MONTEREY, CALIF.-About 13,000 pounds of resin and 7,000 pounds of fiberglass form the fiber-reinforced plastic shell liner and supportive ribs for Monterey Bay Aquarium's soon-to-open Outer Bay exhibit. The exhibit's massive, primary viewing window - an acrylic slab that currently is the world's largest such window - weighs 78,000 pounds. ``This tank has the most plastic products in any aquarium,'' John Christian-sen, project manager with Rhodes/Dahl Inc., said in a telephone interview from his current project in Mystic, Conn.
Rhodes/Dahl, now based in Charleston, S.C., was hired to oversee all aspects of the aquarium project.
Described as the world's first large-scale open-ocean exhibit, Outer Bay replicates the habitat of seven species of sea life in a 1 million-gallon concrete tank. Visitors will view ocean sunfish, blue and soup fin sharks, bonitos, California barracudas, yellowfin tuna and a green sea turtle. Members and donors will preview the $57 million exhibit in February; it will open March 2.
Planning for Outer Bay began in 1989. A structurally supported, FRP design was selected for the liner and ribs. Plastic was the material of choice, Christiansen said, because metal tendsto corrode in sea water and the process of corrosion causes electrical fields that affect sharks' navigational and food-finding senses.
William Kreysler suggested the liner design after looking at concepts using heavier materials. His Penngrove, Calif., firm, William Kreysler & Associates Inc., tackles large, single-use, construction-related projects, usually of fiberglass.
At an early stage, Kreysler and the aquarium's project team toured Reichhold Chemical Inc.'s development laboratories in Research Triangle Park, N.C.
``We explained what polyesters are and where they can be used,'' said Bill Schramm, Reichhold's director of global product management. ``Their application [at Monterey] is mostly mechanical in nature.''
The aquarium selected Reichhold's corrosion-grade isophthalic-based Dion 33434-00, which qualifies under military specifications and for Food and Drug Administration-approved applications.
``Sea water is a mild condition for this material,'' Schramm said.
Vetrotex CertainTeed Corp.'s M127 chopped-strand mat was used for the liner panels, and Knytex Co.'s A260 woven warp unidirectional strand fabric and Vetrotex CertainTeed 518-10 stitch mat formed the structural ribs, or supporting beams, according to Bill Hoekstra of Composite Materials Inc. in West Sacramento, Calif.
Kurt Jordan, a finite-element-analysis engineer in Mill Valley, Calif., evaluated alternative loads and pinpointed stress levels in the self-supporting shell. FEA is a method that creates structural computer models from small elements, or plates, to form the entire shape of a finished product.
Jordan borrowed computer-design techniques from those used to create aircraft, spacecraft and America's Cup yachts and sails. The aquarium's goal: identify the best laminate for the least amount of money.
The aquarium tank is shaped like an oval salad bowl - if a bowl can measure 35 feet deep, 90 feet long and 52 feet wide - and was built with 1,350 cubic yards of concrete.
The liner's shape resembles the interior of a ship's hull with the finished materials on the inside, concealing the bracing and cross ribs. Sea water circulates on both sides of the liner.
``The shell has overlapping molded FRP panels that are not too different from the shingles of a house,'' Kreysler said. ``The panels came in four slightly curved shapes and could be flexed into position. Serge Labesque, our vice president for product design, figured the whole thing out.''
Mexican glass tiles are mortared to the surface of the panels with epoxy. Aquarium managers were reluctant to use any type of gel coat because of prior abrasion problems caused by cleaning.
The Mosaicos Venecianos de Mexico tile factory in Cuernavaca produced about 1.28 million inch-square, dark-blue tiles that were affixed on 8,900 foot-square pieces and eventually installed on the FRP panels. The FEA simulations calculated the weight of the tiles and how much the fiberglass could deflect without delaminating the tiles.
Nippura Co. Ltd., an affiliate of Sumitomo Chemical Co., fabricated the primary viewing window at its plant in Takamatsu, Japan. The 13-inch-thick acrylic window is 17 feet high and 561/2 feet wide.
In addition, Nippura made the two other viewing acrylic windows and performed the installation under a $1.8 million contract. Nippura Co. Ltd. was known until Jan. 1 as Nippura Keiko Setsubi Co. Ltd.
Panel and tile installers actually floated to work.
``We filled the tank with [fresh] water gradually, and worked on floating wedges of plywood-covered expanded polystyrene foam,'' Kreysler said. ``We went up putting on panels, and we came down putting on tiles. It worked like a charm.''
Near the end of construction, contractors worked to seal concrete leaks, complete the liner shell, balance flows with dye tests, set temperatures and run the closed sea water system.
``We needed the tank done and tested well in advance of September for tuna collecting,'' said Randy Hamilton, life sci-ences exhibit coordinator. ``Yellowfin tuna do massive migrations in the ocean ... and they are here only a few months. We made it just in time.''
Opened in 1984, Monterey Bay Aquarium projects a total 1996 attendance of more than 1.8 million and plans next to develop a deep-sea exhibit that will open, probably with more plastic elements, in 2000 or 2001.