Pair_Trawl_Specifications_143041240070.pdf

Pair Trawl Specifications for Solicitation

Interested Venders:

Listed first are some general comments on the trawl specifications, materials, and design considerations Specific drawings and additional details are on following pages.

We have utilized large surface pair trawls specialized for sampling juvenile salmonids containing passive integrated transponder (PIT) tags in the Columbia River since 1995. The original trawl design consists of variable mesh wings, a floored section with head rope and foot robe, and a trawl body leading to an antenna attachment. The design has been modified through the years primarily due to antenna design and electronics improvements. Due to the requirement for long and consistent sample effort, in often difficult and high debris load conditions, backup trawls are required to maintain the sample effort.

Currently, we have a backup trawl constructed in 2009 and a primary trawl with slightly modified design and construction materials built in 2012. This 2013 trawl would be a 2nd primary trawl as specified herein. Our older 2007 trawl constructed 2007 and extensively repaired recent years, will be retired for parts.

Though the descriptions and materials for our specialized trawl are specified below and major changes are not anticipated, vendors may suggest modifications and substitutions which might be allowed with advanced approval. PIT tag detection technology now allows for larger antenna designs than used previous and the trawl body attachment must match the antenna size. The 11/16 stretch measure #210\15 or #210\18 measure knotted web specification described below is critical to the design by its demonstrated use with small sized migrant salmonids. After testing in 2012, we preferred the slightly heavier #210\18 but will accept substitution of #210\15 if necessary. Slightly larger mesh size (3/4 inch mesh) has major fish gilling problems and causes high mortality with sub yearling Chinook salmon.

Slightly smaller mesh creates unnecessary drag. We have used knotless 11/16 inch in older trawls but prefer knotted 11/16 inch mesh now due to better strength and less drag. We can allow no substitution for the basic 11/16 inch mesh specifications and are reticent to allow substitution for other components due to concerns about comparing sampling efficiency between a new trawl and existing trawls.

The trawl body (portion of trawl downstream from the head and rope rope) is asymmetric in design as the antenna attachment is closer to the surface than to the bottom of the trawl resulting in top, bottom, and side panels of the trawl body web cut with different tappers. In 2010, we experimented with and settled on a 100 foot trawl body length as specified here. The 2009 trawl was retrofitted with the longer trawl body and subsequent trawl bodies are of this design. The increased trawl body length and change in webbing from knotless to knotted improved the float to sink ratio and returned the cork line to the surface using our larger and heavier antennas. There is a delicate balance between drag and adequate floatation needed to keep the cork line on the surface. Net reel capacity on the boat also limits the quantity of bulky corks possible for floatation and must be matched by the depressive force of the lead line needed to provide desired sample depth. Too little lead and sample depth is lost. Too much lead sinks and the cork line pulls under, allowing fish to escape over the top. Modifications to cork and lead line specifications will not be accepted.

Additional specifications and descriptions follow. A schematic drawing (not to scale) is shown for the overall trawl and specific details for various components are found on subsequent pages. Suggested for improvement on this experimental net are welcome but we can accept no variance to the specifications without prior approval due to the specialized nature of the scientific equipment used for sampling.

40 ft spectra

(1.5 in mesh, #15 web)

(11/16 in mesh knotted web, #210\18 or 15)(1 in mesh, #12 web)

100 ft (240, 4 oz. leads, 60 lbs. total) 100 ft

Floor, 30 ft on center (34 ft. stretch), see detail

(Leadline, 1/2 in diameter Amstell (spectra) with ring-leads added)

Corkline3 , 5/8 in diameter Tenex and Amstel (spectra)

99.5 ft

Trawlbody

(11/16 in kk mesh #210/18 or 15)

Spreader bar 10 ft

Bridle

Towline

W i n g

Trawl (English units, 27 Oct 12)

Terminus: Web cut to match the opening of the

Matrix Antenna (8.5 ft wide by 10 ft deep, centered at 7 ft below surface). Bolt rope used to terminate the end.

240 ft

300 ft

100 ft (432, 4 oz. leads,108 lbs)1

60 ft tenex 100 ft tenex

100 ft tenex (25, 3.5 lb/cork on 48 in centers)

(77, 3.5 lb/cork on 16 in centers)

(46, 3.5 lb/cork on 8 in centers distal 31 ft and 52, 10lb/cork on 16” centers, 68 ft)

Perimeter line2 Floor leadline, 404, 4.0 oz leads, total 101 lbs

Head rope (15/40/15, 3.5 lb/cork on 8 in centers, 245 lbs.)

Breast line2, 15 ft (2)

1. Floored-wing section leadline: distal 88’ with 384, 4 oz. leads (-96 lbs.) and final 12’ with 48, 4 oz. leads (-12 lbs.).

2. Perimeter line, a double 7/16” diameter Tenex (or equivalent) line running across top and bottom web panels but with sides laced mesh to mesh. This line separates the trawl body (rear) and floored-winged section (forward). Web from each component is hung to these lines allowing for easy separation (replacement). Breast lines of same 7/16” diameter line at ends of each wing section and laced mesh to mesh.

3. Corks with grommets, 2-styes: Smaller 3.5 lb. floats BL-6, BAO long (or equivalent) and larger 10 lb. floats (BL-10, BOA long (or equivalent).

4. Distal and middle wing cork lines and all lead lines hung using mesh and a half (#84, 2.5” X 1.5” deep knotted black nylon) technique to union smaller mesh to main strain lines. Web for proximal wing cork line (11.16” mesh) is hung first to 7/16” bolt rope, which in turn is hung to cork line. All hangings #36 twine secured with ‘knot seize’.

Breast line2, 20 ft (2)

(240 4 oz. leads, 60 lbs.

total)

Winged-floor section (rectangle) Middle wing section (taper)

Distal wing section (taper)

Not to scaleBreast line2, 10 ft (1)11ft 12ft

Juvenile salmon surface pair trawl. As built by vendor and delivered 12 June 12.

The revisions here reflect that design and some minor changes

Floored-wing section of trawl. The floored body wing-section is constructed entirely of 11/16 inch knotted mesh (#210/18 D, #6 strand preferred but #210/15D #5 strand acceptable). This is the same 11/16” knotted webbing used in the trawl body section. Foreign manufactures known to require a minimum 3 month delivery schedule. As delivered, the 2012 floor measures forward of the perimeter line 30 ft.

on center (34 ft, stretch measure). The leading edge of the floor joins the wings about 62 ft. forward of the perimeter line on each side. We requested that the corks for this body wing be attached to the 5/8” dia. main Tennix line using a 1.2” Tenex ‘sister’ line with treaded corks to ease replacement). See additional figures for specific construction details of the trawl body and the distal and middle wing sections. Those components are shown here only for perspective of the whole trawl.

Cork and Lead counts: Floored-wing section (11\16” mesh)

Body Wing Corks: On 5/8” Tenex Corkline 100 ft. length: Perimeter line to 69 ft. forward: 53, BL10 (10 lb corks) BAO long on 16” centers, +530 lbs., distal 31 ft. 52, BL6 (3.5 lb.) BAO long on 8” centers +182 lbs., total +712 lbs.

floatation on each wing.

Body Wing Leads: On ½” diameter Amstell (spectra) line 100 ft. length:

Perimeter forward 88 ft. 384, 4 oz. leads (-96 lbs.) and remaining 12 ft., 48, 4

oz. leads (-12 lbs.), total -108 lbs. depressive force (lead) against corks each wing.

Head rope and triangular reinforcement at corners: 30 ft. between the wings (20 ft. in center with corks), and 13 ft. triangles of web reinforcement (over corners): 70, white BL6 (3.5 lb.) corks, BAO long on 6 in. centers (+245 lbs. floatation). Note that there are no corks on the 10 ft. of perimeter to rearward of the head rope triangles.

Foot rope (30 ft. between the wings and is part of the ‘perimeter line’ separating the floored section of the trawl from the trawl body ): On ½” dia.

Amstell (spectra) line, 117, 4 oz. leads (29 lbs.).

Floor lead line (30 ft. on center forward of footrope): Amstell (spectra) lead line forms the leading edge of the floor (sample depth) and is 103 ft. 4 in. total length. Where it joins the wings on each side is 62 ft. forward of foot rope perimeter line. Total lead: 404, 4 oz. leads = -101 lbs.

Total floatation (corks): (712*2 wings)+(245 head rope) = 1,675 lbs.

Total depressive force (lead): (113*2 wings) + (101 floor) + (29 footrope) = 356 lbs.

Ratio float to weight = 5 to 1. This seems out of balance but the 2012 trawl, while on surface, did not seem excessively buoyant. More tests of sample depth at center of floor needed by temporarily adding weight at corners of perimeter line to achieve maximum sample depth with corks remaining on surface.

Tapper cuts floor: Hang all web edges (11/16” webbing) to 7/16” Tenex line. Floor mesh is square cut along rear 30 ft. of perimeter line, It is also square cut 30 ft.

forward of the perimeter line for a span 20 ft. wide on center. Along each wing, beginning at perimeter line, floor mesh is taper-cut forward 1 bar and 2 points going forward. The leading edge of the floor, 30 ft. forward of the perimeter line, is tapper cut on each side of the middle square cut section, at 2 bars 1 point for 9 ft. 8 in. then forward again along each side the remaining 32 ft. (reaching the splice into each wing) using straight bar cuts. The splice where the wing lead line and floor lead line join is about 62 ft. forward of the perimeter line along the wing.

Mesh-and-a-half (M&H) technique: To ease tearing caused by hanging smaller mesh to cork and leads lines, we recommend using a strip of #84 black 2.5” stretch measure by 1.5 “ deep braided knotted nylon between, dyed black and tarred. This M&H strip is hung directly to the main strain lines (cork and lead lines) and the smaller lighter mesh hung to that (color-coded hangings preferred). The exception is for the 11\16” web mesh in the cork line for the body wing closest to the entrance to the trawl body where no M&H is used. That section of mesh to be hung to a 7\16” bolt rope instead, which in turn is hung to the cork line (this to prevent potential gilling fish in the M&H as they approach the head rope and entrance to the trawl body.

Trawl Wings as built 2012

Tapered 100 ft lengths of 1.5-in stretch measure and 1.0-in stretch measure knotted mesh

Corklines, 5/8 in diameter Amstell (spectra), for shock load resistance, and Tennix as shown on distal wing, and entirely 5/8” Tennix on middle wing section. Cork with grommets (3.5 lb. floats, BL-6 or equivalent) are threaded individually onto the cork line at spacing shown. Cork counts: 1.5” 25 BL6, BAO long (+88 lbs.); 1.0” 77 BL6, BAO long (+270 lbs.).

Strain lines terminate with “soft-eyes” for joining to adjacent components.

Leadlines of all wing sections use ½-in. diameter Amstell (spectra) line. Individual seine-type leads are treaded over the lead line at the densities shown on the drawing. Lead counts: 1.5” 240, 4.2 oz. (-63 lbs.); 1.0” 240. 4.2 oz. (-63 lbs.).

The taper cut mesh of each wing is terminated top and bottom by lacing the small mesh to M&H and hanging the M&H to cork and lead lines in the usual fashion. Mesh along the vertical terminations are directly hung (#18 black or dark) to 7/16” Tenex breastlines. Adjacent wing breastlines are laced together (#36 white) and lashings used to secure the cork and leadline soft-eyes.

Knot-seize or equivalent used to secure all hangings. Hangings use #18 black or dark nylon twine.

100 ft

15 ft 10 ft

20 ft 15 ft

Distal wing section 1.5-in. knotted #15 mesh (taper cut)

Middle wing section 1.0-in. #12 mesh (taper cut)

40 ft 5/8”spectra 60 ft 5/8”Tennix

(25, 3.5 lb./cork on 48 in centers) (240, 4 oz. leads, 60 lbs. total)

(77, 3.5 lb/cork on 16 in. centers) (240, 4oz leads, 60 lbs total)

Breast line (7/16” diameter ), terminate end of each wing section and laced mesh to mesh

= Mesh-and-a-half (M&H) transition using #84 black 2.5” stretch by 1.5” deep braided knotted nylon

Trawl body specification revised as built for 2012 trawl body. This 100 ft. long (on center) trawl component is entirely behind the head and foot ropes and has no lead lines or cork lines. It is an asymmetrical design thus with side panels cut different from top and bottom panels. There are 6 longitudinal rib lines to better support tow of antenna and includes 8 heavy duty industrial zippers (8, 12 ft-long zippers total) staggered along left and right sides of the top center rip line with about 2 ft. between zippers. Zippers close downstream towards the antenna.

Trawl body assembly. The 2012 new trawl as built appears to have substantially more web per foot than previous trawl bodies. We will decrease the webbing by about 5% on that design as described below. Constructed of 11/16” knotted webbing (210/18D, #6 strand). [Divide the 15D (alternative web) or 18D by 3 to get the strand size, thus this is 6 strand web]. Overall the entrance to the trawl body measures 29.5 ft wide (roughly 30 ft. at head rope and foot rope) by 20 foot deep (sides) opening. The trawl body sections then taper smoothly back 100 ft. along corner rib-lines that help secure the antenna to the trawl (see below). Rib-lines of the trawl body section is the same 7/16-inch line as used with the perimeter lines.

Construction specifics: A manufactured ‘bail’ of 11/16” knot to knot stretch-measure web material counts 400 meshes wide by 11,000 meshes long. At

400 meshes, the total horizontal ‘stretched-length’ of a trawl body cross panel is about 20 feet long (0.6875 in. ms-1). As measured in direction of fish movement, 5 such stretch panels provide a total trawl body potential length in excess of the needed top center length of 100 ft. To obtain a relaxed open mesh lay, a 0.624 in. ms-1 is required, providing a 104’ total length (2002 meshes) potential in 5, relax-lay 20.8 ft long panels. Any slight variation in the working length and width is spread evenly thorough a running dimension.

Panels are joined on corner rib lines but we request additional top and bottom center rib lines be added to better secure trawl to antenna. Web panels are tapper cut and hung to the side rib lines. The top and bottom center rib lines are added through the web for added strength of antenna attachment.

Originally, vender hung 2002 meshes along the 100 ft. rib line in 5, 20 ft. long panels (running around the trawl body). The 2012 trawl body appears to have excessive webbing hung in these panels and we wish to reduce by 5% in this design. At the perimeter lines, the panels were 608 meshes deep on sides (20 Ft. depth) and 5% less would be 578 meshes. The top 30 ft. wide panel began at 950 meshes and would reduce to about 902 meshes. Similarly, the bottom panel reduces from 950 to 902 meshes. Tappers cut along the 5 mesh panels towards the antenna should reduce smoothly with no pockets.

Tapper cuts: The cut web sections of the trawl body are ‘hung-in’ along longitudinal rib-lines on top and bottom corners using a relaxed hang at about 90%, (about 20.8 feet longitudinal feet per 400 mesh panel). A rib-line is used at each of the four side panel seams and top and bottom center rib lines added for support (6 total). The taper from the top rear of each side panel for this trawl body length is 31 points and two bars (in) bringing the tail end down 18 inches. The corresponding taper from the bottom rear of each side panel for this length is 9 points and two bars (in) to bring the bottom up 8.5 feet. This asymmetric tapper leaves a vertical opening of 10 feet at the tail of the trawl to match the antenna opening. The top and bottom panels are tapered 6 points 2 bars (in) on each side (10 feet removed from top and bottom panels equally) to bring the tail to a horizontal opening of 8.5 feet. All tapers are cut with a hot knife to prevent the mesh from fraying. The four panels are then sewn together with #18 black nylon (or equivalent) twine, the completed body is then terminated with 7/16-inch diameter black-colored line to hold shape when under tow. This black line is sewn into the web at the terminus of the trawl body as a ‘bolt-rope’, for later addition of 1.5” diameter plastic rings on 13” centers. The rings align with similar rings on the antenna and a serpentine line is used between the rings on each side enabling fast attachment/removal of antenna components when changing trawls. The 6 longitudinal rib-lines along the trawl body extend towards the antenna an extra 3-ft beyond the web and bolt rope for attachment to the antenna and take the load of the antenna under tow on the rib lines rather than through the webbing.

Perimeter lines: A perimeter line typically terminate the trawl body web panels where it joins the head and foot ropes of the floor section of the trawl (no corks or lead on the trawl body side). We have recently (2010) eliminated the side perimeter lines on the vertical seam between trawl body and floored section of trawl and instead lace mesh to mesh the two sections of 11/16” mesh together along the sides using #18 twine.

Floor of 2012 trawl ‘as-built’, top view. Note the drawing is not to scale and should be symmetrical to the center. At full spread, when attached to wings 62 ft. forward of perimeter line, the floor should have about 86 ft. spread between the wings. The total length of the lead line along

Leading edge of the floor is about: 103 ft. 4 in.

(20.0+9.7+32.0+9.7+32.0) ft. not counting splices. Tapper cuts shown. 10 Jul 12.

Perimeter line\ footrope and lead line

Wing

100 ft.

11/16”

Web

(#210/15 or #210/18)

62 ft.

38 ft.

Floor 11/16 web

Width @ perimeter is 30 ft.

1,150 meshes)

20 ft.

(604 +/- meshes

Square cut)

700 meshes (30 ft.) from the leading edge of floor to entrance of trawl body

(34 ft. stretch measure)

32.0 ft.

2 bars :

1 point

Straight bar

1 bar 2 points

As-built 2012 Trawl floor ( t 12)

Full spread 120 ft @ 100 ft forward of perimeter line

Total width of floor at full spread (estimate) = 86 ft. +/-

10 Jul 12. Note also that the stick drawing ‘odd’ corner tapper as drawn is backwards. The tapper counts are correct, but where the 2 bars and 1 pt.

tapper transitions to straight bar, that angle should appear opposite of what is drawn.

9.7 ft.

16 Oct 12.

Floor detail of 2012 trawl ‘as built’, top view. Note the drawing is not to scale but is symmetrical to the center. At full spread, when attached to wings 62 ft. forward of perimeter line, the floor should have about 86 ft. spread between the wings (an estimate based on geometry). The #210/18, 11/16” knotted web of the floor is square cut 700 meshes forward of the footrope at the entrance to the trawl body (footrope) for a 20 ft. width. The tapper cuts (2 bars\1 point as labeled) proceed forward 9.7 ft. on each side, then change to straight bar cuts another 32 ft. and joint the lead line of the wings. The total length of the lead line along leading edge of the floor is about 103 ft. (20.0 center+9.7+32.0 +9.7+32.0 = 103.4 ft.). The rear of the floor is square cut 30 ft. wide and proceeds forward 62 ft. along each wing using a 1 bar/2 points tapper cut. The web is hung to a 7/16” Tenex line (black preferred) with #18 braided twine (white or green preferred). The 7/16” Tenex line in turn is hung to the main ½” Amsteel (spectra) or equivalent lead lines. The lead line along the leading edge of the floor is 103.4 ft. long and fitted with 4 oz. seine leads on 3” centers (404 total or 106 lbs). Note. If #210/18 web is not available for the floor, slightly lighter weight #210/15 ,11/16” knotted web may be substituted. The estimated the spread of the wings, 62 ft. forward of the perimeter line where the floor attaches, is about 86 ft.

Mesh counts: There are 700 meshes on center across the body of the floor from the perimeter line forward 30 ft. (34 ft. stretch measure). At rear (perimeter line) web is square cut for 30 ft. width (1,150 meshes); Forward leading edge of floor is square cut 20 ft. (604 meshes); tapper cut 9,7 ft. for an ‘odd’ corner 2 bars 1 point (yyy meshes); then continues using a straight bar 32 ft. (zzz meshes). The angled-mesh tappers are difficult to count but continue forward until the align with the wings about 62 ft. forward of the perimeter line on each side.