Tasks Accomplished: 4) Purchase Materials and Construct Nurseries
Jack Blake experimented with three grades of plastic wood before deciding on "Choice Deck" for construction of the bins.
4) Purchase Materials and Construct Nurseries --
1999--As soon as possible after the signing of the grant award contract, materials for construction of the nurseries were ordered. Mr. Blake assembled materials lists, compared prices, and, after receiving Mr. Karney’s approval, placed the orders.
Mr. Blake solicited samples of four different materials (pressure treated lumber and three grades of plastic wood) from which he constructed prototype bins. Although the pressure treated lumber was determined to be the lightest and easiest to work, concerns about the possible leaching of preservatives from the wood and no clear scientific data on its possible impacts on small shellfish seed, led to the decision to construct the shellfish seed holding bins out of plastic wood. The three grades of plastic wood included one which was 99% polyethylene which would not float and was too dense for staples to penetrate; the second was a 50-50 mix of oak and polyethylene and the third, "Choice Deck", was a 50-50 mix of red cedar chips and polyethylene (brochure attached). Of the three grades of plastic wood used to construct the prototypes "Choice Deck" by Weyerhauser had the greatest holding power for the staples. It was selected and an order was placed.
Jack Blake experimented with three grades of plastic wood before deciding on"Choice Deck" for construction of the bins Stainless steel (316) rods and stock for construction of the bin handles was purchased and machined in Mr. Blake’s shop. Fabrication of the handles required custom bending jigs, torches, welders, a drill press, and a power hack saw which Mr. Blake provided to the growers. The specialized equipment necessitated construction in Mr. Blake’s shop. Fabrication of the handles was a two man job and Mr. Blake worked with each grower to build 25 handles apiece.
When the plastic wood stock order came in, arrangements were made to use the Edgartown Town Barn as the site to cut, route, and assemble the wood into the bin frames. The growers donated three table saws and a radial arm saw to work the wood. Free use of the work place including electricity and heat was arranged by Paul Bagnall, the Edgartown Shellfish Constable/Biologist. During several weeks of marathon work sessions, the growers collectively cut and machined with tight tolerances 6,780 pieces of plastic wood for the construction of 455 seed nursery bins and 280 covers. With custom jigs, the wood sections were secured together with stainless steel screws to form frames. Polyethylene and plastic mesh of various grids was ordered, cut to size, and attached to the frames to complete the bins. The growers assembled the bins as they needed them. Construction of the bins was completed over the less busy winter months of 2000.
Superior grade (ACQ) pressure treated lumber which does not contain arsenic was selected and purchased for construction of the upweller units. Like the bin frames, the lumber was cut and assembled collectively during scheduled work sessions at the Edgartown Barn. An assembly line system was followed as it was the most efficient means of constructing the upweller nurseries. The upwellers were framed; reinforced with galvanized hardware; fitted with styrofoam flotation; sheathed with pressure treated plywood; and painted with epoxy, water immersion paint. Just prior to launching, polyethylene sheeting was attached to the outside surfaces of the upwellers to aid in the removal of biofouling at the end of the season.
Stainless steel (316) rods and stock for construction of the bin handles was purchased and machined in Mr. Blake's shop. Fabrication of the handles required custom bending jigs, torches, welders, a drill press, and a power hack saw which Mr. Blake provided to the growers. The specialized equipment necessitated construction in Mr. Blake's shop. Fabrication of the handles was a two man job and Mr. Blake worked with each grower to build 25 handles apiece.
All upwellers were fitted with a 2 1/2" galvanized pipe which served as a support and drain for a wet sink. The pipe drain was designed to pass through both the top deck and bottom of the upweller unit, thereby allowing the silt and feces to bypass the seed bins.
The pipe support presents a minimal surface to the wind and waves thereby streamlining the deck surface.
Three upweller units were completed, launched and tested during the 1999 growing season. Another was about 90% completed by the end of the summer of 1999. The delay in the start of the project from 1. January to 1. March eliminated eight weeks of construction time for the growers. Only during the winter months, when the growers’ schedules are slow, can they find time to do the construction. Despite working weekends, holidays and evenings, they could not make up the time lost in January and February of 1999.
2000--Only one of the four units tested during 1999 was hauled for the winter. The nurseries which remained in the water were observed to be used by basking seals over the winter! Despite a cold January with lots of ice, the units that were left on their moorings over the winter fared well with little ice damage save some ice abrasion of the paint and some damage to several of the hatch covers. Growers observed that because of the nurseries’ low profile, the shifting surface ice had a tendency to override the units rather than drag the nurseries off their moorings. After observing the potential for ice damage during the winter, however, most growers plan to haul their units before the coldest weather of the coming winter.
Tom Berry hauled his nursery on 10. December, 1999. Unlike the launch of the new, clean unit which was accomplished with a boat trailer, heavy biofouling of the unit over the summer necessitated the use of a boatyard’s lift to haul the structure. Although the polyethylene sheeting stapled to outside surfaces of the unit lessened the labor of removing the biofouling and cleaning his upweller, Mr. Berry opted to coat the outside surfaces of his nursery with copper bottom paint prior to relaunching it in 2000 in hopes of preventing the heavy fouling.
Before he relaunched his unit on 12. May, 2000, Mr. Berry made several modifications to his nursery based on his first season’s experience. Mr. Berry sought to improve the flow rate through his unit with the addition of a number of vents. On each side of the nursery, he added seven vents. The holes were set two feet apart right below the water line and just below the tops of the interior bins. The holes were fitted with sections of 8 inch pvc pipe so as to create a venturi effect drawing more water out of the unit and thereby increasing the flow of seawater past the cultured oyster seed. Mr. Berry estimated that the vents improved discharge capacity by 30-40%. He also added four 4 inch holes across the top of the front baffle scoop and two vents in the stern corners of the unit to improve flow rate. The stern vents aided in the flushing of anaerobic debris that was observed to settle in the back corners of the nursery. He reported periodically stirring up the accumulate muck with a power washer which was then successfully flushed via the vents from the nursery.
Some of the growers noted the difficulty they experienced trying to lift the stacked bins of shellfish onto the decks of the units. Tom Berry equipped his upweller with a portable gaf-rigged boom which could be moved about the nursery and help prevent back injuries. He also equipped his nursery with a " push pad" and chock in the stern of the nursery to improve control of the unit when moving it with a push boat.
Another modification that Tom Berry made to his upweller nursery was the addition of two "bumper fences" which were installed on both sides of the nursery and prevented boats tied to the nursery from being pushed up onto the deck of the nursery by the wakes of passing boats. Jack Blake cautioned, however, that the fences may catch the wind and make the tidal nursery less likely to maximize the capture of the tide driven currents.
The final two units were completed in late winter in time to be used during the 2000 growing season.
Grower Roy Scheffer, and Edgartown shellfish managers Paul Bagnall and Warren Gaines completed the nursery they would share to grow quahog seed for the Edgartown public stock enhancement program and oyster seed for Mr. Scheffer’s private oyster farm. Their upweller nursery was launched and moored in Katama Bay on 25. June 2000.
Jack Blake, who designed the original prototype and provided training sessions in 1999, found time to complete his unit in the spring of 2000. He, like Mr. Berry, equipped the new unit with vents to improve the flow of seawater through the nursery. He installed twelve 12 inch polyethylene pipes along one side of the nursery. As his new nursery would be tied along the original prototype, the vents could only be put on one side. He also reported a dramatic increase in the flow of water through the unit which he attributed to both the increased area for discharge and the venturi effect of the slanted vent pipes in his modified "turbo charged" shellfish nursery. Like Mr. Berry, Jack Blake opted to use copper bottom paint to control biofouling on his nursery. In addition to the outside surfaces, he also painted some of the interior surfaces. Biofouling in the interior of the unit decreases the flow rate. Mr. Blake noted that he needed to add 700 pounds of additional flotation to the nursery prototype to support the additional weight of fouling organisms which attached to the unit and grew over the course of the 1999 growing season.