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TUNA FISHING SEA TRIALS PACIFIC OCEAN

TRIAL NO. 2 - F.V. BRENDA KAY

INTRODUCTION

The objective of this trial was to evaluate the operating performance of a USD device on a smaller longline vessel in a range of sea conditions, and to set 4,000 hooks through the USD under the normal fishing conditions.

It was hoped that during the fishing operations, severe weather conditions would allow the USD to be used in rough water so that the durability of the USD and performance of the attached paravanes could be evaluated.

Sea Trial Stages
Description
of the fishery
Trial 1
F.V. Daniel Solander
Trial 2
F.V. Brenda Kay
Trial 3
F.V. Atu S

 

The F.V Brenda Kay (TOBE International) was selected as a suitable vessel to carry out the sea trials.

VESSEL DETAILS

The F.V . Brenda Kay's steel construction and clear deck room made it a suitable vessel for the trial. Other vessels with small stern areas, overhead canopies, aft wheelhouses, or masts of insufficient height to position a block enabling a retrieval angle of forty degrees at the chute would require further modification of the chute set up to operate the device effectively.

The specifications of the vessel and the longlines used are provided in Tables 13, 14 and 15.
Table 13. F.V. Brenda Kay Specification

Length
Beam
Draft
Gross Weight
Power
Hull Material
Crew Number
13.8m
4.8m
2.3m
32.0t
171Kw
Steel
3
Table 14. F.V . Brenda Kay surface longline configuration
Mainline
Snoods
Floats
Basket size
30 mm(approx.)
950
58
25 hooks (approx.)
Table 15. F.V . Brenda Kay monofilament Longline dimensions
Mainline diameter
Snood diameter
Buoy line diameter
4.0 mm
2.2 - 2.0 mm
2.2 - 2.0 mm

LONGLINE SET-UP ON THE F.V . BRENDA KAY

The main line was routed from the longline reel on the port side of the vessel, across to the starboard side, through a block suspended from the wheelhouse roof, then at right angles down to the line shooter. The shooter was not used during the chute sea trials. The longline reel was always set on free wheel, with a tight main line over the stern. There was no slack line, as there is usually when using the shooter.

A buoy and one radio beacon is deployed from the stern and attached to the main line. Once the pole and radio buoys were clear and the mainline was slowly running off the longline reel, two additional floats were clipped onto the mainline before baiting snoods were deployed. One unusual feature of the F. V. Brenda Kay's fishing gear was the use of snoods as float lines. This allowed total freedom for the skipper to determine number of snoods in each basket.

Bait types used

Two types of bait were used for all the real-time at-sea trials:

  1. Sanmar (approx. 130 sanmar per carton)
  2. Squid (approx. 160 - 220 squid per carton)

Cartons of bait were left in the hold until the vessel had reached the start way point for the set. The cartons were then opened and the semi-frozen baits separated and placed into bins at the stern, thawing while the set progressed.

DESCRIPTION OF UNDERWATER SETTING DEVICE

Chute

The chute trialled was a 5.7 metre length of 6cm diameter steel pipe connected to the vessel in the same way as on the FV Daniel Solander, by a base plate bolted to the aft transom and contained by a pivot-arm and chute locking pins (see figs 6 and 7).

CHUTE DESIGN
Figure 9

The dorsal section of the tube had 2.5cm width slot along the full length of the tube. At the base of the tube a section of tube was cut away and flared to allow clear movement of the expelled bait. A split cowling was welded around the bait exit point to maximise the tube venturi effect.

On the base of the bait exit cowling a bracket was welded vertically, and through this, four separate holes were drilled allowing for four different points of connection for the paravane wire strop. The position of the wire strop used for all the F.V Brenda Kay trials was the hole furthest back from the dorsal snood groove down the length of the chute tube or lowest hole when the chute was fully deployed. Marks were painted on the chute at one metre intervals from the base. A record of the maximum and minimum number of marks visible above the water line was kept during setting. The angle of the chute in the water was estimated, and the maximum and minimum depth determined from this.

The top end of the tube was welded to the trough. The trough was half a metre in length and oval in shape, with sides approximately 10.0cm high. Water was fed in from the top of the trough via a connection point to the deck hose. The water then flowed from the top of the trough down its full length, through the point where the trough neck is welded to the chute tube and on down the tube to the bait exit point at the base of the chute.

Figure 10

Two steel plates were welded horizontally from a point above the weld that connects the chute tube and trough, and extended some 10 to 15cm above the trough floor into the trough. These horizontal plates were to act as line guides for the snoods. (see fig 10). The trough had a cut out section on the right hand side of approximately 5cm to allow easier use of the snood line guides.

Bait was fed into the trough allowing the water flow to carry the bait the full length of the tube. Once the bait had entered the tube, the crew member baiting the tube would allow the snood line to lie under the guide plate, preventing loose or slack line entering the snood groove before the bait had exited the base of the chute via the exit point and clearing the cowling. It was thought necessary for the snood line to exit the snood groove before the bait had cleared the exit and cowling to prevent the snood line from looping out of the groove and tangling at the exit point or lower on the paravane strop. It was also considered undesirable for the snood line to leave the tube before the bait, as the early release of the snood line could cause a bait to be forced prematurely from the tube, allowing a bait to be set at a shallower depth than the desired three metres.

Paravane

A similar flexiwing paravane to that used on the F.V Daniel Solander was used (See Fig 4 ), except that lead weights could be inserted into the nose of the paravane and an additional two attachment points had been drilled in the dorsal section.

Base Plate, Attachment and Hinge

The chute device was attached to the vessel using a similar base plate, hinge and and pivot arm as that used on the F.V. Daniel Solander . The chute base plate was attached to the aft transom horizontal stern plate, 80cm from the port stern quarter, at a height of 50cm above the deck plating.

Retrieval and deployment system

The retrieval system used for the trials on the F. V. Brenda Kay consisted of one double block shackled to the vessel's mast approximately 6.5 metres above the water line. Connected to a lug at the base of the chute feed trough was a single block with another shackle. An 8mm three strand rope was laced between two blocks and rigged to advantage, this block configuration is known as a Handy Billy or Jigger.

Figure 11

The chute was placed into the pivot arm and secured with the hinged collar with the paravane end of the chute extending over the stern. The paravane was then attached to the wire strop at the third attachment point from the front. The strop attachment to the chute was checked and the shackle tightened if necessary.

The single block was attached to the lug at the feed trough and the chute hoisted above the deck to about a thirty degree angle. The paravane was then deployed over the stern of the vessel and allowed to trail just below the sea surface in the vessel's wake, at this point the vessel would be idling into the weather or idling with the weather.

One person controlled the descent of the chute with the down haul length of rope from the Handy Billy block assembly. Up to three persons would assist by pushing from various positions along the chute length. It was difficult to get the chute moving through the pivot arm, the steel seemed to bite and grip with friction, due to the paravane's downward pull on the chute.

The position of the stern gantry and the height that the chute was mounted at the stern, meant that to haul the chute above the gantry would scrape the bottom of the chute over the gantry surface It was decided to go under the gantry, which meant that the chute's angle of entry was less than 45 degrees. This made it even more difficult to deploy and retrieve because the paravane was trying to keep the chute at a 45 degree angle.

Figure 12

Once the chute was fully deployed and the pivot arm guide bar had positioned itself between the two brackets welded to the base of the chute feed trough, the locking pin was inserted through all three and secured with a small clip. The chute was now completely secured to the pivot arm and the retaining collar of the pivot arm could be unpinned and folded out of the way. While the pivot arm retaining the collar was in place, it was impossible to apply baited snoods through the chute as the collar obstructed the snood groove.

FISHING PROCEDURE USING THE UNDERWATER SETTING DEVICE

Because the first few snoods in the bin were often tangled, it was decided to set the first two or three baskets by throwing the baited snoods out on the port quarter, as would normally be done. This also allowed the crew to get into a routine. The skipper would then fine tune the vessel's course to see that the chute was running at the correct angle and was towing well. Once these first baskets had been set, the crew started placing the baited snoods into the feed trough and allowing snoods to be set through the chute. This would continue until the completion of the set or until the skipper determined otherwise.

Once all the snoods available had been baited and attached to the mainline, the vessel speed was reduced. The mainline, still unwinding over the stern, was watched for an existing crimped join. Once a join was clear of the reel the vessel was reversed and the mainline cut, a loop was tied and the flag and radio buoys attached. Two floats were attached ahead of the end buoys for extra flotation.

Total hook numbers of both snood bins were counted before each trial set. In general the first set of each trip had the highest count due to tangled snoods being cut off, shark damage and general wear and tear during the fishing operation. As described, buoy ropes were also unbaited snoods and it was important to have an accurate count of these to work out how many to deduct from the total hook numbers set. A number of baited snoods were not deployed through the chute, but were thrown clear of the vessel in the usual style of deploying snoods. It became the practice that any snoods that looked tangled in the bins would be set in the traditional way rather than risk setting through the chute. Due to other tasks, only a rough estimate of these was kept.

The total number of hooks trialled through the device was calculated by counting the total number of hooks in the snood bins, and subtracting ten plastic lures (always thrown clear), total numbers of floats set, and total number of baited snoods not deployed through the device. On occasion, only a portion of the total available snoods were set through the chute due to problems with the snood tangling on the chute. An estimation was made of the total snoods remaining and back calculated for a total set.

Because the bait cartons were opened and the semi-frozen baits separated and placed into bins at the stern, little opportunity occurred to count specific amounts of bait used, due to the speed with which the crew separated the baits and the need to deploy the chute at the same time. Carton counts were used to determine bait numbers.

The USD configuration used on the F. V. Brenda Kay is shown in Figures 11 and 12.

RESULTS

Trial location and timing

There were two one day shake-down sea trials with the F. V. Brenda Kay's skipper, crew and USD developer, Paul Barnes, on board. The developer was present to install the device, fine tune paravane settings and answer any questions or concerns the skipper or crew might have. These trials took place on the 26.11.97 and 04.12.97 and four to five nautical miles seaward of the port of Tauranga. On the second shake down trial baited snoods were trialled through the chute.

Commercial fishing trials took place around an area called the Colville Ridge, 100 miles North-East of the port of Tauranga where the F. V. Brenda Kay was based. It was envisioned that two trips of up to five days fishing would be required to complete the trial requirements of 4,000 hooks (through the chute). However the fishing was considerably better than expected and the longest trip was only three fishing days due to the number of tuna landed and the relatively small hold. Table 16 gives the dates of the three trial trips:

Table 16: Timing of commercial fishing trials
Trip One: 27.11.97 to 01.12.97
Trip Two: 06.12.97 to 09.12.97
Trip Three: 11.12.97 to 14.12.97
Weather and sea conditions during the trials

The weather and sea conditions encountered during the two shake-down trials are summarised in Table 17. Both of these trials occurred during daylight hours.

Table 17: Weather and sea conditions - 'shake-down trials'

Date
Wind
Direction
Wind Speed (knts)
Swell Direction
Swell Height (M)
Cloud Cover (%)
26.11.97
SW
25
SW
0.5
90
04.12.97
SW
15
NE
0.5
100
During the trials setting was conducted at night between 2040hrs and 0523hrs - in accordance with accepted fishing practices developed to minimise sea bird capture. Table 18 summarises weather and sea information recorded during the commercial fishing sea trials. Weather conditions during the trial sets were more settled than would have been preferred, with only one of the five trial sets undertaken in wind and sea conditions of over 25 knots.
Table 18: Weather and sea conditions
Start Date
Trial Set No.
Wind Direction
Wind Speed (knts)
Swell Direction
Swell Height
28.11.97
1
NW
15
NW
0.75
07.12.97
2
SW
18
SW
1.5
07.12.97
3
NE
10
NE
0.75
13.12.97
4
ESE
25
ESE
2.5
13.12.97
5
NE
10
NE, SE
1.0-0.5

PERFORMANCE OF THE UNDERWATER SETTING DEVICE

Entanglements

Hook entanglements on the chute occurred during four of the five trial sets. Table 19 shows the number of entanglements recorded and if known, how the entanglement occurred.

Table 19: Number and causes of entanglement

1 0 2
2 683 3
3 817 2
4 648 7
5 876 0
In order to confirm where a snood was caught, the chute was retrieved back on board the vessel with the snood still attached to the mainline and the hook still connected to the chute at the fouling point. Due to the time involved and the number of crew required (at least two) it was deemed easier to haul the mainline back to the vessel until the offending snood could be reached. On a number of occasions particularly with rougher sea conditions, hauling the mainline back removed the pressure from the hook, and the hook came free. On the two occasions when hooks were observed in the entangled position, calm conditions would have contributed to the hooks remaining connected to the chute throughout the chute retrieval operation. The setting operation resuming again once the hook was freed and the vessel was up to speed.

Chute

On the first fishing trip while retrieving the chute, a weld three metres from the feed trough joining two lengths of chute tube together parted. The two lengths continued to be held by the angle-steel backing. The cracked weld prevented any further trials on this first trip. On arrival back at the port of Tauranga, arrangements were made through Moana Pacific's workshop to repair the weld. Alterations were also made to the retaining collar and the pivot arm and base of the feed trough to make alignment a simple operation.

Once these alterations were made, no further problems were experienced with the chute's durability. On the return to the port of Tauranga, on completion of trial trip number two, cosmetic alterations were required to the exit cowling and snood groove at the base of the chute tube, where observed hook-ups were taking place.

On the third fishing trip, during set six, under heavy weather conditions, the vessel was required to reverse back on the set gear five times, responding to individual hook-ups on the chute. During one of these reversals the extension bar of the vertical hinging was bent down about fifteen degrees at the point where the pivot arms horizontal hinging attached to the extension plate. This in no way damaged the chute or affected its performance during the final set.

On completion of trial trip three and the return to Tauranga, the entire device was removed from the vessel, including the base plate. No structural damage was noticed around the four bolt holes linking the device to the vessel, or any surrounding steel work on board.

The chute angle, when fully deployed, was consistently recorded at forty-five degrees to the stern of the vessel using a plastic angle measuring device taking the form of a protractor with a central measuring arm.

Trough

Sufficient water flow from the vessel's deck hose through the connection at the back of the feed trough was required to deliver baited snoods to sea level. The water flow was directed towards the point where the chute tube joined the neck of the feed trough. However, there was not enough water flushing around the sides of the trough, and baits stuck to the trough base. This was compounded by an additional difficulty of the chute being placed too far to port, requiring the crew person baiting to twist their torso from snood bin and bait to the chute trough.

The distance between snood bin and the chute encouraged the crew to lightly toss baited snoods at the chute feed trough rather than placing them in it, allowing the possibility of baits missing the feed trough altogether. While no baits were observed missing the feed trough, this situation cannot be ruled out as a possible cause of entanglement.

Paravane

Only one type of paravane, the flexiwing, was used during these trial sets. No damage was sustained by the paravane during these trials.

No difference was observed to the effectiveness of the paravane during differing weather conditions. During set six, when the most extreme weather conditions were encountered and the most snood hook-ups recorded, it is possible that the considerable movement of the vessel, both vertical and horizontal, through the sea-way effected the chute and snood interaction. It is also possible that the sea conditions effected the paravane performance through the rise and fall of the vessel's motion, though it was not possible to observe this.

During the trials, when the chute was fully extended in the deployed situation, it was noticeable that the chute had a 10 to 15 degree offset angle to starboard. This was also observed with the device trialled on the F. V. Daniel Solander, and was presumed to have been created by the propeller wash. The Skipper of the F. V. Brenda Kay was uncertain which way his vessel's propeller turned, it was difficult to tell from observing the propeller wash. However, as the direction of the offset angle was the same as for the previous F. V. Daniel Solander trials, it is assumed that the F. V. Brenda Kay's propeller had a clockwise rotation.

Deployment and retrieval system

The F. V. Brenda Kay was an ideal vessel for these trials, with a large uncluttered stern-deck, an uncluttered mast area with good height, and a hull of steel construction allowing for easy, clean attachment of the chute. There was also an ideal area above the deck to stow the chute when not in use. However, a number of difficulties were experienced during the trial sets.

1.An old, poorly maintained double-block was secured to the mast with a large shackle and then lashed into position pointing aft. A single-block (new) was laced to the double-block with 8mm polypropylene rope to complete the billy tackle. Had the double-block been in good working order, this block and tackle would have aided the speed and ease of the chute retrieval and deployment operation.

2. Another problem resulted from the force of the paravane pulling the chute down during deployment and retrieval. The problem arose when the chute feed-trough passed under the stern gantry. With the paravane forcing the chute to a 45 degree angle, the feed-trough had to be pulled down by one of the crew for the chute to clear the overhead gantry as it passed beneath it. During calm sea conditions this was not a problem, but when the vessel was influenced by any sea, the chute became difficult to control, even though it was contained by the pivot arm and collar. Retrieving/deploying the chute above the gantry, would have been dangerous in anything but calm seas.

3. After repeated settings, it appeared that there was an increase in friction between the steel of the pivot arm and the angle steel of the chute backing. This increase in friction was possibly due to rust build up or loss of paint, and was worsened by the loading caused by the paravane. This resulted in the chute sticking to the pivot arm during deployment/retrieval.

Performance of bait types used

Squid

Squid are an ideal bait for the chute as they are incredibly flexible, moulding themselves to any shape without being damaged or effecting the hook placement. Squid baits have the added ability, should they jam at the neck of the trough, to block the water flow allowing build-up to a volume where the water then forces the bait through the neck of the trough. Due to the size of the squid, they seemed to stay within the chute until being expelled at the exit point and would not readily clear the chute prematurely through the snood groove.

Sanmar

Sanmar are an imported, elongated bait fish resembling a garfish. Because of their long and slender shape, difficulties were experienced in getting the baits to move through the feed trough. If the baits were placed either side of the main water flow they had a tendency to remain where they landed due to insufficient water flow. Sanmar were hooked between the eyes and would land with the tail facing towards the neck of the trough. Because of their elongated shape and relative firmness, water would not build up behind them, requiring the person baiting to jerk the snood to reposition the fish into the trough's water flow. If the Sanmar landed directly into the main water flow through the trough, the sharp angle of the trough neck narrowing to meet the same diameter as the chute tube would cause these fish to often jam across the narrow neck, again requiring the snood to be jerked to realign the bait with the water flow. On occasions, three or four attempts would be required to align a bait.

DISCUSSION

Entanglements

From observations of the trial sets, a number of reasons for the baited snood hook-ups came to light:

1. It was assumed that a minimum snood length of ten metres would be trialled. However, snood lengths of approximately six metres and possibly less were present in the snood bins. Snoods are continually cut back because of shark damage or general wear and tear. The shorter snoods created tension on the hook while the hook was still in the chute tube, dragging the eye and shank out through the snood groove, the point, barb and kerb of the hook remaining inside the chute groove. The hook then dragged down the groove edge because of tension in the snood from the pull of the mainline and the vessels forward momentum, with the hook then jamming on the flaring of the exit cowling at the base of the device.

2. Sanmar baits, being long and thin were able to wash out of the snood groove if tension came onto the snood before the baited hook had cleared the exit point. If this occurred near the surface, there was a possibility that the forward wash of the vessels wake could wash the baited hook around the chute tube in a three-sixty degree turn. This bight of snood could then slide down the chute tube to the flaring and hook-up or slide further onto the paravane wire and hook-up there. A similar snag would occur if there was too much water from the deck hose travelling down the chute and washing the sanmar baits out of the snood groove.

3. A loop of snood nylon may occur through the snood groove above the point where the chute entered the water. As it is dragged under the water surface this loop is pinned to the under side of the chute tube by water pressure, slides the length of the chute tube and hooks-up on the exit cowling or on the paravane wire.

4. During trial set four, with winds of 25 knots or more and an estimated swell of 2.5 metres, five snood hook-ups were recorded. All of these hook-up points in or on the chute were unobserved and can only be guessed at. It is possible that the increased movement of both vessel and the chute, because of the size of the swell, were involved in these additional hook-ups.

5. A factor that influenced the results from these trials was the relative inexperience of the crew. It was their first season with the surface longline fishery. In contrast, trip number three had an experienced crew member who did a relief trip. This person's understanding of timing, baited snood placement and all round knowledge of the setting operation, had a direct effect on the lack of entanglements and successful outcome of the final set.

Safety issues

The use of the chute, including deployment and retrieval, it's use while deployed, and the need for it to be securely stowed on board on completion of each trial set uncovered a number of safety related issues:

1. During these trials, retrieval and deployment required three people; one controlling the rope through the blocks and two pushing and straining on the chute tube to move it through the pivot arm and collar. This should be a one person operation as other tasks required the crew's attention at this time.

2. For installation of the device on the F. V. Brenda Kay, the stern railing had to be removed. It was considered important that adequate railing surround the work area at the stern and that minimum amounts of railing be removed.

3. Concern was expressed that, with the chute in the deployed position and with five meters of chute tube and attached paravane trailing in the vessel's wake, the chute would interfere with the rudder or propeller should the Skipper want to reverse or stop suddenly. During the trial setting operations, it was necessary for the vessel to be stopped quickly due to snood entanglements on the chute. With reverse momentum, the vessel was pushed back along its own wake, therefore pushing the chute against the vessel's stern. No problems were encountered at these times, although the possibility of damage to the rudder or propeller was constantly considered.

4. There were few hand holds on the wheel house roof, and while hauling the chute onto the roof with the block and tackle, the chute could swing from side to side across the deck. This operation was potentially dangerous.

RECOMMENDATIONS

1. Entanglements

It is imperative that baited snoods not miss the feed trough when placed into it. Should this occur, it is possible for the baited snood, on falling into the vessel's wake, to tangle at some point on the chute. The feed trough could be redesigned with higher sides that would catch wayward baits and reposition them into the feed trough.

Shorter snoods result in tension between the snood clip on the mainline and the baited hook in the chute. The tension drags the hook shank out over one side of the snood groove allowing a hook-up on the snood exit cowling.

Too much water through the feed trough and chute may expel baits where the trough water flow meets the sea surface water level in the chute. The water is forced out through the snood groove forcing baits out with it. The narrowing of the snood groove would prevent baits being flushed out prematurely.

There needs to be good co-ordination between the person clipping snoods onto the mainline and the person deploying baited snoods through the chute. This prevents strain being applied onto the baited snoods in the chute, which has been identified as a cause of entanglement. Floats also need to be deployed in a controlled way to prevent float lines snagging on the device.

2. Positioning of the chute

The chute should be positioned on the stern so that the crew person does not need to stretch or twist their body in order to place baited snoods into the feed trough from their baiting position.

3. Water flow through the feed trough

A consistent, evenly spread water flow must cover the entire base of the feed trough. This would prevent the baits sticking to the trough base or jamming in the neck of the trough.

4. Paravane performance

With the exception of one trial set in rough sea conditions, only calm sea trials have taken place. The effects of high sea conditions on the paravanes action and the relationship between the paravane and increased hook-ups at the base of the chute under high sea conditions are still not known. The increased vessel movement by large swells may adversely effect the paravanes performance in some way.

5. The deployment and retrieval of the chute

The use of appropriate blocks to control speed and the ease with which the chute can be controlled through deployment or retrieval is necessary. Some form of friction-less pads or rollers positioned on the pivot arm allowing free movement of the chute backing through the pivot arm and collar would assist in deployment and retrieval of the chute.

6. Varying vessel configurations.

Chute storage, deployment and retrieval systems and position of deployed chute will need to be tailored to particular vessels because of the existence of aft wheel houses, canopies, stays, masts rigging and additional fishing equipment on different vessels.

Description
of the fishery
Trial 1
F.V. Daniel Solander
Trial 2
F.V. Brenda Kay
Trial 3
F.V. Atu S
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