Concrete canoe complications cause consternation, crisis

Every few years, a group of students pours enormous energy for about four months into designing and building a concrete canoe for an ASCE sponsored competition. In past meets, MIT teams tended to score well in the design, construction, and theory sections of the contest, and have ranged from speedy to sluggish in the actual races on various rivers and lakes.

After hundreds of hours of work since January 2002 by a dedicated group of students, the MIT concrete canoe suffered a fatal crack less than a week before the regional competition in May. Marc Washington '03 recalls, "The boat was almost finished. Three of us were putting on the final coat of paint. Usually about 10 of us worked on it, making it easier to move it around since it weighed about 300 lbs (136 kg). With three of us, it was pretty difficult.

We tried to lift it up to paint the other side, with one person on each end and one in the middle, and it buckled like a beam, cracking in the middle. After it happened, we just sat and stared at it for an hour, thinking, 'Gosh, what did we do??'"

Racking their brains for solutions, the trio eventually decided that nothing could repair the damage fast enough and also comply with the contest's stringent rules. Like real engineers, they decided to just learn from their mistakes.

The group had begun work during IAP (Independent Activities Period, in January), with the construction of a mold copied from a canoe in the MIT boat house. Participants came from a variety of courses, including four from CEE Washington, Mike Chen '03, Carl Frank '03 and Steve Alpert '05. Previous canoes had been built in 1989, 1990, 1991, and 1998, but all the participants have graduated, leaving nobody with any previous experience besides faculty advisor John Germaine. Washington says, "Everything was hard, because we were so uncertain how it would turn out." The group constantly found itself in the position described by Washington as, "'OK, we did this step, it works, and now onto the next step. We don't know how to do it, but we can figure it out.' Getting as far as we did was a feat in itself." On its test run in the shallow moat girding the MIT Chapel, the canoe floated properly, even when filled with water as required by the contest rules.

For the display and required technical presentation, "we were going to call it 'The Heavyweight,' with a whole boxing theme," says Washington. "We were going to put a cross section of our boat in a little boxing ring decorated with boxing paraphernalia." Like the boat, the display was on the verge of completion before the fatal crack occurred.

This year's boat had a particularly smooth hull because the students chose a female mold, where the mold is on the outside with the concrete placed against it. In previous years they used male molds, where the mold is on the inside with concrete covering it. "Having a female mold cut down a lot of the work. With a male mold we would have had to sand the boat to make it smoother. We were told that it would be harder to make the female mold as opposed to the male mold, but we didn't run into any problems," notes Washington.

The basic construction materials were half-inch-square steel mesh for strength, and concrete containing tiny glass beads. "These microspheres are very light, and they make a very strong concrete. That was one of our innovations," says Washington.

Leaving the wounded canoe back at MIT, Washington and Mike Chen traveled to the regional competition at Univ. of Maine at Orono to assess the competition on the non-racing elements. "I think we would have done fine with the presentation. The Univ. of Rhode Island was someone to watch, though. They were very professional and I have a feeling they knew what they were doing on the water, too."