheets will form a deck, and as foaming proceeds the sheeting will be forced upwardly into an inverted curve, in cross section, thus providing a camber. The lower sheet will deform similarly. The channel members may be held in the correct relation by circumferentially spaced ties, preferably in the form of vertical stiffening plates welded to the insides of the channel. Sockets for stanchions may be welded to these webs, and the deck sheeting will have holes which register with them so that the stanchions can be dropped into place. There will also be various anchorage eyes secured at points around the outer channel member.

For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a fish pen, Figure 2 is a section on the line lI-Il of Figure 1, Figure 3 is a detailed plan view of the zone around the section line Il-li, Figure 4 is a section on the line lV-IV of Figure 1, Figure 5 is a detailed plan view of the zone around the section lV-lV, Figure 6 is a section on the line VI--VI of Figure 4, Figure 7 is a detailed plan view of a quarter joint, Figure 8 is a section on the line VIll-VIll of Figure 7, Figure 9 is a side elevation in the direction of the arrow A of Figure 7, Figure 10 is a section on the line X-X of Figure 7, Figure 11 is a side elevation of a stanchion, Figure 12 is a front elevation of a stanchion, Figure 13 is a section on the line XIlI-XlIl of Figure 12, and Figure 14 shows a handrail for fitting between stanchions.

The fish pen is an annular structure, designed to support a conical net which depends from it several metres into the water. The pen is constructed in four quarters, the joints in Figure 1 being at the cardinal point positions, and one of the joints being shown in more detail in Figure 7.

Each quarter comprises two curved channel members 1 and 2 centred on a common axis with their channels facing each other. Thus their flanges are horizontal and their webs vertical.

The channel members of each quarter are interconnected by two vertical stiffening plates 3 welded to the channel webs at a third of the circumferential distance from the ends. These plates have clearance with the channel member flanges to accommodate marine ply sheets 4 and 5 which form the deck and bottom respectively of the pen. A box section tube 6 is welded to one side of each plate 3 near the inner channel member 2, and this provides a socket to receive the base of a stanchion as shown in Figures 11 to 1 3. The deck sheets 4 have square holes cut in them to register with these sockets.

In each quarter, one of these stiffeners is further strengthened by a horizontal T-section bar 7 with plates 8 welded to its ends and to the insides of the channel section webs. A "U" bolt 9 is secured through this plate 8 to project from the outer channel member and provide an eye to which an anchor chain can be shackled.

The jointing of these quarters is shown in Figures 7 to 10. A rectangular box section member 10 with internal transverse stiffening plates 11 fits into the ends of adjacent quarters.

Externally, the webs of the channel members 1 and 2 are reinforced at their ends by plate 12, and drillings 13 are provided to receive bolts by which the assembly can be secured together. The member 10 leaves clearances between itself and the channel member flanges so that the sheets 4 and 5 can be fitted over and under it to form a continuous deck and bottom. A stanchion socket 14 has its base welded to the bottom of the member 10 and projects through the top, finishing slightly proud as best seen in Figure 10. An anchorage eye 1 5 is secured to the outer side of the box member 10 and this is accommodated in the small gap between the adjacent ends of the curved quarters.

For assembly, the four quarters are bolted together through the intermediary of the members 10 to form the skeleton of the pen. The bottom sheeting 5 is then laid in place, resting on the lower flanges of the channel members 1 and 2.

Blocks of polystyrene are then packed loosely into the annulus up to the level of the upper edges of the stiffening plates 3. It is possible then to apply foamable polyurethane and, before it expands and sets, quickly to slot in the deck sheeting 4. This can be done section by section. However, this is a tricky operation and it may be preferred to place the sheets 4 first and to have apertures through which the polyurethane can be injected, these holes subsequently being sealed off. In any event, as the foam expands, so it works its way between the polystyrene blocks and seals around them. It also exerts outward pressure on the sheets 4 and 5, and these will bow outwardly, being free to do so in the middle and being restrained at their edges which are forced firmly against the channel flanges and sealed to them. This gives the deck a desirable camber.

The stanchions 16 are inverted L-shape with a rib 17 welded near the bottom end to limit the entry into the sockets 6 and 14. Further up, on each side there are vertical tubular sockets 18 to receive the ends of guard rails 1 9 as shown in Figure 14. The horizontal arm will be arranged to extend inwardly of the pen, and on the end there is a horn formation on which to hook the nets. As well as the one for confining the fish, there will generaily be a cover net to keep off seabirds.

Claims

1. A fish pen comprising a bouyant frame with means for attaching a net to span the frame, the frame comprising a plurality of units interconnected end-to-end, each unit being of generally box section with bridging elements plugged into the ends of adjacent units to provide the interconnection.

2. A fish pen as claimed in claim 1, wherein the units are packed with blocks of bouyant material.

3. A fish pen as claimed in claim 1 or 2, wherein each unit has inner and outer channel members with the channels mutually facing, and substantially rigid sheets engaging the insides of the channel flanges and spanning said members to complete the box section.

4. A fish pen as claimed in claim 3, wherein the frame has an infill including foamed plastics material which expands before setting to secure said sheets in place.

5. A fish pen as claimed in claim 4, wherein the sheets are deformable by the foamed plastics material as it expands, thereby to adopt a camber.

6. A fish pen as claimed in claim 3, 4 or 5, wherein the channel members of each unit are interconnected by ties spaced circumferentially of the frame and secured to the insides of the channel webs.

7. A fish pen as claimed in claim 6, wherein stanchion sockets are secured to said ties and the sheets for the deck have registering apertures.

8. A fish pen as claimed in any one of claims 3 to 7, wherein the bridging elements are secured to the webs of the channel members and are covered by said sheets.

9. A fish pen as claimed in any preceding claim, wherein the bridging elements are box-section fabrications.

10. A fish pen as claimed in any preceding claim, wherein the frame is circular.

1 A fish pen substantially as hereinbefore described with reference to the accompanying drawings.