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Final Report  

AIMAP Project # 2010-G02               

Prepared by Chantal Gionet
Coastal Zones Research Institute, Inc.
Shippagan, N.B.
gionetc@umcs.ca

Submitted by
Donald Jaillet
Jaillet Aquaculture, Inc.
Bouctouche Bay, N.B.

March 2011

Table of contents

Introduction

The American oyster industry in New Brunswick was revolutionized by the introduction of suspension techniques for cultivating oysters. In 2008, New Brunswick had an estimated inventory of 100 million oysters growing in the water column. Many of these oysters had been reared in the OysterGro™ system (www.oystergro.com). In southeast New Brunswick, this technique is used by nearly 80% of oyster producers involved in aquaculture.

The OysterGro™ unit consists of a vinyl-coated wire mesh cage that can hold six Vexar® bags on two levels. The cage is mounted on rectangular floats that allow for two different positions in the water: the submerged position – where the Vexar® bags are maintained in the water at a depth of 6 to 12 inches from the surface; and the “flipped” position” – where the unit is turned over to expose the Vexar® bags to the sun. In this position, the bags have no contact with the water, which allows the cages and oysters to dry out. This drying process is used to control biofouling (the accumulation of marine organisms on the oyster shells) as well as secondary spat.  

Infestation by biofouling organisms is one of the shellfish industry's most significant challenges. Biofouling organisms compete with oysters for food and affect their growth and even survival, as well as their overall appearance. Even more importantly, if not managed correctly, marine biofoul can have significant consequences on the practices and productivity of an aquaculture farm. As markets become increasingly demanding, farms must be able to produce superior quality oysters. Current practices associated with the OysterGro™ system involve flipping the units to expose the bags and cages to the sun. This process has proven successful in controlling biofoul. However, the flipping process remains a labour-intensive and physically demanding activity.

Given that it operates in a very productive region, Jaillet Aquaculture in Bouctouche Bay has to contend with marine biofoul. The company used other farming systems in the past, but they were not very successful in controlling this problem. With the OysterGro™ system, the company has 100% control over biofoul. To maintain this control, it may have to flip the cages 7 to 10 times per production season (May to November). It takes 2 or 3 men to manually flip a cage 360°. Cage weight varies with oyster age class, but averages 100 to 300 pounds.

In 2009, Jaillet Aquaculture had an inventory of approximately 750 OysterGro™ cages at sea, which represents 4 500 Vexar® bags, for a total of 2 million oysters in production. Jaillet Aquaculture has 3 seasonal employees. This is typical of small- to medium-sized businesses, which is 85% of the industry in southern New Brunswick. It is difficult for aquaculturists to develop their farms and produce more oysters given the lack of automation, not to mention people willing to perform such physically challenging work. Furthermore, cage flipping damages the oyster fringes, reduces annual growth, and extends the period required to reach commercial size.

There is no device on the market that can automatically flip the cages. Such a device would encourage site expansion, increase oyster production, and reduce production costs, thereby increasing profits. The purpose of this project is therefore to develop a prototype for a flipping device for OysterGro™ cages.

Work performed

Project phases

This project was divided into 6 phases:

  1. Study of the manual flipping process
  2. Prototype concept and validation
  3. Prototype design and construction
  4. Prototype test at sea
  5. Redesign and retest at sea
  6. Final test of the prototype with a study of the impact on oysters and cages�

Phase 1

This phase involved studying the manual flipping process currently practised by growing operations using the OysterGro™ system. The technical challenges involved in designing the prototype were also examined. This phase was intended to enable the engineers to understand the flipping process and how the cages are attached and anchored. Furthermore, the team familiarized itself with the cage structure and buoy types (there are two types used in the industry) and the set-up of farming sites using this cage. Phase 1 was also used to collect as much information as possible in order to identify all the technical challenges to be considered in designing a prototype. A number of companies were approached to participate in this prototype construction project. The first company selected had to increase its production costs and substantially exceeded the budget. Donald Jaillet had to find another company in order to be able to deliver this part of the project. The choice fell to Atlantic Systems Manufacturing, Ltd. of Charlottetown, Prince Edward Island. This company has several engineers with more than 20 years of experience in constructing materials for the agrifood industry, including softshell clams, crab, lobster, mussels, scallops, salmon and many others.

Engineer's visit

Given the change in companies for constructing the prototype, the project began a little later than planned. The first visit of the engineer to Bouctouche Bay and Donald Jaillet for Phase 1 took place on June 24, 2010. This visit was a first meeting with engineer Mike McKenna and a technician from ASM. They learned about the technique for manually flipping OysterGro ™ cages and the barge that would be used to install the prototype. The ASM people also had an opportunity to seek the advice of other aquaculturists (Maurice Daigle and Armand King). They departed with an OysterGro™ cage and attachment lines in order to conduct tests on their premises. 

Phase 2

This design and validation phase involved conducting small-scale tests of the different processes envisioned, with a view to the configuration of the lines and the structure of the cages, the flipping process and the capacity to redistribute the oysters within the Vexar® bags. The prototype should also reduce oyster shell breakage to a minimum, while ensuring cage stability during the flipping process, as well as when returning the cage to the water.  

The ASM people went back to their offices after the visit to Donald Jaillet in order to begin the tests. Details of each test are appended to this report (Appendix A). Their first idea was to build a system similar to that used in canning plants. The system would lift the cage out of the water and flip it, but this required too much force, and the cage began to twist out of shape. After these tests, there were still two alternatives to be studied. The first was to build a conveyor device to tilt and turn the cage. The second involved working with the cage directly in the water. Tests were conducted on flipping under water. Using water meant placing less stress on the cage. Numerous calculations and tests (Appendix A) were conducted before returning to Donald Jaillet's site for a final validation of underwater flipping on August 17, 2010. 

Following this last visit, drawings of the flipping system were prepared and a prototype built in order to test the principle. On October 29, 2010, there was a visit to PEI to see the work in progress. The idea behind the prototype is a three-finger frame that sits on the cage between the floats and pushes it under the water and turns it. This frame will be run by a hydraulic motor with a three-position valve controlled by an operator. This method will also allow the oysters to be levelled out after rotation by shaking the cage out of the water. The frame will then remain in its original position to await the next cage.

Phase 3

Once the concept had been validated, the prototype was built. Certain specifications had to be considered, such as:

All these criteria were considered in constructing the prototype, with the exception of point d. The device that flips the cages cannot be placed on absolutely any platform without major modifications to ensure safety and stability. It was therefore decided to build this prototype with two pontoons. 

Construction of the prototype

The prototype was built in the fall of 2010 pursuant to the established specifications (Appendix).

Work to follow (2011-2012)

Phases 4 to 6 remain to be completed in the upcoming growing year. These phases involve the first tests at sea with the prototype, making any necessary modifications, and a full test through an entire season. This will evaluate the impact on oysters of automatic versus manual flipping. This last part will be the responsibility of the mollusc research group at the Coastal Zones Research Institute Inc. in Shippagan, in collaboration with the team at Jaillet Aquaculture, Inc.

Conclusion and Discussion

A prototype has been constructed to automatically flip OysterGro™ cages. Flipping will be performed entirely under water. This is a very attractive element because it should reduce stress on the oysters, and in particular, limit fringe breakage. This prototype will offer an advantage to the company by flipping cages without significant physical effort. It will also demonstrate whether better growth can be achieved.

Acknowledgements

This study was funded by the Aquaculture Innovation and Market Access Program (AIMAP), the National Research Centre, the New Brunswick Department of Agriculture, Aquaculture and Fisheries and Enterprise Kent. A big thank you to the entire Jaillet Aquaculture team: Donald Jaillet, Alberta Cormier and L�onard Caissie; as well as the CZRI mollusc research team: M�lanie Degr�ce, Jos�e Duguay and Mathieu Landry, for their great work and cooperation.

APPENDIX A

OysterGro Cage Flipper Project
Jailett Aquaculture Ltd.
Final Report

April 2011

Submitted by:
Jaillet Aquaculture and Atlantic Systems Manufacturing Ltd.
38 McCarville Street Charlottetown, PE Canada

OysterGro Cage Flipper Project

In May 2010 Atlantic Systems Manufacturing Ltd. was contacted by Ronda Dillon, Industrial Technology Adviser from National Research Council in Moncton NB regarding a project to design an automatic flipping device for OysterGroTM cages for the oyster industry in New Brunswick. A follow up meeting was held on May 21 at the office of Atlantic Systems Manufacturing Ltd. In Charlottetown, PE between Mike McKenna P.Eng., Ronda Dillon and Donald Jaillet representing Jaillet Aquaculture Ltd. The project background, objectives and funding were discussed. On May 28, 2010 Atlantic Systems Manufacturing Ltd. forwarded a proposal with three progressive phases and budget prices for each.

The contract to develop an automatic flipping device for OysterGroTM cages was signed between Jaillet Aquaculture Ltd. and Atlantic Systems Manufacturing Ltd. on June 24, 2010 in Bouctouche NB. On that day Mike McKenna and Stephen Matheson from Atlantic Systems Manufacturing Ltd. travelled to Bouctouche and met with Ronda Dillon, Donald Jaillet and Chantal Gionet, MSc. a biologist with Coastal Zone Research Institute Inc. A boat tour of Jaillet's oyster growing operation and another grow out operation was organized where the layout of the growing cages on the lease were observed. The current method of manual flipping of the OysterGro cages was demonstrated. Video and still pictures were taken for future reference. Donald showed how the cages were tied together and anchored in the bay. An OysterGro cage and main rope line with dropper lines for the cages were taken back to Atlantic Systems Manufacturing Ltd. for design purposes.

Donald also explained how the cages are regularly hauled out of the water to remove the growing bags and redistribute the oysters. A hauler pulls on the main rope, which the cages are tied to and brings the cages up an inclined ramp on a barge to a table where the work is preformed.

The first flipper design was based on this assumption that the cages could be removed from the water using a hauler and ramp similar to the existing system and then flipped over and slid down a ramp back into the water. The proposed flipping portion of the design was based on a can rotating system that is used in the canning industry. A prototype was assembled with an inclined chute to slide the cage up with a rope hauler to pull the main rope. Once up the incline ramp, a guide was added to begin lifting up one side of the cage as it was hauled forward by the rope. A large amount of force was required to pull the cage up the incline ramp. When the cage began to incline up the guide on one side, the cage began to distort or twist. Stainless steel and various plastic strips were tried to lessen the friction but still there was too much stress and distortion on the cage while flipping.

Other methods to lessen the forces on the cage as it was hauled up the ramp were investigated. An inclined conveyor would eliminate this problem. However the actual flipping process caused the greatest stress on the cage and this could not be overcome by conveyors alone. Rotating the cage around a fixed or slow rotating pipe showed some promise but guiding the cage and controlling the speed of the rotation were large obstacles to overcome in the design.

A simple solution to the distortion problem is to keep the cages in the water. The next design proposed was to force the cage and floats under the water with a pipe between the floats, then allow one side of the cage to float up and have the cage rotate around the central pipe thus flipping it. Again the stresses on the cage and floats had to be accessed when it is submerged. The advantage of the method is not having to removing the cages from the water, less movement of the oysters in the bags and using the floats' buoyancy to turn the cages. A couple of conveyors may be needed to help submerge the cages, rather than pulling them with the main rope.

A small scale replica of the cage was built and trials of submerging and rolling it over underwater were done. The test proved the cage could be rolled half way and with a guide will turn over completely.

The next step in this design was to attempt to replicate the flipping using an actual OysterGroTM cage. First the amount of force required to sink the cage had to be calculated. The weight of the cage with floats and empty bags is 64 lbs (29 kg). Theoretical calculations determined the two floats to have a buoyancy of 370 lbs (168 kg) in salt water. The cages have six Vexar oyster bags with an average growing weight of 22 lbs (10 kg) per bag giving a total cage weight of 196 lbs (89 kg). Thus under normal growing conditions we need 174 lbs (79 kg) force to submerge the cage.

In lieu of oysters, the Vexar bags were loaded with 22 lbs (10 kg) of gravel and placed into the cages for our testing purpose. The cage and bags were taken to shallow salt water bay to do an actual buoyancy calculation and test the ability to submerge the cage and rotate it around a pipe placed between the floats. Bags of gravel were placed on the cage until it submerged. The capacity of the floats was determined to be 440 lbs (200 kg) so subtracting the cage, bags and oyster weight, the actual force required to sink the loaded cage was 244 lbs (111 kg).

For the next test, a 6" PVC pipe was placed between the floats and pushed down to sink the cage under the water. Once the cage was submerged it was rotated around the pipe. The cage turned 90E with little effort but at that point all the gravel rolled to the bottom. It took much more effort to turn the cage the next 90E and if it was released it flipped back to the 90E position. When the cage was flipped 180E and shook to spread the gravel evenly in the bags the cage floated correctly. The gravel being loose in the Vexar bags caused the problem.

To continue the test, the Vexar bags were removed from the cage. The empty cage was submerged and then rotated around the pipe. The cage flipped as predicted and without the Vexar bags filled with gravel, it floated level after flipping.

On August 17, 2010, Mike McKenna and Stephen Matheson travelled to Bouctouche and met with Donald Jaillet and Chantal Gionet. Once on the water, the manual method of flipping was again observed with Stephen participating in the process. A test using the pipe to submerge and rotate the cage was attempted with some success. It was difficult to sink the cage and rotate the cage from the work boat due to the reactive force pushing the boat away. The trip to Donald's site confirmed that the flipping of the cages must be done in the water and that the force to submerge the cage will have an effect on the work boat.

The concept formulated from these observations was to use a pontoon raft where the cages run between the pontoons. A centrally located pipe would push the cages under the water, a guide would begin to rotate it and then allow the cage's buoyancy to partially flip it. Some mechanical assistance will be needed to complete the flip. One challenge will be in re-distributing the oysters in the bags to have the cage float level after flipping. Some type of a shaking system working on the top the cage will be needed.

After a review of the trials to date and discussing the problems with moving and rotating the cage around, a fixed pipe under water an alternate concept was proposed. The idea was to use a frame to push the cage under the water and rotate it. The frame will be rotated using a hydraulic motor with a three position valve controlled by an operator. This method would also allow levelling of the oysters after rotating by shaking the cage out of the water. The frame would then be rotated back to original position to wait for the next cage.

This system could be attached to the side an existing boat but that could potentially cause stability problems. A pontoon raft where the cages pass between the pontoons and the flipping to occur there would be much easier to keep stable.

On September 13, 2010, Mike McKenna travelled to Bouctouche for a meeting at the Department of Agriculture and Aquaculture office. Present at the meeting were Donald Jaillet, Chantal Gionet, Ronda Dillon, Florence Albert - Department of Fisheries and Oceans, Marcel L�ger - Department of Agriculture and Aquaculture, Marie-Jos�e Maillet - Department of Agriculture and Aquaculture and Marie-Paul Robichaud - Entreprise Kent. An update on the project was presented along with costs to date. The concept of a rotating frame to turn the cage was introduced along with preliminary drawings. The concept was well received by all and was given tentative approval to proceed subject to approval of the construction budget. On September 16 an update of costs to date for the project and a budget for the new prototype were sent to Donald Jaillet as follows.

The approval to proceed on the concept using the hydraulically driven frame to rotate the cage on October 4, 2010. Design and drawings began immediately. A large roll-on waste container was leased and the end door was welded to make a water tight test tank. The frame to rotate the cage was fabricated from stainless steel pipe and mounted at the top of the tank. A hydraulic motor with chain and sprockets were installed to power the frame.

The first tests showed problems with the chain size, hydraulic motor size and frame weight. A larger chain was selected and a large hydraulic motor ordered. Due to delivery problems a 10 HP electric gearmotor replaced the under sized hydraulic motor so testing could continue. The subsequent tests revealed two problems. The cage was observed to occasionally pop out of the frame when initially being pushed underwater. Then when the cage was almost rotated 180E, the buoyancy of the cage caused it to shoot out of the water and sometimes flip back over to its original position. The frame was redesigned and modified by adding an additional strut and staggering the height of the struts to push the outer edge first. The electric gearmotor speed was too fast so the chain sprocket ratio was changed to slow it down. The next tests proved that these changes improved the flipping process.

On October 29, 2011 Donald Jaillet, Chantal Gionet, Florence Albert and Marie-Paul Robichaud traveled to PEI to observe testing of the prototype flipper in the test tank at Atlantic Systems Manufacturing. The flipping of the cages was successful. All comments on the flipper were positive and the consensus was that design was on the right track.

The next stage in the project was to mount a flipper to a boat to do sea trials. Discussion turned to what type of boat would be best to use. Mounting the flipper on the side of an existing work boat could lead to stability problems. A pontoon raft that allowed the cages to pass between to be flipped was chosen as the most logical choice.

Florence Albert approved research into the design and construction of a pontoon raft to mount the OysterGro cage flipper on November 8, 2010. She suggested contacting Alain Doucet
MITTC from CCNB Campus de Bathurst. Alain agreed to submit a proposal and quotation for the design and drawings of a pontoon raft. After approving the objective statement on November 22, 2010, a preliminary design was submitted on November 29, 2010. An estimate of costs for the fabrication and concept drawings for the raft were emailed to Jaillet Aquaculture on December 5, 2010.

Donald approved the quotation and work began immediately on finalizing the drawings and acquisition of materials. Construction began on December 7 and the pontoon raft was completed on December 16, 2010. A new lighter aluminum flipper frame was built and installed. The hydraulic pump, motor, chain & sprockets, controls and hoses were installed and tested. A guide was installed between the pontoons under the raft deck to direct the OysterGro cages to the flipper.

Donald made plans to inspect the finished raft on December 22, 2010 but a salvage winter December 30, 2010 Donald traveled to PEI and approved the completion of the pontoon raft and the OysterGro flipper. In February the raft was transported to Bouctouche with trials expected in May 2011.