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5/21/2012 | 2 MINUTE READ

Concrete canoe: University of Washington’s entry wins design prize

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Concrete canoe developed by the University of Washington's Civil and Environmental Engineering Dept. emphasizes composites use and won a design award at the annual Concrete Canoe Competition.

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2012 marks the 25th year of the Concrete Canoe Competition, sponsored by the American Society of Civil Engineers (ASCE, Reston, Va., USA) with funding from the ASCE Foundation and major corporate sponsors. Long a staple of college engineering programs, the competition gives student engineers a chance to make the improbable a reality. CompositesWorld spoke with the University of Washington’s (Seattle, Wash., USA) Jonathan Whiting, co-captain of that group’s canoe team and a senior in the UW Civil and Environmental Engineering Dept., to learn more about how UW’s craft was designed and built.

According to Whiting, the team first developed the canoe’s overall shape using “Taylor Standard Series,” a shipbuilding algorithm for optimizing hull shapes. FEA analysis of the hull was then conducted using MSC Patran software, from MSC.Software (Santa Ana, Calif., USA), for pre- and post-processing, while MD Nastran (also from MSC.Software) was used for the actual FEA analysis. Rhino 3D software supplied by McNeel North America (Seattle, Wash.) was used to develop the hull shape into a CAD format, which was then converted to CNC machining software language so that a female mold could be machined. Janicki Industries (Sedro-Woolley, Wash.), a collaborator on the project, donated $5,000 worth of CNC machining time on its large multi-axis gantry mill to cut a mold from high-density rigid polyurethane foam block, donated by General Plastics Mfg. Co. (Tacoma, Wash.), also a project supporter. “We chose to use a female mold to achieve a very smooth exterior finish, which really helped improve hull dynamics in the water. The high-density foam also provided stiffness needed to keep the hull within specs,” says Whiting.

A complex and dense concrete formula was developed, based on past canoe project experience coupled with extensive mix testing, which included white Portland cement, glass microspheres, lightweight sand aggregate, styrofoam beads, chopped polyvinyl alcohol (PVA) fibers and more. Whiting explains that because the concrete is weak in tension, the chopped PVA fibers helped improve overall strength, while continuous reinforcements, consisting of a lightweight, 0/+60/-60 E-glass stitched multiaxial fabric manufactured by Formax (Narborough, Leicester, U.K.) and supplied to the team by Janicki Industries, gave tensile support. The canoe’s hull was built up via hand layup by alternating layers of the concrete with layers of the multiaxial worked into the concrete mix. The canoe cured for a week under a tent to control humidity.

“The Formax material worked great,” reports Whiting. “Because of its light areal weight, it was drapable and easy to work with, something that we’ve had trouble with in the past because of the deep draft of the mold created by the straight sides.” The canoe, with a final weight of about 250 lb, was sanded, decorated with colored concrete and sealed with a topcoat. Whiting estimates that the project consumed more than 1,600 person-hours.

The team’s efforts earned it the top prize for canoe design at the northwest regional contest, but due to a technical error, UW did not advance to the national finals, to be held June 14–16 at the University of Nevada in Reno. But Whiting relates an anecdote that illustrates the high level of UW’s design and construction: “During the regional competition, the men sprint paddlers were getting ready for the race when a security patrol boat pulled up. They said we had to leave the area because there were concrete canoe races going on. We replied ‘We are part of that competition and this canoe is made of concrete.’ The patrol turned to leave and said, 'Oh sorry, we couldn’t tell.’” 

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